Science topic

Biosensors - Science topic

Device combination of biorecognition receptor and physicochemical transducer
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i have uploaded image about question.i want to design some biosensor in electrochemistry. i need two chemical molecules (A & B). A is conjugated on a surface by some linker and B is connected to a electrode surface. when the linker breaks, A and B should joint each other especially with targeted linkage. A should have a property to induce electric current in B.
please guide me which molecules can be A and B?
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Good afternoon, you can decorated many electroactive lable by streptavidin, e.g. nanoparticles, HRP enzymes or..., there are also many commercial electrochemical lables based on Streptavidin.
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I'm searching for a bridge for my biosensor
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Too complicated, buy it from sigma or jenkem.
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I want to determine the glucose concentration of my samples using the Biosensor. However, my samples contain glucose oxidase (GOD) in order to remove hydrogen peroxide from my samples.
The principle of the biosensor is that the glucose in the sample generates hydrogen peroxide by glucose oxidase in the enzyme electrode. Then, the generated hydrogen peroxide is oxidized by the platinum anode. The glucose concentration is then determined by the change of the currect value according to this oxidation.
Because my samples contain glucose oxidase, the glucose concentration decreases.
I determined the glucose concentration of a known sample, having a concentration of 1.9 g/L. However, when GOD is added to my sample, the concentration decreases to 1.75 g/L .
Therefore, I want to remove glucose oxidase prior to using the Biosensor. How can I do this?
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Roy Cohen Thank you very much for the reply Sir Cohen.
My mistake, I have glucose oxidase in my samples in order to produce hydroygen peroxide and in order to remove hydrogen peroxide, I added catalase since the biosensor uses hydrogen peroxide to determine the glucose concentration.
Because my samples contains both glucose oxidase and catalase, the concentration of glucose read by the biosensor deviates and decreases.
I thought of heating my samples to denature the enzymes present in my samples. However, my samples might evaporate. So I am still not sure how to go about this. Thank you very much your suggestions, Sir Cohen. I will keep this is mind.
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I am having some issues with Bovine serum I have purchased and am wondering if there is a better serum to purchase that others have had better success using? any advice would be appreciated.
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Dear Victoria
If your biosensor is going to be used for human diagnostics, I would strongly recommend using normal human serum. Merck-Sigma Aldrich does sell this product.
One other point. If your biosensor is intended for use on whole blood, you may need to test in normal plasma as well to find out any interaction with large plasma proteins such as fibrinogen.
Good luck.
Siva
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I want to calculate the LOD for this sensor, based on the figures in this table.
I know that LOD is 3 x std LOB
But what is a method to decipher LOD from this data set?
Thanks
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Hi Tom,
Apart from the data of the low concentrations, blank injections are also needed to calculate to S/N and LOD of an established analytical method.
As I am working in environmental chemistry, common we prefer to use method detection limit (MDL) to describe these things, and you can visit "https://www.epa.gov/cwa-methods/method-detection-limit-frequent-questions" for more information.
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I'm using COMSOL Multiphysics SW for the design of biosensor.
I want to add peizoresistive material for the sensing purpose. But there is no peizoresistive Material in materials library. So, I hope I can add it from outside. But I don't know how add.
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Dear Yonas,
Just Right-click on the Materials Section. In that, you can click Blank material. Add the required properties under the material setting using a right click. By clicking the particular properties in the material section you can add the values.
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Currently I am working on SPR-PCF biosensor for biochemical detection , i am stuck in comsol multiphysics to find the sensitivity of SPR-PCF sensor how to do the analysis where to put the formula and how to check the results in comsol please someone suggest me the solution and please give the detailed explaination for that
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I also want to know. What's the expression of relative sensitivity for comsol
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Hello everyone,
I had written two papers. One of the paper is on analog performance of GAA MOSFET and second one is on bio sensing performance of GAA MOSFET.
Both these papers are simulation based. I had sent them to various journals but unfortunately got rejected due to absence of any device physics( I am working on device physics in my current work-next paper).
I want to know if any Scopus or SCI based journal that can possibly accept these papers. I am really depressed since its been more than a year but its getting rejected. Any Scopus journal will also work but should be recognized.
Please, suggest me some journals seniors and respected people. Kindly help me.
DOMAIN- Electronics(VLSI) and MOSFET based Biosensors
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It is important to consider the peers comments. Most of the journals do not accept only an empirical analysis from simulations results. Surely, including an analysis from the device physics would increase a lot the probability your paper be accepted
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In an ionic solution a charged surface also attracts counterions from the solution, forming an electrical double layer (EDL). This EDL effectively screens off the charge, and in physiologically relevant conditions, the characteristic charge screening length (Debye length) is less than a nanometer (nm). Thus, in high ionic strength solutions, charge based (DC) detection is fundamentally impeded. What are established solutions to overcome this problem?
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Yes - don't use DC detection. I assume your target is also charged. Try using EIS, with double-layer capacity as the variable of interest, since it will be ultra-sensitive to the concentration of charged species.
