Search

Comprehensive Summary: With the advantages of high sensitivity, rapid response, label‐free, and simple operation, field effect transistor biosensors have shown promising application prospects in large‐scale pathogen screening. However, in practical biological fluids with relatively high ionic strength, such as saliva and serum, the Debye screening effect will weaken the interaction between FET biosensors and target bio‐molecules, thereby affecting the sensing sensitivity and accuracy. Herein, an interfacial polymer‐engineered field effect transistor (IPE FET) biosensor was developed for the efficient identification of SARS‐CoV‐2 N antigens in saliva samples. The inclusion of a polymer layer shortens the distance between target molecules and the electrode interface, which effectively overcomes the limitation of Debye screening. The constructed IPE FET biosensors exhibit high sensitivity and anti‐fouling capability, achieving efficient detection of SARS‐CoV‐2 N antigen in saliva within 5 min with a detection limit of 4.6 fg·mL−1. In a cohort of 35 simulated throat swab samples of SARS‐CoV‐2 N antigen, IPE FET exhibits an identification accuracy of up to 97.1%, with predictive sensitivity and specificity of 96.0% and 100.0%, respectively. The excellent performance of IPE FET not only provides a strategy to design efficient detection platforms but also suggests a pathway to realize rapid and scalable epidemic screening. [ABSTRACT FROM AUTHOR]

Monitoring microbial metabolism is vital for revealing the mechanism of disease related to microbial metabolism and providing guidance for biomanufacturing processes optimization. However, it remains a grand challenge to offer real‐time insights into microbial metabolism owing to the complex and dynamic process. In this paper, the recent advances and prospects of optical biosensors including the organic, genetic coding and inorganic optical biosensors are briefly described for real‐time monitoring of dynamic microbial metabolism. This paper points out that challenges remain in microbial heterogeneity. We believe that this work will inspire the application of developing new methods for single cell real‐time analysis. [ABSTRACT FROM AUTHOR]

As a carrier of genetic information, DNA is a versatile module for fabricating nanostructures and nanodevices. Functional molecules could be integrated into DNA by precise base complementary pairing, greatly expanding the functions of DNA nanomaterials. These functions endow DNA nanomaterials with great potential in the application of biomedical field. In recent years, functional DNA nanomaterials have been rapidly investigated and perfected. There have been reviews that classified DNA nanomaterials from the perspective of functions, while this review primarily focuses on the preparation methods of functional DNA nanomaterials. This review comprehensively introduces the preparation methods of DNA nanomaterials with functions such as molecular recognition, nanozyme catalysis, drug delivery, and biomedical material templates. Then, the latest application progress of functional DNA nanomaterials is systematically reviewed. Finally, current challenges and future prospects for functional DNA nanomaterials are discussed. [ABSTRACT FROM AUTHOR]

Persistent luminescence materials (PLMs) are a class of unique luminescent materials that can remain luminescent for a few milliseconds to days without constant excitation. By virtue of the super long decay time, PLMs have been extensively explored in biosensing and bioimaging applications to elimin ate autofluorescence interference and improve signal‐to‐noise ratio in complex samples and tissues. However, nude PLMs often suffer from the poor stability, selectivity, and biocompatibility in biological system and in vivo, which greatly impedes their applications in biomedicine and bioanalysis. Remarkably, surface modification is a viable solution that endows PLMs with span‐new features and can make PLMs suitable for organisms by altering PLMs' interaction with biological system. In this review, commonly used strategies for surface modification of PLMs are briefly introduced, and the applications of surface modified PLMs in biosensing and bioimaging as well as their challenges are summarized. [ABSTRACT FROM AUTHOR]

The simultaneous quantitation of multiple steroid hormones in real time is of great importance in medical diagnosis. In this study, a portable hormone biosensor based on duplex molecular recognition coupled with a signal-amplified substrate was successfully developed for the simultaneous visualization and quantitation of multiple steroid hormones. Aptamer-functionalized upconversion nanoparticles (UCNPs) with different emission peaks are immobilized on the photonic crystal (PC) substrate as the nanoprobes, leading to the specific and simultaneous assay of multiple steroid hormones. Coupled with the luminescence-enhanced effect of the PC substrate, nanomolar quantification limits of multiple hormones are achieved. This well-designed biosensor is also promising in the quantification of multiple hormones in serum samples. The amplified luminescence signals can be visualized with the naked eye and captured by an unmodified phone camera. This hormone quantitation biosensor exhibits the advantages of multi-detection, visualization, high sensitivity, and selectivity for potential applications in clinical disease diagnosis. [ABSTRACT FROM AUTHOR]

Green algae have been studied as an important and effective biomarker to indicate water quality due to their sensitivity to toxic agents in freshwater sources. However, conventional methods to monitor algal physiology use a chlorophyll fluorometer whose use is hampered by high-cost, large footprint, and limited sensitivity for practical samples containing low algal concentration. To overcome these constraints, we developed a multi-level electrode platform for resettable trapping of algae via AC electro-osmosis (ACEO) and negative dielectrophoresis. Preliminary experiments were performed in freshwater with conductivity of 0.02 S/m. Algal trapping was demonstrated at a low voltage of 2 V. The concentration effect was experimentally verified by measuring the fluorescence intensity of algae and using hemocytometer counting chambers at the inlet and outlet of the multilevel microchannel lab-on-a-chip. An optimal frequency was found for trapping, which agrees with the frequency dependence of ACEO flow velocity. Through-flow rate and electrode dimensions were optimized as well. Trapping efficiencies within the range of 26%–65% have been obtained. A maximum trapping rate of 182 cells/s was obtained with a flow rate of 20 μl/min. This lab-on-a-chip shows high potential for improving the limit of detection in algal monitoring and enabling the development of a portable, integrated and automated system for monitoring the quality of source drinking waters. [ABSTRACT FROM AUTHOR]

