Questions related to Electrochemical Biosensors
Hi. I am currenty working on electrochemical biosensors, using 2mM ferro/ferricyanide solution in Pbs and 100mM kcl. I made it carefully and done deaeration with nitrogen gas then Stored in a dark closet in a glass container. But it keeps getting decolored within weeks. I don't know if it is my mistake or it is naturall. My prevoius samples without support electrolyte (kcl) from monthes ago is still strongly colored. Thank you
I am looking for published data on the variation / strength / reach of the electric field around the working electrode for a typical 2/3 electrode electrochemical biosensor. Specifically , I am interested to model the electric field to understand the distance from the electrode where its effect / strength becomes negligible.
I want to understand how this limits the performance of biosensors, specifically those which measure impedance , capacitance etc.
I am really new to electrochemistry and I am recently trying to reproduce the cyclic voltammetry of Pt electrode that I made using sputtering. I used Ag/AgCl as reference, coil Pt as counter and my Pt electrode roughly 3x3 mm2 as the working electrode. The CV graph that I got is quit different from what we usually see on lots of literatures. see the attachment
Could someone please help with this.
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?
During the electrochemical analysis of the electrodes, I want to know the parameters of CV , DPV , EIS and how to add the concentration of analyte in the electrolyte. I am using PBS as an electrolyte and GCE as the working electrode.
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?
I am trying to run cyclic voltammetry experiments on a modified electrode. The literature shows distinct peaks for the analytes (pesticides, phenols) using glassy carbon electrode(GCE) as working electrode. I am able to get the peak signal on GCE but not on the modified electrode. What could be the possible reasons?
I'm working on electrochemical sensing drug molecule. My workstation is Origalys (origaflex 500). In papersa particular concentration is reported for every sensing studies like 200micromolar etc. How to do chronoamperometry for the sensing application and what is the relevance of this concentration. How to get this value of concentration
Please share your ideas
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).
Hello, I am doing a carbon surface modification with Gold nanoparticles.
from the FTIR below, I know the formation bond of NH3 and for COO , but I would like to know what is the range of thiol bond formation, is this FTIR good or not?
note that I know that the difference between the bare SPE and modified SPE is the increase of current which is measured by Potentiostat.
thanks in advance.
I am working with screen printed carbon electrode and FTO coated glass electrodes for sensor studies. My electrolyte is PBS solution (pH=7). Please discuss what are the initial and final frequency that are commonly used for recording EIS spectra of these electrodes (bare electrodes).
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.
I am using screen printed carbon electrode (scpe) for cyclic voltammetry in my sensing studies. The electrolyte is PBS solution (pH=7). I got the CV for bare SCPE without much noise but after coating of the nanomaterial I couldnt get any proper response instead very high noise in the CV. I tried with two different nanomaterials and tried two different coating methods (without and with binder), but the observation is same.
I am attaching the picture of noise I got.
Please discuss your valuable suggestions for solving this issue. I haven't done any pretreatment for the scpe before coating the sample
I design an electrochemical biosensor for the early diagnosis of breast cancer. I must determine the -NH2-ended aptamer to catch HER-2. I haven't decided yet, I would like to ask you. I will analyze using electrochemical methods such as CV, EIS or DPV whether the aptamer is bound to the target HER-2 or not.
When I researched articles on the electrochemical applications of nano-Au.
I found this figure and noticed an extra single cycle. And when I did my Nano Au CV analysis, I didn't get that extra single cycle. So, what is that cycle? Why does it appear on the cyclic voltammetry?
I want to keep my pencil graphite electrodes for a while in the aqueous graphene oxide solution that I have prepared at different concentrations such as 5 mg/mL, 1 mg/mL, 0.5 mg/mL, and then i would like to make graphene oxide adsorbed on the surface of PGEs and then i will reduce the graphene oxide electrochemically. After a while, the solution becomes heterogeneous as it begins to precipitate. Have you ever encountered such a situation before? It sounds good to dissolve it in a phosphate or acetate buffer solutions, in case this may related with pH, has anyone experienced it?
Did anybody encounter a situation when using a planar electrochemical biosensor to detect O2 results in a significantly weaker current (~20% lower) for whole blood compared to that of H2O? Both whole blood and water are equilibrated to the ambient, so, theoretically should provide the same I.