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A pH-responsive hydrogel was synthesized and dried. It swells at higher pH and shrinks at lower pH. How can this behavour be utilized in making a biosensing device?
Moreover, if superparamagnetic iron oxide nanoparticles are embedded in the pH-sensitive hydrogel, how can this material be used in making a biosensor?
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Dear Anurag Priyadarshi, please have a look at the following attached free review papers. My Regards
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Hi everyone,
I am working on a lateral flow rapid test using the sandwich method. I tried different parameters to get the result in the full test but no success. However, it works in the half test format.
When there is no sample and conjugate pad and I put the antigen and conjugate AuNPs in a well and run the half strip, it works and when I run the full strip it did not even show a faint line.
Any idea about what to do to solve the problem.
P.S. I want to use the strip for detecting the antigen in 100 ng/mL concentration.
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It look that most of the conjugate is stuck on the pad and doesn't continue to the membrane. Try to separate the Sample application pad & conjugate pad (use glass fiber for conjugate), sorther sample pad also better, try add serfactant like triton or tween to the conjugate.
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Many biosensor schemes have been developed as an alternative to classical methods, please explain?
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Screen-printed wearable/ portable sensors for health monitoring/ disease diagnosis/ environmental hazard analysis/ drug testing.
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The unique physicochemical properties of CNTs make them among prime candidates for numerous applications in biomedical fields including drug delivery, gene therapy, biosensors, and tissue engineering applications.
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Limitations of carbon dot or carbon dot based products for commercialization.
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We have tried to address a few things in this direction in our latest review article.
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We have designed a dual enzyme electrochemical biosensor that generates glucose at the end and ultimately to H2O2 to generate the signal with help of glucose oxidase. We would like to challenge the proposed biosensor in serum samples however, glucose that is already presented in those samples in high concentrations I suppose can interfere with the signal. Can someone suggest how to avoid the interference?
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Hi, maybe you should check the amount of glucose in serum by a YSI analyzer first.
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I am currently determining EIS spectra on different carbon-based electrodes. For this, I use a PalmsensPS4 at pretty standard conditions in a three electrode setup (0.1 Hz to 100 kHz) and measure against OCP in a 5mM [Fe(CN6)]3- / [Fe(CN6)]4- (1:1) in phosphate buffered saline (PBS) at pH 7. I then use EIS Spectrum analyser to fit the curves. One type of my electrodes results in data that can be easily fitted with a standard electrochemical Randles cell (yellow in figure). The other type, however, seems to have lower impedance overall, and very low charge-transfer resistance in particular, and I cannot seem to find a model that fits it (blue in figure). When I modify the electrodes with PEDOT, I get the same picture.
I have some questions relating to this:
(1) How can I explain, in EIS terms, what happened to these electrodes?
(2) Which model can I use to generate useful fits?
(3) Are there any papers in which these strange EIS curves have been obtained and are explained?
(4) Is it worth to change experimental conditions and what would you change to obtain meaningful data? I was planning to change the electrolyte concentration and / or the potential (though I am not sure if that would give any meaningful results).
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Don't mention it. We're happy to help. Like the medievals said, "respondeo dicendum":
(1) You can see your Bode plot (the -Phase one) with some peaks in this plot. I've attached here your plot with the max points I've told you earlier. So, in both experiments you have three maximum points in phase angle: in high frequencies (circa 105 Hz, which is the double layer phenomena in the electrode/surface region), another one in middle frequencies (circa 103 Hz, which is the charge transfer reaction), and another one in lower frequencies (between 100 Hz and 10-1 Hz, which is the electrochemical diffusional region). Since then, you have some interesting things here: now you can undersand better which goes on your electrode's surface, since there you have two behaviors: at high frequency the blue plot shows a very tiny semicapacitive circle (as seen in Nyquist's plot) but vanishes in the yellowed plot; the middle frequencies increased the phase angle (which means a decrease of resistive behavior of your electrode's surface), and finally in lower frequencies the diffusion changes between blue and yellow. So, maybe your modification improved the performance of ferri/ferro electrochemical reaction. Being a SPE electrode, the mass transfers changes a lot. For instance, the diffusion changes for a "semi-infinite" to a finite diffusion due to the diminshing surface area of your electrode. So, the classical Randles diffusional electrochemical circuit won't apply in your case and everything in your system looks fine.
(2) Yes, that's OK. The KK test isn't so easy to understand but their results are. See, your test showed a residual error less than 3% in all frequency range, and your KK data shows which I assumed in my answer: your system looks good.
(3) Yeah, impedance is beautiful but the current literature lacks on those experimental things. But I really like to discuss those electrochemical things in my research papers, and maybe sometime I'll publish some literature regarding this.
Hope it helps, and fell free to discuss anytime. 🤓
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I am trying to get an accurate measurement of the size of a commercial carboxyl coated QD, vendor states the size is between 15-20nm. The sample is in a Borate Buffer at pH9.0, the same buffer the QDs were packaged. The scan has an intensity distribution: 70+/-111.1nm; volume distribution: 2.6+/-2.1nm; number distribution: 1.5+/-0.5nm. I am wondering why the volume and number distribution are reading low and not closer to the 15-20nm range as the vendor states.