Graphene is an attractive material for flexible electronics and biosensors, yet its zero bandgap nature has limited the on/off ratio of field-effect transistors (FETs) and the sensitivity of biosensors based on graphene. Graphene nanomesh (GNM), a continuous 2D graphene nanostructure with a high density of holes punched in the basal plane, has been created to introduce lateral confinement and enable improved on/off ratio. However, the GNMs produced to date typically have a relatively large dimension (constriction neck width >5 nm) and low on/off ratio (≈100) limited by the resolution of the lithography process used. Here, the exploration of a directly grown mesoporous silica template is reported for the preparation of ultrafine GNMs with considerably narrower neck width (<3 nm) and strong quantum confinement to enable flexible FETs with greatly improved on/off ratio (up to 1000). With excellent electronic properties and high surface area for the functionalization of specific receptors, it is further shown that the GNM FETs can be readily used to construct highly sensitive biosensors for selective detection of human epidermal growth factor receptor 2, which is further demonstrated for real-time detection of breast cancer cells overexpressed with receptor 2 down to single-cell level. The studies provide a simple and scalable method to GNMs with potential applications for flexible nanoelectronics and biosensors. [ABSTRACT FROM AUTHOR]

The detection and quantification of naturally occurring microbial cellular densities is an essential component of environmental systems monitoring. While there are a number of commonly utilized approaches for monitoring microbial abundance, capacitance-based biosensors represent a promising approach because of their low-cost and label-free detection of microbial cells, but are not as well characterized as more traditional methods. Here, we investigate the applicability of enhanced alternating current electrokinetics (ACEK) capacitive sensing as a new application for rapidly detecting and quantifying microbial cellular densities in cultured and environmentally sourced aquatic samples. ACEK capacitive sensor performance was evaluated using two distinct and dynamic systems – the Great Australian Bight and groundwater from the Oak Ridge Reservation in Oak Ridge, TN. Results demonstrate that ACEK capacitance-based sensing can accurately determine microbial cell counts throughout cellular concentrations typically encountered in naturally occurring microbial communities (10 3 −10 6 cells/mL). A linear relationship was observed between cellular density and capacitance change correlations, allowing a simple linear curve fitting equation to be used for determining microbial abundances in unknown samples. This work provides a foundation for understanding the limits of capacitance-based sensing in natural environmental samples and supports future efforts focusing on evaluating the robustness ACEK capacitance-based within aquatic environments. [ABSTRACT FROM AUTHOR]

Abstract: We review advances in the development and the application of optical biosensing systems based on aptamers. Aptamers exhibit advantages as molecular recognition elements for biosensors when compared to traditional antibodies. Among different detection modes that have been employed, optical methods are among the most used, and the combination of aptamers with novel optical nanomaterials has significantly improved the performance of aptamer-based sensors. The review briefly introduces the unique optical properties of nanoscale materials and the urgency of research on aptamer-conjugated optical nanomaterials in bioanalysis. We then discuss current research activities with typical examples of fluorescence, surface-plasmon resonance and quencher nanomaterials for different detection methods (e.g., fluorescence resonance transfer, colorimetry, and surface-enhanced Raman scattering spectroscopy). The conclusion summarizes this exciting realm of study and offers perspectives for future developments. [Copyright &y& Elsevier]

The influenza epidemic is a huge burden to public health. Current influenza vaccines provide limited protection against new variants due to frequent mutation of the virus. The continual emergence of novel variants necessitates the method rapidly monitoring influenza virus infection in experimental systems. Although several replication-competent reporter viruses carrying fluorescent proteins or small luciferase have been generated in previous studies, visualizing influenza virus infection via such strategy requires reverse genetic modification for each viral strain which is usually time-consuming and inconvenient. Here, we created a novel influenza A nucleoprotein (NP) dependent reporter gene transcription activation module using NP-specific nanobodies. Our results demonstrated the modular design allowed reporter genes (mNeonGreen fluorescent protein and Gaussia luciferase) specifically expressing to detect intracellular NP protein, and therefore acts as a universal biosensor to monitor infection of various influenza A subtypes in living cells. The new system may provide a powerful tool to analyze influenza A infections at the cellular level to facilitate new antiviral drug discovery. Moreover, this approach may easily extend to develop live-cell biosensors for other viruses. [ABSTRACT FROM AUTHOR]

• A low detection limit and high sensitivity for protein biomarkers was achieved. • The micro-cavity at the cantilever is designed for local biological reaction. • The combination of microcantilever biosensor and gold nanoparticle is designed. • The micro-channel and the pH of gold sol was optimized to improve signal amplification effect. • Good detection reproducibility of the biosensor based on gold nanoparticle amplification was obtained. This work reported a microcantilever biosensor based on gold nanoparticles (AuNPs) amplification, which is applied to detect the protein biomarker Alpha fetoprotein (AFP) with high sensitivity. The detection limit of the AuNPs amplified biosensor is 21 pg/mL, about 70 times of magnitude smaller than that without AuNPs amplification. Linear dependence of the relative frequency shift on the AFP concentration between 0 ng/mL and 70 ng/mL were achieved. the sensitivity was dramatically enhanced from 7.68 Hz/nM to 412 Hz/nM by the signal amplification immunoassay, and the good detection reproducibility was obtained. [ABSTRACT FROM AUTHOR]