I am trying to measure resistance from I-V curve from a chemiresistor/ FET sensor with a keithly sourcemeter. The substrate is soaked/ wet with protein and phosphate buffer only. But the I-V line is not passing through the origin (which probably means it's not showing ohmic characteristics), rather its going through the second quadrant. What could be the possible reason. Picture is attached for reference. Thanks in advance.
my working electrode is graphite sheet and I'm using Ag/AgCl and pt electrode as reference and counter. I have problem with my solution. in some articles, they have used PBS + KCl solution and they observe the redox peaks. in some other works, they use PBS + KCl + K3[Fe(CN)]6 and they see peaks as well.
I already use PBS + KCl solution but I didn't see any peaks for redox reactions and I have a lot of noise in my CV curve.
I don't know what solution is gonna work for me.
I think the methods that have been used in
Electrochemical Biosensors like ( antibodies- aptamers-MIPs) are usually used for the short-term as we need to wash the electrode to remove the targets from it. I think it is a drawback if we want to use them in daily life wearables such as ( smart wrist band) as the user needs to change the electrode or wash it after a while of usage.
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.
During doing cyclic voltammetry in three electrodes system (reference electrode, contour or auxiliary electrode, and the Au working electrode), tiny bubbles form at the surface of the Au working electrode. Does anyone have any suggestions about how to get rid of bubbles without changing the potential window?
We are using screen printed gold electrode(220BT) from Dropsens to build an immunosensor.
To attach the antibody onto the working electrode, we use EDC/NHS with MPA.
From what I understand, we need to restrict the linker and antibody adsorption on working electrode alone. However, many of the paper I read that uses the same electrode only mention they "drop 50 ul of liquid" onto the electrode which got me confused.
From what I can see, any liquid over 10ul will spread from the working electrode and cover the reference and counter electrode but I have not seen much mention of flow chamber or whatever else that can be used to contain the liquid to the working electrode.
Is this something that was just omitted because it is too obvious or is it just common to drop the liquid on to the entire electrode?
If there is an obvious way to isolate the working electrode, could you let me know what it is?
I want to measure the resistance of medium at a fixed frequency by inducing constant ac current and then measuring the voltage drop across the medium. Ag/AgCl pallets are cheaper than Ag/AgCl reference electrodes. What is the actual difference between them and how are they different and what types of experiments are they most suitable for?
Some label free electrochemical biosensors based on affinity events between immobilized antibodies and proteins use the ferricyanide/ferrocyanide redox couple as a redox active probe. These molecules have a negative charge of -3 and -4.
Are there any other redox molecules that perhaps have a positive charge (cation) that can also be used as a probe?
screen printed carbon electrode was characterized using 5 mM Ferricyanide/ 5mM Ferrocyanide with 0.1 M KCL , with scan rate from 10 to 100 mV/s vs Ag/AgCl , why the shift go to the right then to the left?
the relation between the square root of the scan rate and the delta potential( shift) does not linear?
please find the attached attached figures which are :
2- delta vs square root of the scan rate.
First, i coated Hexanedithiol on to the gold surface and then blocking remain gold surface used Mercaptohexanol. After that Benzoquinone was coated on gold surface. We reduced the benzoquinone using electricity. Finaly, thiolated peptide was coated on to the gold. And measured using SWV.
(Buffer-4mM Fe(CN)3-/4- )
Question 1. We can't observed clean peak in SWV. How can i get a clean peak?
Question 2. Some research papers suggest that SWV should measured many times to get stable and clean peaks. Is this suggest
Thank you for interest to my questions.
I have seen many researchers including Prof Alan Bond measure the effective areas by measurement of the peak current obtained as a function of scan rate under linear sweep voltammetric conditions for the one-electron oxidation of Fc [1.0 mM in CH3CN (0.1 M Bu4NPF6)] or reduction of [Fe(CN)6] 3- [1.0 mM in water (0.5 M KCl)] and use of the Randles-Sevcik equation.
The classic IUPAC paper (Trasatti and Petrii 1991, https://www.sciencedirect.com/science/article/pii/002207289280162W) provided us with some other important recommendations in different conditions (one example is via reduction of gold oxide)!
I would like to know whether there are any disadvantages of using the Randles-Sevcik equation for measuring the area? Do you prefer any other methods over this one while working with a reversible reaction on gold disk electrode?
I have gold nanoparticles suspension in citrate buffer and i want to modify the WE of screen printed electrode with is particles using thiosalicylic acid , if any one faced similar work, please give me guidelines or the protocol was used.