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Quantum dots can be tricky in DLS: if there is fluorescence interfering with the scattered light, then this can lead to a reduced intercept. In that case, a narrow band filter can help overcome that, or reduce the effects from that fluorescence (incoherent) light. Here is some additional info on that: https://www.materials-talks.com/2016/03/03/what-is-a-narrow-band-filter/
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Hi!
I am having some DNA probe conjugated on gel surface (polyacrylamide) and I want to perform reverse transcription and PCR after the DNA probe capture target RNA. Yet the volume of water absorbed in the gel cause a problem. How should I calculate and decide the amount of reaction mix to use? should I directly add same volume, 2X concentration onto the gel (20ul gel in a well)?
Thanks!
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Hi!
It is commonly used of silica membrae membrane in DNA extraction column to bind and release DNA. Yet I wonder can I simply use extraction tube to filter and collect ~20um beads (conjugated with DNA), then take out the whole membrane for the downstream reverse transcription, exonuclease and PCR. Will the membrane block or impede the enzyme to access the DNA on spheres? The membrane will be fully immersed in the reaction mix.
Thanks!
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organic field effect transistors OFETs for biosensors, chemical and optical sensors.
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Dear Panagiotis,
many thanks for sharing this very interestig technical question with the RG community. In this context please have a look at the following potentially useful article which might help you in your analysis:
Towards Flexible All-Carbon Electronics: Flexible Organic Field-Effect Transistors and Inverter Circuits Using Solution-Processed All-Graphene Source/Drain/Gate Electrodes
Luckily this paper is freely accessible as public full text right here on RG. Also please see the following Open Access article:
Picene and PTCDI based solution processable ambipolar OFETs
(see attached pdf file)
Good luck with your research!
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Is it necessary to do SAM before Fibronectin? With this modification, how long does it take for cells to spread on top of an electrode?
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Hi Tien,
It depends whether you want to fix the cells, to immobilize the cells, or capture the cells with their specific antibodies.
So, kindly elaborate more information to give you the appropriate advice/answer.
Good luck,
Rabeay
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I have made a fluorescent protein biosensor that is sensitive to temperature. I will need to measure the signal at 30 degrees by flow cytometer. But normally, samples were run at room Tem. And the sheath fluid is also at room Tem. How can I measure the biosensor by flow cytometer at tem higher than room tem? Someone told me that the time from sample to the detectors is within mili seconds so it should be fine but I am not sure about that. Anyone has any suggestion?
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Sorry, these questions are not my specialty
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Recently, I am working on a new project for developing the glucose biosensor based on electrochemical measurement. I don't have too much experience in electrochemical analysis and electrochemical biosensors, so I would like to ask some questions and I hope some experienced researcher can help me out.
1. I read several papers related to the glucose biosensor and in the papers, most of them were using the Prussian Blue as the mediator for transferring the electron from the enzyme (glucose oxidase) to the electrode. However, the synthesis of the Prussian Blue required dissolving the K3[Fe(CN)6] in the hydrogen chloride solution ( which is a strongly acidic solution). And I am worried about is there any risk of mixing the K3[Fe(CN)6] with HCl? For example, is there any possibility that there will be the release of HCN?
2. I want to use chronoamperometry for the measurement but I don't know how to select the appropriate potential for the measurement? I think I will do the measurement with the selected potential and based on the current change, I can determine the glucose concentration. So should I do the CV firstly and then which potential should I choose? Potential of peak current in the CV or others?
Thank you so much for the reading. And please give me some ideas. Thank you in advance.
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1 Don't worry about the addition
2 You can use the CVs to determine the oxidation potentians for you substance first. Then use the DPV or SWV to get the oxidation peak current values. CVs is the most reliable techniqe for potentials analysis and the SWV or DPV has lower background currents, which are more accurate in peak currents than CVs. You can read the book below. Also a latest work finished by our team took the strategy above, just for reference.
ELECTROCHEMICAL METHODS
Fundamentals and Applications. Allen J. Bard
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Respected all, can u please suggest me blocking buffers for DNA based biosensors other than BSA and mercaptohexanol ?
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You can try hexylamine or ethanolamine as an effective alternative of BSA.
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QuestionAsked August 11, 2015can we calculate from slope of the linear concenterationI calculate sensitivity and limit of detection for biosensor?
Relation ship between sensitivity with electrode area and slope of the probe
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Dear Dr. Adane Kassa ,
I suggest you to have a look at the following, interesting paper:
- Highly Sensitive Biosensors Based on Biomolecules and Functional Nanomaterials Depending on the Types of Nanomaterials: A Perspective Review
Jinho Yoon, Minkyu Shin, Taek Lee and Jeong-Woo Choi
Materials, 13(2), 299 (2020); https://doi.org/10.3390/ma13020299
My best regards, Pierluigi Traverso.
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I was checking Ag-Ab interaction using biosensor (APS)and then I got a association dissociation curve that increasing at both steps and so I need to explain that if there is available reason.
