Biosensors - Science topic

Yes, there are many companies and research institutions working on drones for biosensor application in smart agriculture. Here are a few examples:

These are just a few examples of the many companies and research institutions that are working on drones for biosensor application in smart agriculture. This is a rapidly growing field with the potential to revolutionize the way we grow food.

I am not familiar with Silvaco, and it is hard to provide meaningful suggestions without looking at the project and the errors reported !

However, consider not using all physics models at once, especially the tunneling. Increase the complexity of the models until it diverges. That is assuming that your mesh is good.

On the process, use a regular high-k in Silvaco (do not create your own material), then sweep its primitivity.

Usually, many COMSOL users export the global variable ewfd.neff to some processing software like MATLAB and then evaluate sensitivity.

There are many different types of applications for optical biosensors. Some of the most common applications include:

* **Biomedical diagnostics:**

* **Food safety:**

* **Environmental monitoring:**

* **Industrial process control:**

* **Other applications:**

Ask for a small sample from a big supplier. It works in ~30% cases

10-500 ng/mL (or 0.1-5 nM) Musa Ibne Mannan

Yes, you can. But it depends on the experimental setup and material you are using. Vimal Kumar Singh Yadav

"Development of a biosensor for the detection of aflatoxin M1 in milk using surface plasmon resonance" by Xu et al. (2020) - This article describes the development of a biosensor based on surface plasmon resonance for the detection of aflatoxin M1 in milk samples. The biosensor was developed using a combination of biophysical techniques such as surface plasmon resonance and bioinformatics techniques for the optimization of sensor design.

"Development of a portable aflatoxin detection system based on fluorescence polarization" by Wang et al. (2019) - This article presents a biosensor for the detection of aflatoxin based on fluorescence polarization. The biosensor was developed using a combination of biophysical techniques such as fluorescence polarization and bioinformatics techniques for the design and optimization of the detection system.

"A review of biosensors for the detection of aflatoxins" by Liao et al. (2018) - This review article summarizes the latest developments in biosensors for the detection of aflatoxins, with a focus on the combination of biophysical and bioinformatics techniques in the design and optimization of biosensors.

"DNA-based biosensors for the detection of aflatoxins: a review" by Kaushik et al. (2017) - This review article discusses the development of DNA-based biosensors for the detection of aflatoxins, highlighting the use of biophysical techniques such as electrochemical and optical methods, and the role of bioinformatics in the optimization of biosensor design.

"A label-free biosensor for aflatoxin B1 detection based on a graphene oxide-enhanced surface plasmon resonance technique" by Yang et al. (2015) - This article presents a label-free biosensor for the detection of aflatoxin B1 based on a combination of biophysical techniques such as surface plasmon resonance and the use of bioinformatics for the optimization of biosensor design.

Hi Diana

Maybe you should try CV and IT first.

If it is still no dose-dependent response, you can try to change the concentration range or voltage range or environment condition like pH.

I hope this helpful to you.

Regards,

Li-Fan Hsu

The assumption of H2O vapor active role is quite feasible as far as an UV-assisted ozonolysis of H2O vapor obviously could lead to some hydroxylation - https://spartanwatertreatment.com/advanced-oxidation-uv-ozone/.

Further about the possible mechanism you could refer to:

-

Hope these will help.

With conventional bulk method, you may want to bond it very well to a flat substrate then polish it with a good polisher. Please refer to www.innoviamaterials.com for more information.

Dear Smriti Mukherjee , The companion journals are (most of the time) relatively young (new) titles. Getting an index in Clarivate’s SCIE/SSCI takes a couple of years and is preceded by indexing in their ESCI. Take for example Food Chemistry (CiteScore 13.1 and IF 9.231) https://www.journals.elsevier.com/food-chemistry that has started not one but even three companion journals:

-Food Chemistry X (CiteScore 5.4 and IF 6.443) started in 2019 https://www.journals.elsevier.com/food-chemistry-x APC 2240 USD (while Food Chemistry charge for their open access a staggering 4170 USD but this is optional)

-Food Chemistry: Molecular Sciences (CiteScore 0.6 and ESCI indexed in 2022) https://www.sciencedirect.com/journal/food-chemistry-molecular-sciences

-Food Chemistry Advances (just started in 2022 so no index yet) till 30 June 2023 for free (after that APC 1750 USD)

Advantages are:

-It is like the transfer service that some publishers offer a way to speed things up. If rejected for the ‘mother’ journal all possible peer review is transferred to one of the companion journals

-The relatively young titles are less expensive (for open access)

-The companion journal profit from the reputation, infrastructure etc. of the well-established title and most likely will receive indexing relatively soon

Disadvantages are:

-It might be perceived as “your manuscript is not good enough for the ‘real’ title. Although one must acknowledge that a traditional subscription-based journal has ‘space limitations’ and simply cannot publish everything (even if good enough) despite the growth in submissions

-There is no guarantee that the new title will be successful (although I honestly don’t know examples of this)

So, yes in most cases the companion journals will receive a full indexing and compared to fully new titles this indexing happens relatively soon.

