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The COVID-19 pandemic has strained healthcare systems. Sensitive, specific, and timely COVID-19 diagnosis is crucial for effective medical intervention and transmission control. RT-PCR is the most sensitive/specific, but requires costly equipment and trained personnel in centralized laboratories, which are inaccessible to resource-limited areas. Antigen rapid tests enable point-of-care (POC) detection but are significantly less sensitive/specific. CRISPR-Cas systems are compatible with isothermal amplification and dipstick readout, enabling sensitive/specific on-site testing. However, improvements in sensitivity and workflow complexity are needed to spur clinical adoption. We outline the mechanisms/strategies of major CRISPR-Cas systems, evaluate their on-site diagnostic capabilities, and discuss future research directions.

p62/Sequestosome-1 (SQSTM1) is a selective autophagy receptor that recruits and delivers intracellular substrates for bulk clearance through the autophagy lysosomal pathway. Interestingly, p62 also serves as a signaling scaffold to participate in the regulation of multiple physiological processes, including oxidative stress response, metabolism, inflammation, and programmed cell death. Perturbation of p62 activity has been frequently found to be associated with the pathogenesis of many liver diseases. p62 has been identified as a critical component of protein aggregates in the forms of Mallory-Denk bodies (MDBs) or intracellular hyaline bodies (IHBs), which are known to be frequently detected in biopsy samples from alcoholic steatohepatitis (ASH), non-alcoholic steatohepatitis (NASH), and hepatocellular carcinoma (HCC) patients. Importantly, abundance of these p62 inclusion bodies is increasingly recognized as a biomarker for NASH and HCC. Although the level of p62 bodies seems to predict the progression and prognosis of these liver diseases, understanding of the underlying mechanisms by which p62 regulates and contributes to the development and progression of these diseases remains incomplete. In this review, we will focus on the function and regulation of p62, and its pathophysiological roles in the liver, by critically reviewing the findings from preclinical models that recapitulate the pathogenesis and manifestation of these liver diseases in humans. In addition, we will also explore the suitability of p62 as a predictive biomarker and a potential therapeutic target for the treatment of liver diseases, including NASH and HCC, as well as recent development of small-molecule compounds for targeting the p62 signaling axis.

Dengue virus (DENV) and Zika virus (ZIKV) belong to the Flaviviridae family of viruses spread by Aedes aegypti mosquitoes in tropical and subtropical areas. Accurate diagnostic tests to differentiate the 2 infections are necessary for patient management and disease control. Using characterized ZIKV and DENV patient plasma in a blind manner, we validated an ELISA and a rapid immunochromatographic test for ZIKV detection. We engineered the ZIKV nonstructural protein 1 (NS1) for sensitive serologic detection with low cross reactivity against dengue and developed monoclonal antibodies specific for the ZIKV NS1 antigen. As expected, the serologic assays performed better with convalescent than acute plasma samples; the sensitivity ranged from 71% to 88%, depending on the performance of individual tests (IgM/IgG/NS1). Although serologic tests were generally less sensitive with acute samples, our ZIKV NS1 antibodies were able to complement the serologic tests to achieve greater sensitivity for detecting early infections.

Ternary oxide nanosheets are very promising Li-ion battery anode materials. However, they are challenging to synthesize due to their complex compositions. Current ternary oxide nanosheet synthesis strategies are limited and not scalable. Herein, a general methodology is presented for the synthesis of ternary oxide nanosheets with controlled compositions and properties, using graphene oxide as two-dimensional template. TiNb2O7 and Ti0.61Nb1.29O4 have been synthesized as nanosheets for the first time using the graphene oxide-templated method. In addition, NixCo3−xO4 and MnxCo3−xO4 nanosheets have been prepared with tunable compositions. The ternary oxide nanosheets were applied as Li-ion battery anodes with very promising performance.