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My first thought here is a buffer mismatch. Have samples been dialyzed to the same buffer, and is the buffer consistent between wells used for different steps?
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I fabricate some gel bead as a kind of biosensor with DNA probe conjugated. However I found there was some kind of dust induced during fabrication. Can I use a stainless still mesh to filter (The reason not the plastic ones is that in my experience it has high affinity to DNA)? If the affinity is high then alternatively how can I isolate my bead with the dust (in centrifuge both appear in sediment)?
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Okay. So the particles are quite large. It is not true that all polymer/plastic filters have high affinity to DNA. It depends on the charge and surface modifications. If I were you, I would talk to the technical advice department of filter manufacturers (eg, Nucleopore). Good luck.
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When designing an experimental setup and we want to buy a certain chemical, for example; let's say we want to buy penicillin; cas number: 61-33-6.
Then we realize that we don't have enough money for the experiment with this chemical. But related chemicals such as
113-98-4 (mono-potassium salt)
69-57-8 (mono-hydrochloride salt)
are cheaper and we decide to purchase one of these two products. But of course their cas numbers are different.
How logical and reliable would it be to continue the experiments in this way and try to make a publication?
Let's say I asked this situation to write an article in the field of biosensors.
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Arrogant posts are never helpful.
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I want to know that how biology can be related (in any way) for the study of MOSFET biosensors or FET based biosensors. Any suggestion will be highly appreciated.
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Thank you Riaz A. Khan and Niazul Islam Khan sir for the response.
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Many biosensors can be used to sense the infectious material, what is the extent of the usage of the optical biosensors specifically
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This seems to be quite difficult. Do you have a specific approach in mind?
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Hi,
I am working on biosensor with mvenous and mcherry. I fix the cells at different time points image them and then bleach it to remove the signals of sensor and then stain with Edu and DAPI. Now I have to use cell profiler to analyze them. Can someone guide me how to use the cell profiler to analyze it?
Thank You
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@Petra thank you for the link. I will look into it as well.
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I've followed many articles to find out the relationship of various concentrations and the potential of GSH or GSSG in different cellular organelles but it's quite confusing for me to find out how do we convert these to different entities to each other?
Can someone please explain the Nernst equation to find out the potential of different cellular compartments?
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I think this article will be helpful for you.....Please go through this link below...
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Because I need to find out some nano biosensors to study.
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Hello,
I'm interested in research in fiberoptic biosensors, MEMS AFM microscopy, photonic biosensors.
If it is no problem could you suggest the cutting-edge area research fiberoptic biosensors, MEMS AFM microscopy, photonic biosensors for a research proposal?
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'sorry' for what?
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Currently, I am trying to simulate a surface plasmon resonance (SPR) biosensor on a multilayer structure using FDTD Lumerical software. I am a beginner and have never used this software before. Are there any tutorials related to SPR simulation using this software? This document was very meaningful in completing my research.
Thank you
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Hi Devi,
Lumerical software has a bunch of "example" simulation you can try from their fresh installed. The simplest way to start, you call one of this sample, take a look at the simulation design and condition, and how it works then try to modify and to your own case, you can change the material, or change the shape, or size (step by step). Do not forget to "save as.." to the new file name in your common folder.
Then try to run, and you got your first simulation case on Lumerical. If the error appears, you need to trace back from the example file, what was the mistake, then try to fix the error.
Good luck.
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In a typical paper around microalgae biosensor, an increase in current was illustrated with time by chronoamperometry. But, my observations showed a decrease in current with time and I wonder what problem may occur?
Could it be cause of electrochemical method or the kind of microalgae species?
Please share me your experiment and knowledge.
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Dear Dr. Berthuel
Thank you for your reply. In fact, I used the stirrer in my test but the the trend of signals did not change. I use an autolab for receiving chronoamperometry scan, the working electrode is glassy carbon with Ag/AgCl ref.electrode and I use BSA-Glutaraldehyde matrix for immobilizing microalgae cells. Here is a paper with similar work, it indicates an increasing slope in chronoamperometry and I gained exactly reverse.
I would be grateful if you could help me for solving this problem.
This is the mentioned article: Chlorella sp. based biosensor for selective determination of mercury in presence of silver ions
doi: 10.1016/j.snb.2012.02.009
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can we calculate from slope of the linear concenteration
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The sensitivity S of a detector is its response y divided by its excitation x.
That is S=y/x,
If the device is nonlinear then one can define the differential sensitivity as Sdiff= dy/dx. There is also a normalized sensitivity Snor= (dy/y)/ (dx/x )
As for the minimum detectable excitation xmin is called the detectivity D of the detector and it is set by the noise in the detector. If the signal is immersed in the noise it could not be directly detected.
Best wishes
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I am working on a project in which I need to do the molecular dynamics simulation of electrochemical DNA-based Biosensors using LAMMPS. Can anyone help me?
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Dear Misha Urazaliev, Thank you for your guidance
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I am thinking of isolating the protein from soil or leaves sample with the pesticide.