Best regards.

Yes for Bare and modified electrodes you must un OCP

Anne Sawhney's answer is dead on. Unless you're doing something very unusual the biosensor is likely to be in a fairly high ionic strength environment so most of the field will dissipate by the outer Helmholtz layer (< 1 nm). There will be a diffuse double layer but that is more related to concentration gradients, not field strength.

That said, if the distance between the current carrying electrodes is great enough, the current itself high enough, and the impedance across the gap (tortuous paths) high enough then there can be a field effect away from the electrodes themselves. This is sometimes made use of to induce migration effects (e.g. capillaries). A simple check to figure out if that is the case: if the total voltage dropped [between current carrying electrodes] is about the same as the electrochemical potential then field effects away from the electrodes are minimal. Impedance testing can complicate things but not overly so as it's a small signal. Still the high frequency components do bypass the electrode double layer but they aren't doing anything besides shifting more mobile ions back and forth a little bit out in solution.

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.

Too complicated, buy it from sigma or jenkem.

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.

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

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.

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.

You can try Silicon.

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.

Dear Anurag Priyadarshi, please have a look at the following attached free review papers. My Regards

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.

Good luck.

We have tried to address a few things in this direction in our latest review article.

Hi, maybe you should check the amount of glucose in serum by a YSI analyzer first.

Hello Sabine Kerstin Lengger

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. 🤓

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/

Check http://www.mcb.uct.ac.za/mcb/resources/pcr/concentrations

Also check https://www.intechopen.com/chapters/49705

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:

Luckily this paper is freely accessible as public full text right here on RG. Also please see the following Open Access article:

(see attached pdf file)

Good luck with your research!

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

Sorry, these questions are not my specialty

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

https://www.sciencedirect.com/science/article/pii/S0008622320307752?via%3Dihub

You can try hexylamine or ethanolamine as an effective alternative of BSA.

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

Available at: https://www.mdpi.com/1996-1944/13/2/299/htm

My best regards, Pierluigi Traverso.

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?

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.

Arrogant posts are never helpful.

Thank you Riaz A. Khan and Niazul Islam Khan sir for the response.

This seems to be quite difficult. Do you have a specific approach in mind?

@Petra thank you for the link. I will look into it as well.

I think this article will be helpful for you.....Please go through this link below...

Try this: https://link.springer.com/chapter/10.1007%2F978-3-319-58679-3_1

Also check https://www.theseus.fi/bitstream/handle/10024/158887/Nguyen_Thi%20Bao%20Ngoc.pdf?sequence=1&isAllowed=y

Dear Zhang Jiali

'sorry' for what?

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.

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

Dear Manikandan Mayilmurugan

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

Misha Urazaliev

Dear Misha Urazaliev, Thank you for your guidance

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

Dear Dr Sayed Mojtaba,

Thank you so much for your support.

Regards.

And https://link.springer.com/article/10.1007/s12668-019-00708-x

Thank you! Ali Kalantarifard That's what I am looking for

Great discussion

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

And How about subtracting a background curve w\o the analyte but with the residual oxygen present ?

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.

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.

For DNA sensors, you may want to try some smaller molecules, like , PEG6, as blocker.

The Cell Meter™ Hydrogen Peroxide Assay Kit OxiVision™ Green hydrogen peroxide sensor to quantify hydrogen peroxide in live cells

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

Any such effect could invalidate your observed K_m. 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.

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:

Dear Mehrdad Ameri ,

As fas as I know, LamdaGen sells LSPR Biosensors:

In my opinion, EIS is not measuring a transient (i.e., time depending) signal.

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

Thank you and Adrian Filiberti for the answers, it was helpful. Appreciated!

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

Veerappan Mani , I suspect because electrochemical sensors are not as robust in terms of analyte specificity for desire analytical outcomes. ELISA is very specific to an antigen and PCR simply amplifies the quantity of DNA so that it can be analyzed. Colorimetry and fluorescence are general techniques until coupled with specimen preparation techniques. Electrochemical sensors simply don't have the necessary complex separation and preparation techniques incorporated for specific analyte detection. In the future this seems like a realistic possibility, where are the analyses that highlights the gaps?

Interesting question with great insights. Looking forward to the discussion!

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.

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.

Dear all, please check the following documents. My Regards

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

Dear all, please see the following document. My Regards