Recent Advances in Lateral Flow Assays for Viral Protein Detection with Nanomaterial-Based Optical Sensors.

Controlling the progression of contagious diseases is crucial for public health management, emphasizing the importance of early viral infection diagnosis. In response, lateral flow assays (LFAs) have been successfully utilized in point-of-care (POC) testing, emerging as a viable alternative to more traditional diagnostic methods. Recent advancements in virus detection have primarily leveraged methods such as reverse transcription-polymerase chain reaction (RT-PCR), reverse transcription-loop-mediated isothermal amplification (RT-LAMP), and the enzyme-linked immunosorbent assay (ELISA). Despite their proven effectiveness, these conventional techniques are often expensive, require specialized expertise, and consume a significant amount of time. In contrast, LFAs utilize nanomaterial-based optical sensing technologies, including colorimetric, fluorescence, and surface-enhanced Raman scattering (SERS), offering quick, straightforward analyses with minimal training and infrastructure requirements for detecting viral proteins in biological samples. This review describes the composition and mechanism of and recent advancements in LFAs for viral protein detection, categorizing them into colorimetric, fluorescent, and SERS-based techniques. Despite significant progress, developing a simple, stable, highly sensitive, and selective LFA system remains a formidable challenge. Nevertheless, an advanced LFA system promises not only to enhance clinical diagnostics but also to extend its utility to environmental monitoring and beyond, demonstrating its potential to revolutionize both healthcare and environmental safety.

One-Pot CRISPR-Cas12a-Based Viral DNA Detection via HRP-Enriched Extended ssDNA-Modified Au@Fe3O4 Nanoparticles.

In the context of virus outbreaks, the need for early and accurate diagnosis has become increasingly urgent. In addition to being crucial for effective disease control, timely and precise detection of viral infections is also necessary for the implementation of essential public health measures, especially during pandemics. Among these measures, point-of-care testing (POCT) stands out as a powerful approach with the potential to revolutionize the landscape of viral diagnosis. In this study, we developed a one-pot clustered regularly interspaced short palindromic repeats (CRISPR)-Cas12a-based viral DNA detection system tailored for POCT; this method utilizes multi-enzyme-modified Au@Fe3O4 nanoparticles. As an alternative to nucleic acid amplification, our method uses single-stranded DNA elongation to facilitate multi-enzyme modification; this guarantees heightened sensitivity and expedites the diagnostic process. We achieved a satisfactory limit of detection of 0.25 nM, demonstrating the remarkable sensitivity of the method without the need for sophisticated equipment. The incorporation of Au@Fe3O4 magnetic nanoparticles facilitates sample separation, further streamlining the workflow and reinforcing the simplicity of our method. This integrated approach offers a practical solution for sensitive viral DNA detection in POCT scenarios, advancing the field of rapid and accurate diagnostics.

Development of a novel microfluidic perfusion 3D cell culture system for improved neuronal cell differentiation.

Three-dimensional (3D) cell cultures have recently gained popularity in the biomedical sciences because of their similarity to the in vivo environment. SH-SY5Y cells, which are neuronal cells and are commonly used to investigate neurodegenerative diseases, have particularly been reported to be differentiated as neuron-like cells expressing neuron-specific markers of mature neurons in static 3D culture environments when compared to static 2D environments, and those in perfusion environments have not yet been investigated. Microfluidic technology has provided perfusion environment which has more similarity to in vivo through mimicking vascular transportation of nutrients, but air bubbles entering into microchannels drastically increase instability of the flow. Furthermore, static incubation commonly used is incompatible with perfusion setup due to its air conditions, which is a critical huddle to the biologists. In the present study, we developed a novel microfluidic perfusion 3D cell culture system that overcomes the disturbance from air bubbles and intuitionally sets the incubation with the perfusion 3D culture. The system is capable of generating concentration gradients between 5 and 95% and air bubble traps were included to increase stability during incubation by collecting air bubbles. To evaluate the perfusion 3D culture, SH-SY5Y differentiation was examined in static 2D, static 3D, and perfusion 3D cultures. Our system supported significantly increased clustering of SH-SY5Y compared to static 2D and 3D methods, as well as increasing neurite growth rate. This novel system therefore supports differentiation of SH-SY5Y and can be used to more accurately model the in vivo environment during cell culture experiments.

Recent Development in Plasmonic Nanobiosensors for Viral DNA/RNA Biomarkers.

Recently, due to the coronavirus pandemic, the need for early diagnosis of infectious diseases, including viruses, is emerging. Though early diagnosis is essential to prevent infection and progression to severe illness, there are few technologies that accurately measure low concentrations of biomarkers. Plasmonic nanomaterials are attracting materials that can effectively amplify various signals, including fluorescence, Raman, and other optical and electromagnetic output. In this review, we introduce recently developed plasmonic nanobiosensors for measuring viral DNA/RNA as potential biomarkers of viral diseases. In addition, we discuss the future perspective of plasmonic nanobiosensors for DNA/RNA detection. This review is expected to help the early diagnosis and pathological interpretation of viruses and other diseases.

Prevention of Microsphere Blockage in Catheter Tubes Using Convex Air Bubbles.

This paper presents a novel method to prevent blockages by embolic microspheres in catheter channels by using convex air bubbles attached to the channels' inner wall surface. The clogging by microspheres can occur by the arching of the microspheres in the catheter. A few studies have been done on reducing the blockage, but their methods are not suitable for use with embolic catheters. In this study, straight catheter channels were fabricated. They had cavities to form convex air bubbles; additionally, a straight channel without the cavities was designed for comparison. Blockage was observed in the straight channel without the cavities, and the blockage arching angle was measured to be 70°, while no blockage occurred in the cavity channel with air bubbles, even at a geometrical arching angle of 85°. The convex air bubbles have an important role in preventing blockages by microspheres. The slip effect on the air bubble surface and the centrifugal effect make the microspheres drift away from the channel wall. It was observed that as the size of the cavity was increased, the drift distance became larger. Additionally, as more convex air bubbles were formed, the amount of early drift to the center increased. It will be advantageous to design a catheter with large cavities that have a small interval between them.

Continuous Preparation of Hollow Polymeric Nanocapsules Using Self-Assembly and a Photo-Crosslinking Process of an Amphiphilic Block Copolymer.

This paper presents a fabrication method of hollow polymeric nanocapsules (HPNCs). The HPNCs were examined to reduce light trapping in an organic light emitting diodes (OLED) device by increasing the refractive index contrast. They were continuously fabricated by the sequential process of self-assembly and photo-crosslinking of an amphiphilic block copolymer of SBR-b-PEGMA, poly(styrene-r-butadiene)-b-poly(poly(ethylene glycol) methyl ether methacrylate) in a flow-focusing microfluidic device. After the photo-crosslinking process, the produced HPNCs have a higher resistance to water and organic solvents, which is applicable to the fabrication process of optical devices. The morphology and hollow structure of the produced nanocapsules were determined by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM). Also, their size control was examined by varying the ratio of inlet flow rates and the morphological difference was studied by changing the polymer concentration. The size was measured by dynamic light scattering (DLS). The refractive index of the layer with and without the HPNCs was measured, and a lower refractive index was obtained in the HPNCs-dispersed layer. In future work, the light extraction efficiency of the HPNCs-dispersed OLED will be examined.