But I am quite lost with the minimal medium I would use, Do anyone has a paper or an advice on the best way to go about this?
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Hello dear Maryam
You must first see what limit detection you need then you can design the fabrication based on different methods, each method has its own advantages and disadvantages
Carbon-based methods are good methods for detection
Please review this resource
Successful and victorious
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The antibodies to the protein of interest should be attached to the biosensor and thereafter this biosensor should evaluate the amounts of this protein in the organism's liquids.
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Dear Dr Sayed Mojtaba,
Thank you so much for your support.
Regards.
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I would like to fabricate a nanosensor for sensing application of biological molecules like cholestrol, uric acid etc
Please discuss how can I select a suitable polymer and the nanofiller (two dimensional material, MXene etc) to develop a new composite sensor material which would give good results using electrochemical workstation of three electrode system
Expecting valuable suggestions
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Hi!
I am trying to pack one bead per drop using microfluid. I previously assumed that just adjust bead concentration in accordance to how many drop per minute. Yet this route failed. I think I need to read more on packing cell or bead in microfluid, yet I didnot find many materials. Could you recommend any paper/protocol/note/piece?
Thank you!
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Thank you! Ali Kalantarifard That's what I am looking for
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Dear friends
I am studying on the biosensor about SARS-CoV-2 infection. I investigate the main Protease (Mpro). could you please inform me "what is the proteolytic product of "Mpro" at the end of the reaction? for example pH changes via proton (H+) releasing or other factor?
Thanks in advance
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Great discussion
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I realized many papers use scan rate 50mV/s or 100mV/s. But how do actually they determine the right scan rate to use throughout the experiment? What are the measurements that I should take into account in choosing it?
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Choosing the scan rate in cyclic voltammetry depends on what purpose you want it to serve. Imagine you want to study two consecutive oxidation processes using cyclic voltammetry. You get one peak at, say, +0.6 V, and the product of this reaction is then further oxidized at +1.2 V. Now, if you choose a little too slow scan rate, you might miss the second oxidation peak as the product of the first oxidation (+0.6 V) may simply diffuse away. By contrast, scan rates too fast might distort the course of your cyclic voltammograms, and they are usually useful in, e.g., liquid flow techniques, where you need to record the entire cyclic voltammogram almost instantaneously since the composition of the solution changes in time.
Scan rates between 50 and 100 mV/s are usually used to "probe" the given compound's electrochemical behavior, and then you can vary it depending on the information you aim to obtain. Moreover, for analytical purposes (biosensors), other voltammetric techniques, such as differential pulse voltammetry, may be appropriate.
Jan
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I am trying to make a DNA sensor but I am detecting non specific binding. Does anyone know a better blocking agent for DNA sensors based on rGO, apart from BSA or MCH?
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No, PEG6 blocks the free linker molecules like PANSE. Any short carbon-chain ended with -S will block gold surface. I don't have a suitable one for rGO.
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Dear colleagues
I have troubles to read out the correct anodic peak currents from my cyclic voltammogram since ORR is pushing down my baseline. Is there anything (besides substracting a proper blank) that i can do (mathematically?!) to get correct peak currents? Nicholsons empiric equation only applies to reverse scans, as far as i understood, and doesn't help me...
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And How about subtracting a background curve w\o the analyte but with the residual oxygen present ?
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Despite the fact of the tremendous number of research papers in the literature dealing with the usage of aptamers as molecular probes in biosensing, and despite the fact that this technology is almost 30 years old, there is only just few companies producing aptasensors and aptaessays and the majority of them are startups, and almost no commercial biosensor or kits is currently available in the market.
Can anyone explain to me why there is such gap?
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Definitely stability issues. DNASe and RNAse are very efficient and ubiquitous especially in biological matrices. People have tried to modify the aptamers to overcome this issue with negative outcomes of sensitivity and specificity.
Also people are developing AptaMIPs but shield the apatamer but steric hindrance to ligand binding is a major issue.
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Greetings,
I have a short stretch of 20 aa with strong binding affinity for a compound. I am trying to de some whole cell flourescence or visible biosensing technique based on this peptide. Can someone suggest a reliable genetic trick for the protein biosensors?
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Ignacio Moya Ramírez how will i sense its capture thats the issue? compound can pass bilayer we can do characterization in cytoplasm itself. issue is to sense its binding with my peptide.
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What media or salt solution (HBSS, EBSS, Tyrode) can be used for real-time intracelular h2o2 imaging? I am using a genetically-encoded biosensor based on roGFP and have to find the media that wouldn't have much buffering capacity as well as compounds acting like antioxidants, since it is important to see how the cells alone are coping with h2o2 adition.
Estimated duration of the experiment - 1-1.5 h.
Cells: ipsc-derived neurons. Standart Neurobasal+B27 media was designed to protect neurons from any kind of oxidative damage and contains loads of antioxidants, so h2o2 don't get the chance to get inside the cell.
