Toward High-Performance Self-Powered Near-Ultraviolet Photodetection by Constructing a Unipolar Heterojunction.

Constructing a unipolar heterojunction is an effective energy band engineering strategy to improve the performance of photoelectric devices, which could suppress dark current and enhance detectivity by modulating the transfer of carriers. In this work, unipolar heterojunctions of Si/PbI2 and GaSb/PbI2 are constructed successfully for high-performance self-powered near-ultraviolet photodetection. Owing to the unique band offset of unipolar heterojunctions, the transport of holes is blocked, and only photogenerated electrons in PbI2 can flow unimpeded under the driving force of the built-in electric field. Thus, the recombination of photogenerated electron-hole pairs is suppressed, contributing to high-performance near-ultraviolet photodetection. The as-fabricated Si/PbI2 self-powered near-ultraviolet photodetector exhibits a low dark current of 10-13 A, a high Ilight/Idark ratio of 104, and fast response times of 26/24 ms, which are much better than those of the PbI2 metal-semiconductor-metal photodetector. Furthermore, the as-fabricated GaSb/PbI2 unipolar heterojunction photodetector also exhibits impressive self-powered near-ultraviolet photodetection behaviors. Evidently, this work shows the potential of unipolar heterojunctions for next-generation Si-based and GaSb-based high-performance photodetection.

Tunable Contacts of Bi2 O2 Se Nanosheets MSM Photodetectors by Metal-Assisted Transfer Approach for Self-Powered Near-Infrared Photodetection.

Owing to the Fermi pinning effect arose in the metal electrodes deposition process, metal-semiconductor contact is always independent on the work function, which challenges the next-generation optoelectronic devices. In this work, a metal-assisted transfer approach is developed to transfer Bi2 O2 Se nanosheets onto the pre-deposited metal electrodes, benefiting to the tunable metal-semiconductor contact. The success in Bi2 O2 Se nanosheets transfer is contributed to the stronger van der Waals adhesion of metal electrodes than that of growth substrates. With the pre-deposited asymmetric electrodes, the self-powered near-infrared photodetectors are realized, demonstrating low dark current of 0.04 pA, high Ilight /Idark ratio of 380, fast rise and decay times of 4 and 6 ms, respectively, under the illumination of 1310 nm laser. By pre-depositing the metal electrodes on polyimide and glass, high-performance flexible and omnidirectional self-powered near-infrared photodetectors are achieved successfully. This study opens up new opportunities for low-dimensional semiconductors in next-generation high-performance optoelectronic devices.

Radiomics for Predicting Response of Neoadjuvant Chemotherapy in Nasopharyngeal Carcinoma: A Systematic Review and Meta-Analysis.

Purpose: This study examined the methodological quality of radiomics to predict the effectiveness of neoadjuvant chemotherapy in nasopharyngeal carcinoma (NPC). We performed a meta-analysis of radiomics studies evaluating the bias risk and treatment response estimation. Methods: Our study was conducted through a literature review as per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We included radiomics-related papers, published prior to January 31, 2022, in our analysis to examine the effectiveness of neoadjuvant chemotherapy in NPC. The methodological quality was assessed using the radiomics quality score. The intra-class correlation coefficient (ICC) was employed to evaluate inter-reader reproducibility. The pooled area under the curve (AUC), pooled sensitivity, and pooled specificity were used to assess the ability of radiomics to predict response to neoadjuvant chemotherapy in NPC. Lastly, the Quality Assessment of Diagnostic Accuracy Studies technique was used to analyze the bias risk. Results: A total of 12 studies were eligible for our systematic review, and 6 papers were included in our meta-analysis. The radiomics quality score was set from 7 to 21 (maximum score: 36). There was satisfactory ICC (ICC = 0.987, 95% CI: 0.957-0.996). The pooled sensitivity and specificity were 0.88 (95% CI: 0.71-0.95) and 0.82 (95% CI: 0.68-0.91), respectively. The overall AUC was 0.91 (95% CI: 0.88-0.93). Conclusion: Prediction response of neoadjuvant chemotherapy in NPC using machine learning and radiomics is beneficial in improving standardization and methodological quality before applying it to clinical practice.

Mechanism, Material, Design, and Implementation Principle of Two-Dimensional Material Photodetectors.

Two-dimensional (2D) materials may play an important role in future photodetectors due to their natural atom-thin body thickness, unique quantum confinement, and excellent electronic and photoelectric properties. Semimetallic graphene, semiconductor black phosphorus, and transition metal dichalcogenides possess flexible and adjustable bandgaps, which correspond to a wide interaction spectrum ranging from ultraviolet to terahertz. Nevertheless, their absorbance is relatively low, and it is difficult for a single material to cover a wide spectrum. Therefore, the combination of phototransistors based on 2D hybrid structures with other material platforms, such as quantum dots, organic materials, or plasma nanostructures, exhibit ultra-sensitive and broadband optical detection capabilities that cannot be ascribed to the individual constituents of the assembly. This article provides a comprehensive and systematic review of the recent research progress of 2D material photodetectors. First, the fundamental detection mechanism and key metrics of the 2D material photodetectors are introduced. Then, the latest developments in 2D material photodetectors are reviewed based on the strategies of photocurrent enhancement. Finally, a design and implementation principle for high-performance 2D material photodetectors is provided, together with the current challenges and future outlooks.

