Deposition of nanomaterials: A crucial step in biosensor fabrication

TLDR: In this article, the authors summarized the methods used for (nano)material deposition onto an electrode surface for efficient biosensor fabrication and discussed the problems faced during biosensor application as well as the present challenges and prospects for superior deposition methods.

Abstract: Biosensor development includes the deposition of (nano)materials onto a conductive electrode surface, which is a crucial step for obtaining improved performance from the constructed biosensors. Various methods have been used to create a successful matrix of (nano)materials that ensures proper contact between the material and electrode surface. The purpose of (nano)material deposition is to provide a high surface area to improve the electroanalytical performance of biosensors by supporting the stable immobilization of enzymes in a more significant quantity as well as enhancing the catalytic or bioaffinity features. For decades, researchers have been using increasingly advanced methods not only for improving sensing performance, but also for improving stability, reproducibility, and mass production. In this review, we summarized the methods used for (nano)material deposition onto an electrode surface for efficient biosensor fabrication. An enhanced and optimized (nano)material deposition method is crucial for the mechanical stability and fabrication reproducibility of electrodes when designing a suitable biosensing device. In addition, we discussed the problems faced during biosensor application as well as the present challenges and prospects for superior deposition methods.

Figures

Fig. 7. Schematic showing the modification of an electrode with rGO, PPy, Cu, and CuxO for glucose sensor fabrication (reproduced with permission from ref. [226], Copyright 2015 Elsevier)

Frequently asked questions

Q1. What contributions have the authors mentioned in the paper "Deposition of nanomaterials: a crucial step in biosensor fabrication" ?

The purpose of ( nano ) material deposition is to provide a high surface area to improve the electroanalytical performance of biosensors by supporting the stable immobilization of enzymes in a more significant quantity as well as enhancing the catalytic or bioaffinity features. In this review, the authors summarized the methods used for ( nano ) material deposition onto an electrode surface for efficient biosensor fabrication. In addition, the authors discussed the problems faced during biosensor application as well as the present challenges and prospects for superior deposition methods. 

Q2. What are the common methods used for modifying biosensors?

Coating-based methods (i.e., drop casting, dip coating, spin coating, and bladecoating) are most commonly used for modifying electrodes with nanomaterials. 

Q3. What is the importance of the LSG method for a single-step biosensor?

Considering flexible, disposable, and paper-based device fabrication, the LSG method is critical for single-step biosensor development. 

Q4. What is the main contributing factor for the excellent glucose sensing performance?

The 3D network architecture of the electrode surface and synergistic effects of the conductive carbon nanofibers and NiCo2O4 nanoneedles were the main contributing factors for the excellent glucose sensing performance. 

Q5. What are the main methods used to grow nanomaterials on electrode surfaces?

To grow the nanomaterials and tailor the electrode surface, various methods have been utilized, such as hydrothermal, thermal decomposition, template, anodization, and chemical decomposition. 

Q6. What are the advantages of the direct growth of nanomaterials on electrode surfaces?

because of the direct growth of NRs on the electrode surface, good stability and direct electron transfer from NRs to the electrode led to a faster response and higher sensitivity. 

Q7. What is the main limitation of drop-casting?

The major limitation of drop-cast sensors is the fact that enzymes and antibodies can only be deposited (cast) onto the electrode surface from aqueous solutions. 

Q8. What are the electrochemical parameters used for coating the nanostructure?

The nanostructure morphology, thickness, and uniformity of the coated films can be precisely controlled using alterable electrochemical parameters (i.e., potential, additive, current, temperature, and pH). 

Q9. What was the main reason for the fabricated electrodes?

the fabricated electrodes were binder-free, disposable, cost-effective, environmentally benign, and showed potential application in serum samples. 

Q10. What are the different printing methods used to deposit nanomaterials?

The range of printing methods is utilized to deposit nanomaterials, which includes the old and well-known screen-printing method as well as the recently developed inkjet printing, nozzle-jet printing, and laser-scribing process. 

Q11. What was the process used to print the carbon paste electrodes?

The carbon paste working electrodes printed using screen-printing were over-printed with conductive polymer PANI hydrogel followed by enzyme printing using the “drop-on-demand” method onto the printed working electrode. 

Q12. What are the key characteristics for controlling the quality of the deposited films?

They determined that the rheological parameters (viscosity, concentration, and conductivity) were the crucial features for controlling the quality of the deposited films. 

Q13. What is the preferred method for creating controlled, uniform, and thick films?

The spin-coating process is preferred over the drop-/dip-coating techniques for creating controlled, uniform, and thick/multilayer films. 

Q14. What other materials have been directly grown and successfully used to fabricate biosensors?

Several other nanomaterials, such as a Cu2+1O nanocubes/graphene nanosheet hybrid on Cu foam [435], cuprous sulfide (CuS) NRs on Cu foam [436], TiO2 NRs on graphite microfiber [437], and silver oxide (Ag2O) nanowalls on a Cu substrate [438], have been directly grown and successfully used to fabricate biosensors. 

Q15. What are the advantages of nanomaterials on electrode surfaces?

The direct growth of nanomaterials on the electrode surface fulfill these requirements by providing a large surface area with exposed catalytic sites; enhanced mechanical contact between nanomaterials and the electrode surface, which facilitates electronic transfer and offer improved stability; an excellent microenvironment for immobilized enzymes; and accessibility of electrolytes and target analytes during sensing applications. 

Q16. What are the key parameters for obtaining high sensitivity and improved response times from biosensors?

selecting an ideal electrode, active nanomaterial, and nanomaterial deposition method are critical parameters for obtaining high sensitivity and improved response times from biosensor devices. 

Q17. How can high viscosity resins/inks be printed?

High viscosity resins/inks can be printed using a nozzle-jet printing system when applying a high nozzle pressure or using a large nozzle tip. 

Q18. What are the main advantages of direct deposit/growth-based methods?

To date, several methods have been successfully applied to directly deposit/grownanomaterials onto electrode surfaces, and they have been widely used in various applications, including biosensor fabrication.