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The Cell Meter™ Hydrogen Peroxide Assay Kit OxiVision™ Green hydrogen peroxide sensor to quantify hydrogen peroxide in live cells
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Hi to all I immobilized a peroxidase on a new synthesized MOF. The reviewer of a journal paper asked me to consider the inhibitory activity and specific affinity of my immobilized enzyme in the introduction. How I can answer this comment of the reviewer for a journal paper revision? What does it mean? In my opinion, these items are related to biosensors. I reported the influence of immobilization on km in my article but I have no idea about the inhibitory activity.
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The specific activity of an enzyme preparation is the turnover-number (molecules of substrate that an enzyme molecule handles per second) multiplied with the enzyme concentration.
What your reviewer is in effect asking is
  • whether the enzyme might have been partially damaged during immobilisation
  • whether there is any steric hindrance to substrate binding/product release due to the immobilisation.
Any such effect could invalidate your observed Km. However, I am not sure that this belongs into the introduction. Evidence of full activity should be presented under results, and its significance in the context of the paper discussed in the discussion section. An exception would be IMHO if the immobilisation procedure is well established and proven to result in fully active enzyme, than this would be mentioned in the background part of the introduction, with appropriate references. Of course, you'd still have to very that your preparation is fully active, and this should be mentioned under results.
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In research publications, it is often said that electrochemical sensors and biosensors are simple, portable, and easy-to-use. However, optical sensors (mainly colorimetry and fluorescence) are widely used in real clinical analysis, not electrochemical (except glucose sensor). ELISA, PCR, or whatever the biosensors, colorimetry, or fluorescence read-out are preferable, while electrochemical biosensors are seldom preferred by clinicians, why?
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The problem associated with EC sensors is not their feeble selectivity because EC sensors have also enough selectivity and specificity. Even, the EC sensors are more sensitive. In my opinion, less availability of EC sensors in device format may be the concerned issue of least usability by clinicians. I think, the future of mediator-free EC sensors based devices will be more brighter.
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Electrochemical microrna biosensor
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Dear Researcher,
There is no difference in both ends to modify if the modification does not lead to interference in its hybridization. you can also study the attached article below:
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I was wondering if there is any commercial LSPR biosensor based on gold nanoparticles aggregation for clinical usage, especially as a point of care testing (POCT).
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As fas as I know, LamdaGen sells LSPR Biosensors:
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how to estimate the response time of the electrochemical impedance spectroscopy biosensor
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In my opinion, EIS is not measuring a transient (i.e., time depending) signal.
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I'm currently trying to develop a biosensor to detect covid19 infection. However, I don't want to be exposed to the real virus for a real practical test. Is there any way, to simulate viruses so that a researcher can use these simulators without worrying so much about being infected?
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Hi Hadi
Looking at your question, I only think of Virus-Like-Particles (VLPs) which are non-infectious. Look at this article which might be of your interest
Best,
Kiran
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I was wondering how to calculate the copy number for a viral protein from the protein concentration? I.e. for 1 mg covid protein (N or S protein) what would be the copy number? Thanks in anticipation.
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Thank you
Ozodbek S. Abduraimov
and Adrian Filiberti for the answers, it was helpful. Appreciated!
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For a range of concentrations of protein, I am getting the I-V (Current-voltage) data from a Keithley sourcemeter. Accordingly, I am getting the resistance as the response of protein-protein binding on carbon nanotube on my biosensor. What formula should I use to get normalized response versus concentration gradient? Is there any good textbook on this to show the calculations step by step from scratch? Thanks in advance.
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Dear Touhid,
Prof. Reg Penner's work in Nano Lett. with virus bioresistors for HSA protein detection may be of interest to you. Figure 5 shows the change in resistance as a function of protein concentration (calibration curve). The mathematical fits to the Hill equation are outlined in detail, with more information provided in the Supporting Information. EIS data is also provided to establish an equivalent circuit. This paper may represent a good model for comparison as you put your work together!
Kind Regards,
Matt Glasscott
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I am trying to design a boron nitride based biosensor that can sense the abnormality of microbial activities on fish skin. I am very curious that is it possible to have such an aptamer that can detect the behavior of microbes? Instead of knowing what they are, I care about what they do.
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Interesting question with great insights. Looking forward to the discussion!
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Can we do semi quantitative detection in lateral flow ?
Say for example if we have X concentration of antigen present in body and we want to detect above the X concentration of it in lateral flow , can we do that ??
I have come across a lateral flow device of SD biosensor in which they say if there is more than 20 ng/ml concentration of CRP in body it will produce colour.
Do anyone has idea how we can do that ?
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The barcode/ladder-bar lateral flow assay format may suit you needs. It involves printing multiple test lines on the same LFA strip with varying concentrations of antibody so that each test line will have a different "cut-off value" which is the concentration of the target analyte required for that line to become visible by the naked-eye. While useful this method is practically limited to 3-5 different concentration ranges due to limited resolution and room for printing on the membrane so it won't work for all applications. I have used this method for the development of an LFA for semi-quantitative detection of beta-trace protein for detecting CSF leaks which you can find on my profile. It's also been used for quantification of C-reactive protein in blood and gliadins in food samples. Other than this, the best approach would be using an electronic bench top or cell phone reader to compare the assay signal to an internal standard curve.