Am working on a DNA based biosensor, DNA are thiolated. i reduce thiolated ssDNA by TCEP and dip cast it on a gold nanoparticle coated electrode.
I have tried with 500nM , 1uM, 2uM, 3uM, 4uM and 5uM concentrations, but am not getting a constant value by DPV.
i use methylene blue as indicator, should i have to refrigerate the methylene blue after use.
i need to fix the probe concentration.
Can some one share their insights on this, that would be great help.
i have carbon screen printed electrode and gold nano particles suspension in citrate buffer, how to deposit the particles on the electrode in a way to get uniform distribution?
I am looking into electrochemical biosensors based on square wave voltammetry and cyclic voltammetry. These sensors usually use potassium ferricyanide/ferrocyanide as the electroactive species in an electrolytic solution such as phosphate buffer saline (PBS). Most articles site that a concentration of 5 mM potassium ferricyanide in PBS is used for conducting voltammetry experiments, but I would like to increase this to about 10 mM in PBS to improve my signal to noise ratio.
I was wondering what effect this would have on the proteins, such as antibodies, on the surface of the sensor? Could denaturation of antibodies and target proteins occur when the concentration is too high?
hello all ,
in my lab i have PGZ100( EIS Maximum frequency 100 kHz , Best current resolution 30 pA, Scan rate 0.5 V/s , Lowest current range 1 µA , Frequencies/decade 5,10,15)
does this potentiostat suitable for biosensor characterization? and how i can judge if it good for my work or i have to use another potenntiostat?
Currently Iam working on amperometric biosensor using SPCE (screen printed carbon electrode) but I still confuse to figure out what is the different between this electrode with Interdigitated array electrode (IDA) since I want to know whether I can work at the same condition between these two.
I have recorded the CVs at different scan rate (100-1000 mV) and plotted the graphs for Peak current Vs square root of scan rate. I have found it non linear. Why it is? Is it showing that the ongoing electrochemical reaction process is irreversible? When i have plotted the Peak current Vs scan rate, it is slightly linear. Why the change occurs? I need the exact reason behind this. Kindly suggest (with reference if possible).
I have attached the file for reference.
Recently, I have been working on AOR. I have obtained interesting results, however, the result is a bit disturbing as it comes with noise in the curve. Below is a picture of such. I have read up some of the suggestions presented to similar circumstances in RDE measurement for ORR. I have not been able to overcome the challenge. For my circumstance, am working using Pt wire/coil as counter, Ag/AgCl as reference and GC as working electrode in 1M NaOH.
1. No leakage in RE as I have checked a couple of times and I have about 3 of these REs at my disposal, so I can interchange and check if there is any leakage (issues) with either of them. The aligator clips look good and have also interchanged with spare.
2. No mechanical vibration / interference as the lab is set up in the basement of the building and the experimental setup is on a standardized experimental bench. In addition, am not working on a hanging electrode.
3. From the picture, I have worked between -0.7eV and 0.6eV. However, I do work also in the range of 0eV and 1.4eV
4. The experimental solution has been prepared hours prior to the the measurement, and given enough time to acclimatize to the room temperature. As regard to the GC electrodes, I follow the standard rules. Polishing via the "8" pattern using 0.05um polishing alumina once in 5 days on the polish and DIW for rinsing.
Do you have any other suggestion?
is there any publish research show the salivary biomarkers concentration for breast cancer?
iam trying to design a salivary biosensor for early detection of breast cancer. recommend me some articles please
I have an electrolyte membrane (~ 200 μm thick) containing Nafion and ionic liquid (EMIM-BF4 ). I want to check ions transfer inside the membrane when it is subjected to an electric field. I'm wondering if there is any way for real-time monitoring of the cations and anions movements toward corresponded electrodes.
Biosensors and Bioelectronics 25 (2010) 1301–1306 ; they also calculated the same parameter but i am confused with the units that they put into the equation!
If Beethoven was alive today, which technology would help him to hide deafness?
According to statistics, 80% of those who could benefit from a hearing-aid choose not to use one. One of the most important reasons for that, is the social stigma associated with common misconceptions about wearing hearing aids. How can bioMEMS help to fabricate miniaturized hearing aids without compromising performance?
My work is on biomolecule sensing by potentiometry (CA, CV, etc.). Concentration of each individual biomolecule can be easily monitored by variation in current or voltage, but how to check selectivity i.e. which specific biomolecule is present in a mixture of different biomolecules. In case of heavy metals the redox potential difference is high which is not the case in biomolecules. So please suggest me how to sense or discriminate specific biomolecule (ex. amino acid).