From a home-based pregnancy self-testing kit, lateral flow assays (LFAs) have proliferated and gained widespread utilization as point-of-care (POC) test kits. Their prevalence is due to their portability, rapid time-to-result, simplicity, stability, and cost-effectiveness. LFAs are well-suited for early detection of infectious diseases, which threatens public health and the economy, enabling timely medical intervention, and management of disease and treatment. This is vital for rural and resource-limited settings where well-equipped laboratories with well-trained personnel are scarce. Nevertheless, LFAs have certain limitations, such as moderate sensitivity and target throughput, as compared to lab-based technologies. Also, the development of LFA, although well-defined, is not straightforward. In this review article, we will elucidate the iterative process of LFA development, and discuss strategies for generating sensitive and specific capture/detector agents, multiplexed detection and signal amplification. An important starting point in LFA development is the clear definition/identification of design inputs and predicate. Newly engineered capture/detector agents, such as nanobodies and aptamers, should possess high binding affinity and functionality in body fluid samples for practical field application. Also, chemical methods, combined with engineering, have enabled multiplexing and signal amplification capabilities for higher target throughput and detection sensitivity. Furthermore, LFAs can be augmented or adapted to other platforms, such as smartphone, spectroscopy and electrochemistry, for quantitative measurements that can engender wider applications and adoption. Through these advances, LFA will transform into a genuinely versatile platform, capable of delivering accurate results that are similar to lab-based technologies, while retaining its advantage as a simple, portable, inexpensive and rapid test.

A versatile and sensitive colorimetric assay that allows the rapid detection of small-molecule targets using the naked eye is demonstrated. The working principle of the assay integrates aptamer-target recognition and the aptamer-controlled growth of gold nanoparticles (Au NPs). Aptamer-target interactions modulate the amount of aptamer strands adsorbed on the surface of aptamer-functionalized Au NPs via desorption of the aptamer strands when target molecules bind with the aptamer. Depending on the resulting aptamer coverage, Au NPs grow into morphologically varied nanostructures, which give rise to different colored solutions. Au NPs with low aptamer coverage grow into spherical NPs, which produce red-colored solutions, whereas Au NPs with high aptamer coverage grow into branched NPs, which produce blue-colored solutions. We achieved visible colorimetric response and nanomolar detection limits for the detection of ochratoxin A (1 nM) in red wine samples, as well as cocaine (1 nM) and 17β-estradiol (0.2 nM) in spiked synthetic urine and saliva, respectively. The detection limits were well within clinically and physiologically relevant ranges, and below the maximum food safety limits. The assay is highly sensitive, specific, and able to detect an array of analytes rapidly without requiring sophisticated equipment, making it relevant for many applications, such as high-throughput drug and clinical screening, food sampling, and diagnostics. Furthermore, the assay is easily adapted as a chip-based platform for rapid and portable target detection.

Circulating microRNAs (miRNAs) are emerging as potential blood-based biomarkers for cancer and other critical diseases. To profile the expression levels of these tiny molecules, especially in a point-of-care setting, it is imperative to quantify them directly in complex biological fluids. Herein, we report the development of a microarray platform with carboxyl-polyethylene glycol (PEG) as a functional layer and aminated hairpin nucleic acid molecules as target-specific capture probes (CPs). Due to the anti-fouling effect conferred by the carboxyl-PEG layer, we could directly detect as little as 10fM of miRNA targets in 20µl of unprocessed human serum. In contrast to the conventional miRNA microarrays, our platform does not require RNA extraction, labeling and target amplification, thus significantly reducing both the sample preparation steps as well as the total assay duration. The use of specially designed hairpin CPs entails reliable discrimination of miRNA sequences with high sequence homology. A nanoparticle-based detection technique, with the help of differential interference contrast (DIC) microscopy, offers excellent resolution down to a single molecule. With the capability of detecting disease-specific miRNA targets directly in human serum, our microarray platform has potential applications in rapid, minimally invasive clinical diagnostic assays.

In this article, we report on direct detection of microRNAs (miRNAs) on a microarray by differential interference contrast (DIC) imaging technique. While the best resolution achieved with a fluorescence scanner is ∼1 μm, the DIC imaging technique adopted in our study offers the possibility of imaging individual reporting gold nanoparticles, or, in other words, individual miRNA strands. Due to its unrivalled resolution, the present technique could detect as low as 300 copies of target miRNAs in a sample volume of 1.0 μl. With the greatly improved sensitivity, the amount of total RNA needed in the assay is reduced to only a few nanograms, offering an excellent opportunity for fast and direct miRNA profiling without engaging any labeling and amplification procedure. Expression patterns of hsa-let-7 family members in healthy versus cancer cells analyzed on our microarray, are found to be consistent with the patterns obtained on a commercial microarray and those reported in the literature.