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Dear all
My research is on biosensors. Now I have to use gold nanoparticles and PAMAM dendrimers to modify the electrode.
I am struggling to understand the interaction between the two maybe it's because of the structure of the dendrimers.
Can you kindly assist, clarify the chemistry between these two please.
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Do you have any capping agents on the AuNP? If you have capping agents on the surface of the AuNPs such as carboxylate functional group, it can form ionic interaction with the amine groups on the PAMAM dendrimers.
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Hi,
I am looking for substantial evidence of effect of geomerty of flow channels (microfluidics) on the sensitivity and feasibility of Surface Plasmon Resonance (SPR) Biosensors with respect to different applications (whole cell, protein or DNA detection). I know one from Prof. Jiri Homola.
I need to design my own microfluidic channels for SPR sensing applications. Please guide me.
Thanks :)
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I'm developing an impedimetric biosensor for lipase.
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Dear Karine.
There is no consensus in the detection limit determination in biosensors or other analytical measurements. but I'm currently using "3 sigma" method:
Slod= Sblank + 3σblank
where "σblank" is standar deviation of 10 blank curves, "Sblank" is signal of blank curves. You can also calculate LoD by the equation below
LoD= 3*σblank/ (slope of linear part of calibration curves).
Best Regards
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I want to know the most important Characterization for imprinted polymer molecular print in biosensor for formaldehyde detection. 
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Dear all, please see the following document. My Regards
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Biosensors are successfully used for the quantitative estimation of several biologically important substances
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Biosensor is defined as a device that uses specific biochemical reactions mediated by isolated enzymes, immunosystems, tissues, organelles or whole cells to detect chemical compounds usually by electrical, thermal or optical signals.
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Any one had developed product like Blood Glucometer for detection of COVID-19 infection
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Dear all, I was thinking on similar strategy to develop sensors for viruses. My idea is based simply on developping sensors bearing the constitution of the elements targets for the virus, which in the case of covid-19 is the ACE-2. But no practical work is done right now. My Regards
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There are a large number of sensor technologies available to detect a particular type of analytes.
I understand every platform has some limitation and some advantages among others.
In current situation which type of biosensors (FET/elctro-chemical/luminescent-based/electro-luminescence) provide more reliability to become a part of future point-of-care?
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Third generation of Biosensors (Amperometric enzyme electrodes) should be the choice of future because of no interferences and their attractive performance.
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Could you please link me with an article related to the CNT based bio sensors?I am not expert enough due to my background to find out.
I have following materials :
1. Glutaraldehyde 25%
2. 3-amino propyl (terimethoxysilane )97 %
3. Glocuse oxidase
4.Any kind of agent acids
Please kindly help me to find out the concentrations and steps by linking me to a related article or any kind of reports,
Personal Regards
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There are too many publications that have immobilized GOx onto the CNT electrodes using drop casting or immersion methods, many of them claim to obtain DET to the electrode surface. However, this claim was finally beaten in 2018 by Philip Bartlett and I. If you are interested, have a look at the following paper: https://www.sciencedirect.com/science/article/abs/pii/S1572665717304496
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I would like to immobilize boronic acid (3-APBA) solution on Grade 4 Chr Cellulose Chromatography paper. Which technique I should do?
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Boronic acid might be immobilized onto cellulose paper via cross-linking which is an irreversible method done by the creation of intermolecular cross- linkages between the molecules of the enzyme by covalent bonds.
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Dear All,
I am working on research related to fabrication of glucose biosensor by using screen printed carbon electrodes (SPCE). I modified the working electrode with nanocomposite and then immobilised glucose oxidase-glutaraldehyde mixture on the modified SPCE.
Here are the detailed steps:
1. Preparation of nanocomposite.
2. Mix 20 μL of the 2% glutaraldehyde solution with 50 μL of Glucose oxidase. The mixture was allowed to sit for 30 minutes at room temperature before use.
3. Drop cast 3 μL of the nanocomposite onto the working electrode (WE) of SPCE.
Immobilization of Glucose oxidase-glutaraldehyde mixture:
1. Drop cast 3 μL of glucose oxidase-glutaraldehyde mixture on the modified SPCE
2. Allow the solution to adsorb onto the modified SPCE for 24 hours at room temperature.
3. After 24 hours, wash the unbound glucose oxidase from the working electrode using 0.01M PBS (pH 7).
4. Let the SPCE to dry at room temperature.
The MSDS mentioned that optimum storage temperature of glucose oxidase is -20°C.
As I am performing the immobilization of Glucose oxidase-glutaraldehyde mixture at room temperature for 24 hours, will it affect the stability of the glucose oxidase?
Plus, should I be storing the SPCE with immobilised glucose oxidase at room temperature or at cool temperature (probably 4°C)?
Help appreciated!! Thanks
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-20ºC is the recommended temperature when the GOx enzyme is under a solid and dry form especially when you are considering long term storage (see paper attached).