I'm working on an electrochemical biosensor integrated into a microfluidic system. The working and counter electrodes are gold, and the reference electrode is Ag/AgCl.
I'm planning to either immobilize thiolized nucleic acids on the bare gold WE surface, or use 11-mercaptoundecanoic acid SAM method to functionalize the WE surface for EDC-NHS coupling to proteins.
Due to the way the microfluidic device is fabricated, I may need to immobilize the biorecognition probes within closed channels (post-bonding). I also want to functionalize only the WE, while keeping the CE/RE uncoated.
Can anyone guide me on how this can be done?
We have transgenic E. coli and we need to isolated and purified the specific protein. We used membrane filtres, however it didn't work as we expected. We don't want to use chromatography for purification, first. I just looking for some other alternatives.
Thank you for response.
1. The system consists of a protein complexed on thiolated SAM (mercaptohexadecanoic acid) after activation with EDC (carbodiimide). The immobilization is done on a gold coated slide which is the working electrode (WE). The electrode area ~ 1 cm-2.
2. Reference electrode is Ag/AgCl wire and counter electrode (CE) is a Platinum wire.
The protein is further complexed with a DNA aptamer.
Then successive EIS scans were run on the system with 1mm Ferro/Ferri redox couple in 1 X PBS.
However, the system is not stabilizing over more than 2 hours. The Rct and Cdl keep on increasing.
EIS parameters : Freq range : 10 KHz to 0.1 Hz ; AC voltage 5 mV ; No DC voltage
Relevant figures are attached.
What could be the reason behind the drift of the system ? What could be a possible solution. I can wait for longer times but would like to fix this problem.
Hi Everyone, Am looking for a Methods / Protocols for Electrochemical Biosensors, can some one shed the light on these aspects,since am new to Electrochemical biosensors , my aim is to build a Electrochemical Biosensor to detect microbial pathogens.
I am facing a big problem regarding fitting and modeling my impedance data. I am using a non-Faradaic system (only filtered and degassed 10 mM PBS solution) for the EIS measurement of gold disk electrode (1.6 mm diameter) modified with SAM, linker, and proteins. I am using the modified Randles' circuit model to fit the impedance curve and get the Rct to plot the dose response curve of my sensor but some paper say that Rct for the non-Faradaic system are too big and almost neglected, usually, the capacitance is used to interpret data. I couldn't find relevant papers using this kind of system and still not sure whether my circuit model is correct for my system or not. Could anyone be able to explain this situation better???
I haven't been able to find a "field applicable" phosphate sensor in the market yet. Seems there are many unsolved challenges such as longevity, signal drift, selectivity, etc for this sensor in field. Do you know of any commercially developed field applicable phosphate sensors? Or the reasons why this type of sensor is hard to develop for field applications? Thanks
I just bought the QCM cell from CH instrument and I do not know how to use it in parallel with Cyclic Voltammetry. I am using CV for metal-decorated graphene to enhance the electrode sensitivity toward selective biological metabolite.
i am working on electrochemical detection of DNA and proteins after adsorption of Fc-DNA probe or Fc-aptamers on reduced graphene oxide modified electrodes. But, the sqaure wave voltammetry signal is not stable with time. always there is 5 to 10% decrease in the swv signal which cannot be used for further measurement. does anyone saw this issue before and how can we figure out it. many publications have been published in this field bit none talk about the stability of the adsorbed DNA containing redox tag.
I've been running EIS on gold chips with the surface modified with thiol SAM and antibody fragments etc.
Some of my EIS runs result in impedance of ~5000-1000 ohms, but then others shoot up to ~30,000-50,000 ohms. Despite all being treated and produced in the same way. My supervisor also made chips himself and ran them with the same issue.
Any ideas what might cause such a dramatic increase??
Currently I work with SPGE (screen printed gold electrode) but I still confuse to figure out what is the different between this electrode with Interdigitated array electrode (IDA) since I want to know whether I can work at the same condition between these two.
I am working on electrochemical non-enzymatic glucose sensor. I don't know how to measure glucose amount present in the blood and blood serum. How I compare my result with the standard analytical kit result ? Is there any method to detect it and Weather I have to do IT measurement or any measurement? Please help me.
What are the arguments of making a distinction between the CE and RE if I am measuring non-faradaic processes (i.e. binding events to a surface modified WE)? I understand the arguments for faradaic measurements, that the CE allows current to pass while to ensure the RE can maintain a constant potential. However, if no current is flowing across my electrode interface(s), why would a 3-electrode benefit?
