We review the progress achieved during the recent five years in immunochemical biosensors (immunosensors) combined with nanoparticles for enhanced sensitivity. The initial part introduces antibodies as classic recognition elements. The optical sensing part describes fluorescent, luminescent, and surface plasmon resonance systems. Amperometry, voltammetry, and impedance spectroscopy represent electrochemical transducer methods; electrochemiluminescence with photoelectric conversion constitutes a widely utilized combined method. The transducing options function together with suitable nanoparticles: metallic and metal oxides, including magnetic ones, carbon-based nanotubes, graphene variants, luminescent carbon dots, nanocrystals as quantum dots, and photon up-converting particles. These sources merged together provide extreme variability of existing nanoimmunosensing options. Finally, applications in clinical analysis (markers, tumor cells, and pharmaceuticals) and in the detection of pathogenic microorganisms, toxic agents, and pesticides in the environmental field and food products are summarized.

Nanoparticle-Based Immunochemical Biosensors and Assays: Recent Advances and Challenges

The electrochemical biosensor is one of the typical sensing devices based on transducing the biochemical events to electrical signals. In this type of sensor, an electrode is a key component that is employed as a solid support for immobilization of biomolecules and electron movement. Thanks to numerous nanomaterials that possess the large surface area, synergic effects are enabled by improving loading capacity and the mass transport of reactants for achieving high performance in terms of analytical sensitivity. We categorized the current electrochemical biosensors into two groups, carbon-based (carbon nanotubes and graphene) and non-carbon-based nanomaterials (metallic and silica nanoparticles, nanowire, and indium tin oxide, organic materials). The carbon allotropes can be employed as an electrode and supporting scaffolds due to their large active surface area as well as an effective electron transfer rate. We also discussed the non-carbon nanomaterials that are used as alternative supporting components of the electrode for improving the electrochemical properties of biosensors. Although several functional nanomaterials have provided the innovative solid substrate for high performances, developing on-site version of biosensor that meets enough sensitivity along with high reproducibility still remains a challenge. In particular, the matrix interference from real samples which seriously affects the biomolecular interaction still remains the most critical issues that need to be solved for practical aspect in the electrochemical biosensor.

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Electrochemical biosensors: perspective on functional nanomaterials for on-site analysis.

https://iopscience.iop.org/article/10.1149/2.0291807jss/pdf

Review-field-effect transistor biosensing: Devices and clinical applications

Internet of medical things (IoMT)-integrated biosensors for point-of-care testing of infectious diseases.

Silicon nanowire biosensors for detection of cardiac troponin I (cTnI) with high sensitivity.

This paper reports high performance ion-sensitive field-effect transistors (ISFETs) with a suspended honeycomb nanowire (SHNW) structure. The SHNW can provide a longer, stiction-free channel than that which is possible with a suspended straight nanowire (SSNW) for the realization of gate-all-around biosensors. Devices with SHNWs, SSNWs and conventional nanowires on the substrate have been fabricated using a top-down approach in order to compare their electrical performances. The SHNW devices exhibit excellent electrical characteristics such as lower subthreshold swing, higher transconductance and higher linear drain current. In addition, the SHNW ISFETs show better pH sensitivity than other ISFETs. Based on the results, the SHNW device appears promising for enhancing the intrinsic performance and ensuring the reliable operation of biosensor applications.

https://iopscience.iop.org/article/10.1088/0957-4484/25/34/345501/pdf

Suspended honeycomb nanowire ISFETs for improved stiction-free performance

Au nanoparticle (AuNP)-decorated silicon nanowire (SiNW) field-effect transistors (FETs) were made using a top-down technique to enhance the sensing responses and long-term reliability for the detection of ammonia (NH3). The as-fabricated, diluted hydrofluoric acid (dHF)-treated, and AuNP-decorated SiNW FETs were prepared and characterized at room temperature. These SiNW FETs show better sensitivity and low power consumption in the subthreshold regime than in the linear regime. To evaluate the long-term responses, devices were operated over a period of 120 days. The dHF-treated SiNW FET showed a significant degradation in sensitivity as a function of time, even though it showed the highest sensitivities in the initial stage. The SiNW with AuNPs showed the lowest long-term variation of sensitivity with sufficient linearity. The SiNW with AuNPs showed the lowest drift as low as −0.067%/day for current sensitivity and −0.024%/day for voltage sensitivity, respectively. These results suggest that the deposition of AuNPs on SiNW is very useful for improving the long-term variation in chemical sensing applications.

Improved Long-Term Responses of Au-Decorated Si Nanowire FET Sensor for NH 3 Detection

This paper presents a portable low-cost biosensor platform for ion-sensitive field-effect transistor (ISFET) and enzyme-based sensors. To meet various demands of diagnosis, our portable platform is designed to perform cyclic voltammetry, amperometry, and linear sweep voltammetry for enzyme-based sensor and ISFET sensor. For compatibility with various sensors which require various electrical driving schemes, our system can be easily reconfigured by simple switches. In addition, with disposable printed-circuit-board packages, sensors can be easily replaced. Our platform was tested with various sensors in various measurement methods. In cyclic voltammetry test with a model analyte K3Fe(CN)6, a graph provided by our system has 4.79% relative error at a current peak compared with the data acquired by a 18 times more expensive commercial system. In cyclic voltammetry and amperometry tests with the laccase enzyme-based sensors, our system achieved sensitivities of 341 and 500 $\mu \text{A}$ /mM/cm2, respectively. By running a sensitive SiNW ISFET on our platform in linear sweep voltammetry, we could build a low-cost portable pH sensor system.

A Reconfigurable and Portable Highly Sensitive Biosensor Platform for ISFET and Enzyme-Based Sensors

Highly sensitive silicon-nanonet biologically active field-effect transistors (BioFETs) for the detection of influenza A (H1N1) virus have been demonstrated using a top-down process. The BioFETs show excellent intrinsic electrical characteristics, such as a low threshold voltage of 0.7 V and high on/off current ratio of ~107. The sensing characteristics were measured at room temperature with various concentrations of H1N1 virus in a range of 10 pg/ml - 100 ng/ml. The current-related sensitivity ( ${S}_{ {I}}$ ) shows a higher value in the subthreshold regime, where ${S}_{ {I}}$ is strongly correlated with the subthreshold swing ( SS ). The voltage-related sensitivity ( ${S}_{ {V}}$ ) shows almost constant behavior from the subthreshold regime to the linear regime. The limit of detection (LOD) was 10 pg/ml, which is 6 times lower than values previously reported for FET-type sensors. In addition, the nanonet sensors exhibit high specificity to influenza A virus with negligible false positive for influenza B virus.

Chanoh Park

Papers

Silicon nanowire biosensors for detection of cardiac troponin I (cTnI) with high sensitivity.

Suspended honeycomb nanowire ISFETs for improved stiction-free performance

Improved Long-Term Responses of Au-Decorated Si Nanowire FET Sensor for NH 3 Detection

A Reconfigurable and Portable Highly Sensitive Biosensor Platform for ISFET and Enzyme-Based Sensors

Highly Sensitive Detection of Influenza A (H1N1) Virus With Silicon Nanonet BioFETs