Performing the immobilization of GOx at room temperature for 24 hours could affect its activity but, as Siba Moussa mentioned, glutaraldehyde could help its stabilisation.
Working with GOx and biosensors, I recommend a storage (immobilisation process) at 4ºC especially because the GOx is dropcast within a solution.
I hope this helps.
Best regards,
Marie B.
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I'm interested in very small changes of human skin temperature and so far I didn't found anything better than 0.1°C. I know there are a lot of sensors with a higher resolution but this unfortunatelly doesn't tell me anything about repeatability and precision. In a nutshell, I am searching for a sensor with high accuracy, high precision and high repeatability and would be glad to get some hints from the community.
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In order to a fast and accurate measure skin temperature for fever detection (covid-19 for example) it will be necessary infrared thermometers (including thermal image cameras) calibrated (with metrological traceability to SI) with uncertainties of the order of 0.1 ºC, within the range of 35 ºC and 40 ºC. Special calibration procedures, including in situ calibration and facilities for its realisation, for example in airports, will be essential.
Calibration Laboratories (accredited under 17025) and NMI, have to be ready to answer the near future demand for this special type of measurements. None skin temperature measurement (for fever detection) would have to be considered reliable without a calibration certificate assuring the metrological traceability of the thermometer.
The calibration have to inform to the user, on the corrections to apply and the assiciated uncertainty.
Measurements obtained with non-calibrated radiation thermometers, can lead to wrong deccisions in respect to prohibit or not, the passage of people to a certain area, city, country, etc.
In my oppinion it will be of crucial importance hereinafter.
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I am trying to understand the use of interdigitated electrodes for use in biosensors and wondering: how to choose a configuration(geometric parameters) to start? Can I simply get a random one and try to optimize?
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I wouldn't start with too small and too close electrodes (such as those with 5 - 10 um in width and gap), because in general they are the most sensitive, but also the most difficult to manage. Many of the paper I read uses the 100 um (width/gap) interdigitates, these devices can be a starting point, then to be optimized according to what use you make of them.
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When testing a biosensor with different concentrations of antigen, it is said that the electrode should be flushed with PBS. Is PBS alone sufficient or the washing protocol with PBS+Tween 20 and PBS should be completed each time?
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Doesn't Tween-20 will wash out the antibodies from electrode completely?
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I'm preparing a biosensor from p- type silicon , i think etching is easier , it does not need illumination , but i need to know in scientific manner , it using p- type more affordable ? because i see that most of previous work the have chosen p- type also
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Dear colleague the porous silicon type n is defficile to obtained this refers to it is needed to illumination exceptionally in in nano porous silicon, for this all researchs we find the type p
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I need nitrocellulose membrane for lateral flow assay for antigen detection. Having searched for other companies, they are only specialized for western blotting. So can the same nitrocellulose membrane be used for LFA also?
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If you talk to anyone in the lateral flow industry from the major contract assay development and consulting firms based in the San Diego / Carlsbad area, they'll tell you that there are really only 3 membrane suppliers they trust when it comes to making high quality membranes for LFAs.
  • GE Healthcare (Whatman)
  • Millipore
  • Sartorius
PALL Corporation makes LFA membranes but they have a limited selection and only offer Vivid 90 LFNC and Vivid 120 LFNC membranes. There are some other companies such as mdi Membrane Technologies (based in India), and various suppliers in China, Korea, and even Japan. However, the majority of FDA-cleared and CE-marked LFAs are likely using GE Healthcare, Millipore, or Sartorius membranes.
There are significant differences between these three membrane suppliers. Nitrocellulose is inherently hydrophobic and the manufacturers incorporate surfactants into the membranes during manufacturing to improve wetting. Millipore uses an anionic surfactant (likely SDBS or SDS), while GE and Sartorius use nonionic surfactants (I haven't yet deduced the exact identity, and the companies won't disclose it).
For some analytes and sample matrices the membrane supplier can have a dramatic impact on LFA performance, even for the exact same wicking speed. In grad school we had a wide selection of GE and Millipore membranes, and we all pretty much assumed (incorrectly) that GE and Millipore membranes were roughly equivalent. This came back to bite us hard in one particular assay where we eventually discovered that swapping a GE membrane for a Millipore membrane (with the same wicking speed) caused an enormous improvement in signal and transport of the conjugate in a tricky sample matrix. It was like a night-and-day difference.
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I'm currently studying the detection of uric acid using square wave analysis.
In several articles that I read, the uric acid (UA) was diluted using deionized water. However, from my experiment, it is impossoble to dilute the UA using DW only. I was also advised to use 0.2M NaOH, but the problem still cannot be solved.
Please assist. Thank you.
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Hi, yeah it really works. but i need some organic solvent.
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If is it necessary to detect many different analytes which is the best technology to developing a biosensor?
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Simone, in practical terms you are usually restricted in your choice of instruments. for example, I am a big fan of SPR intruments but the high-end versions come at a cost of some 300 k€! Please provide more infos and specifications as Michael suggested.