Film wrap nanoparticle system with the graphene nano-spacer for SERS detection.

Film wrap nanoparticle system (FWPS) is proposed and fabricated to perform SERS effect, where the Ag nanoparticle was completely wrapped by Au film and the double-layered graphene was selected as the sub-nano spacer. In this system, the designed nanostructure can be fully rather than partly used to generate hotspots and absorb probe molecules, compared to the nanoparticle to nanoparticle system (PTPS) or nanoparticle to film system (PTFS). The optimal fabricating condition and performance of this system were studied by the COMSOL Multiphysics. The simulation results show that the strongly large-scale localized electromagnetic field appears in the whole space between the Ag nanoparticle and Au film. The experimental results show that the FWPS presents excellent sensitivity (crystal violet (CV): 10-11 M), uniformity, stability and high enhancement factor (EF: 2.23×108). Malachite green (MG; 10-10 M) on the surface of fish and DNA strands with different base sequence (A, T, C) were successfully detected. These advanced results indicate that FWPS is highly promising to be applied for the detection of environmental pollution and biomolecules.

Plasma treated graphene FET sensor for the DNA hybridization detection.

Room-temperature plasma treated graphene based FET was firstly proposed for the DNA hybridization detection. Affinity and electrical properties of the graphene based DNA-FET sensor were studied and improved benefits from the surface modification. The facile room-temperature Ar plasma easily removes residues from the graphene surface and changes the hydrophilic properties of graphene, which is important for our solution gated DNA-FET sensor. Limit of the detection of below 10 aM is obtained in our experiment. Especially, DNA concentration (CDNA)/the amount of net drain current (ΔI) and the negative shift in the VCNP value of the GFET sensor with the plasma treated 30 s are all improved compared with that without treatment. It shows that the easily plasma treatment of the graphene surface can be used for the solution gated FET sensor.

A novel acetylcholinesterase biosensor based on carboxylic graphene coated with silver nanoparticles for pesticide detection.

A novel acetylcholinesterase (AChE) biosensor based on Ag NPs, carboxylic graphene (CGR) and Nafion (NF) hybrid modified glass carbon electrode (GCE) has been successfully developed. Ag NPs-CGR-NF possessed predominant conductivity, catalysis and biocompatibility and provided a hydrophilic surface for AChE adhesion. Chitosan (CS) was used to immobilize AChE on the surface of Ag NPs-CGR-NF/GCE to keep the AChE activities. The AChE biosensor showed favorable affinity to acetylthiocholine chloride (ATCl) and could catalyze the hydrolysis of ATCl with an apparent Michaelis-Menten constant value of 133 µM, which was then oxidized to produce a detectable and fast response. Under optimum conditions, the biosensor detected chlorpyrifos and carbaryl at concentrations ranging from 1.0×10(-13) to 1×10(-8) M and from 1.0×10(-12) to 1×10(-8) M. The detection limits for chlorpyrifos and carbaryl were 5.3×10(-14) M and 5.45×10(-13) M, respectively. The developed biosensor exhibited good sensitivity, stability, reproducibility and low cost, thus providing a promising tool for analysis of enzyme inhibitors. This study could provide a simple and effective immobilization platform for meeting the demand of the effective immobilization enzyme on the electrode surface.

Development of a biosensor based on immobilization of acetylcholinesterase on NiO nanoparticles-carboxylic graphene-nafion modified electrode for detection of pesticides.

A sensitive amperometric acetylcholinesterase (AChE) biosensor based on NiO nanoparticles (NiO NPs), carboxylic graphene (CGR) and nafion (NF) modified glassy carbon electrode (GCE) has been developed. NiO NPs-CGR-NF nanocomposites with excellent conductivity, catalysis and biocompatibility offered an extremely hydrophilic surface for AChE adhesion. The AChE biosensor showed favorable affinity to acetylthiocholine chloride (ATCl) and could catalyze the hydrolysis of ATCl with an apparent Michaelis-Menten constant value of 135 µM. Under optimum conditions, the biosensor detected methyl parathion and chlorpyrifos in the linear range from 1.0 × 10(-13) to 1 × 10(-10)M and from 1.0 × 10(-10) to 1 × 10(-8)M with the detection limits 5 × 10(-14)M. The biosensor detected carbofuran in the linear range from 1.0 × 10(-12) to 1 × 10(-10)M and from 1.0 × 10(-10) to 1 × 10(-8)M with the detection limit of 5 × 10(-13)M. The developed biosensor exhibited good sensitivity, stability and reproducibility, thus providing a promising tool for analysis of enzyme inhibitors.