In electrochemical cells where reference electrodes are thin films and are not in contact with standard saturated solutions, how reliable would the readings be in terms of having a stable reference potential?
Hi!, I´m trying to build a low-cost potetiostat using Arduino Uno platform to perform cyclic voltammetry, but I don´t know how to modify the original sketch for other techniques like anodic stripping voltammetry or linear sweep voltammetry.
Do I have to use a different microcontroller or use more than one for this goal?
I am trying to develop electrochemical biosensor using screen printed electrode. The sensor gives good response in blank solutions. However, in presence of proteins, such as albumin, the signal completely disappears. I want to understand if there is a way to prevent protein adsorption, which I believe is distorting the signal.
In an electrochemical reaction O+ne=R, in the anodic direction (R->O+ne), above a certain level of applied potential, system hits the mass transport limit. Then, bulk concentration of O won't change the current density. How can we experimentally test this to make sure that variations in O does not affect current density? I know that sampled current voltammetry gives some clue, but what if the system operates near the limit and even small variations in signal matter?
I am an undergrad student currently researching the use of bacterial biosensors and their potential use for the determination of heavy metal contaminants in environmental water samples.
Brief system description :
Gold coated glass slide is the working electrode. Used an Al foil clamped to the Au coated glass for connecting to the working electrode of the potentiostat. A part of the gold surface is used for holding a 1 ml drop of 1mM ferro/ferri cyanide in 1X PBS buffer.
Ag/AgCl is used as a reference electrode and Platinum wire is used as counter electrode.
1) Firstly EIS with 5 mV AC perturbation was done on the Au coated glass slide. (bare)
2) Then the electrolyte from the surface was removed and 300 micro liter of 3 mM mercaptohexanol was immobilized for 1 hour. Then it was washed in dd water, dried in air and again the ferro/ferricyanide in 1X PBS was put in. EIS is run with the same parameters as step 1.
3) The SAM layer immobilized Au coated glass slide was heated in acetone solution at 70oC, washed in water and step 1 was repeated.
According to my hypothesis SAM layer will increases the impedance and thus increase the "charge transfer " resistance. However, I am observing the reverse phenomenon for my system.
The plot is attached.
What could be the cause ?
Reference for hypothesis :
Shinn-Jyh Ding, Bin-Wha Chang, Ching-Chou Wu, Min-Feng Lai, Hsien-Chang Chang, Impedance spectral studies of self-assembly of alkanethiols with different chain lengths using different immobilization strategies on Au electrodes, Analytica Chimica Acta, Volume 554, Issues 1–2, 4 December 2005, Pages 43-51, ISSN 0003-2670, http://dx.doi.org/10.1016/j.aca.2005.08.046.
I want to test the antioxidant capacity of plant-derived alkaloids (conjugated with gold naoparticles by green synthesis) on electrochemical biosensor using Xanthine Oxidase-Superoxide Dismutase enzyme system. What could be the best strategy for screen printed electrode?
When I used oxygen plasma treatment for sticking PDMS to glass substrate which has Au-Cr electrodes, the electrodes became damage. How can I solve this problem?
In the attached photo, the device which was used for making plasma is shown.
I have a device resembling the one in the attached image. I want to measure the current across the two Ag/AgCl electrodes separated by the membrane at different voltages (e.g. +200 mV , -200 mV) etc.
The membrane is Au coated and is nanoporous in nature. It will be immobilized with organic molecules in later experiments.
I have a Gamry Potentiostat in my lab which has a program called set voltage. Can I use that for performing the experiment ?
I am unsure about the technique as I have little or less knowledge in electrochemistry.
I am performing sandwich ELISA to detect biomarkers (as antigens).
The cyclic voltammetry(CV) of the the SPCE is taken to analyze the analyte (biomarker).
The primary antibody is immobilized onto the working electrode.
What are best way to chemically pre-treat carbon electrodes before using EDC-NHS.
What chemicals are suitable for this pretreatment?
I appreciate your time. Please reply.
Hello, I' m searching for details about graphene based biosensors for the detection of glucose. Can anyone tell me about the electronic properties related to the application and if there are any factors that limit the deployment of graphene in glucose biosensing? My research is referring to non-composite graphene biosensors. The most research papers I studied refer to graphene oxide or praphene composites.
Thank you in advance