Acetylcholinesterase biosensor based on SnO2 nanoparticles-carboxylic graphene-nafion modified electrode for detection of pesticides.

A sensitive amperometric acetylcholinesterase (AChE) biosensor, based on SnO2 nanoparticles (SnO2 NPs), carboxylic graphene (CGR) and nafion (NF) modified glassy carbon electrode (GCE) for the detection of methyl parathion and carbofuran has been developed. The nanocomposites of SnO2 NPs and CGR was synthesized and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), respectively. Chitosan (CS) was used to immobilize AChE on SnO2 NPs-CGR-NF/GCE and to improve electronic transmission between AChE and SnO2 NPs-CGR-NF/GCE. NF was used as the protective membrane for the AChE biosensor. The SnO2 NPs-CGR-NF nanocomposites with excellent conductivity, catalysis and biocompatibility offered an extremely hydrophilic surface for AChE adhesion. The AChE biosensor showed favorable affinity to acetylthiocholine chloride (ATCl) and could catalyze the hydrolysis of ATCl with an apparent Michaelis-Menten constant value of 131 µM. The biosensor detected methyl parathion in the linear range from 10(-13) to 10(-10)M and from 10(-10) to 10(-8)M. The biosensor detected carbofuran in the linear range from 10(-12) to 10(-10)M and from 10(-10) to 10(-8)M. The detection limits of methyl parathion and carbofuran were 5 × 10(-14)M and 5 × 10(-13)M, respectively. The biosensor exhibited low applied potential, high sensitivity and acceptable stability, thus providing a promising tool for analysis of pesticides.

An acetylcholinesterase biosensor based on platinum nanoparticles-carboxylic graphene-nafion-modified electrode for detection of pesticides.

A sensitive amperometric acetylcholinesterase (AChE) biosensor based on platinum nanoparticles (Pt NPs), carboxylic graphene (CGR), and nafion (NF)-modified glassy carbon electrode (GCE) has been developed. The Pt NPs-CGR-NF nanocomposites with excellent conductivity, catalysis, and biocompatibility offered an extremely hydrophilic surface for AChE adhesion. Chitosan (CS) was used as cross-linker to immobilize the AChE on Pt-CGR-NF-modified GCE. NF was used as a protective membrane of the AChE biosensors. The AChE biosensor showed favorable affinity to acetylthiocholine chloride (ATCl) and could catalyze the hydrolysis of ATCl with an apparent Michaelis-Menten constant value of 148µM. Under optimum conditions, the biosensor detected methyl parathion in the linear range from 1.0×10(-13) to 1×10(-10)M and from 1.0×10(-10) to 1×10(-8)M with a detection limit of 5×10(-14)M and detected carbofuran in the linear range from 1.0×10(-12) to 1×10(-10)M and from 1.0×10(-10) to 1×10(-8)M with a detection limit of 5×10(-13)M. The biosensor exhibited good sensitivity, acceptable stability, and reproducibility, thus providing a promising tool for analysis of enzyme inhibitors.

Development of a stable biosensor based on a SiO2 nanosheet-Nafion-modified glassy carbon electrode for sensitive detection of pesticides.

SiO(2) nanosheets (SNS) have been prepared by a chemical method using montmorillonite as raw material and were characterized by scanning electron microscopy and X-ray diffraction. SiO(2) nanosheet-Nafion nanocomposites with excellent conductivity, catalytic activity, and biocompatibility provided an extremely hydrophilic surface for biomolecule adhesion. Chitosan was used as a cross-linker to immobilize acetylcholinesterase (AChE), and Nafion was used as a protective membrane to efficiently improve the stability of the AChE biosensor. The AChE biosensor showed favorable affinity for acetylthiocholine chloride and catalyzed the hydrolysis of acetylthiocholine chloride with an apparent Michaelis-Menten constant of 134 µM to form thiocholine, which was then oxidized to produce a detectable and fast response. Based on the inhibition by pesticides of the enzymatic activity of AChE, detection of the amperometric response from thiocholine on the biosensor is a simple and effective way to biomonitor exposure to pesticides. Under optimum conditions, the biosensor detected methyl parathion, chlorpyrifos, and carbofuran at concentrations ranging from 1.0 × 10(-12) to 1 × 10(-10) M and from 1.0 × 10(-10) to 1 × 10(-8) M. The detection limits for methyl parathion, chlorpyrifos, and carbofuran were 5 × 10(-13) M. The biosensor developed exhibited good sensitivity, stability, reproducibility, and low cost, thus providing a new promising tool for analysis of enzyme inhibitors.