A paper-based point-of-care device for the detection of cysteine using gold nanoparticles from whole blood.

We present a colorimetric probe based on polyvinylpyrrolidone-capped gold nanoparticles (PVP-AuNPs) that is sensitive and selective for cysteine (Cys). A microfluidic paper-based analytical device (µ-PAD) with embedded dried PVP-AuNPs at the polyethersulfone (PES) paper surface is used for Cys detection. When thiol molecules attach to PVP-AuNPs in the presence of Cys, they clump together, and this causes the solution's color to shift from red to blue within 5 minutes. The device is capable of detecting Cys levels between 1.0 µM and 50.0 µM with a limit of detection (LOD) of 0.2 µM under optimized conditions. The stability of the µ-PAD was tested for 100 days, demonstrating re-dispersibility to detect Cys levels in blood. Dried PVP-AuNP-µPADs were integrated with blood plasma separation modules for point-of-care (POC) Cys detection. Consequently, the device shows potential as a self-sustaining, quantification platform with a recovery percentage ranging from 98.44 to 111.9 in clinical samples.

Microfluidics-Based Nanobiosensors for Healthcare Monitoring.

Efficient healthcare management demands prompt decision-making based on fast diagnostics tools, astute data analysis, and informatics analysis. The rapid detection of analytes at the point of care is ensured using microfluidics in synergy with nanotechnology and biotechnology. The nanobiosensors use nanotechnology for testing, rapid disease diagnosis, monitoring, and management. In essence, nanobiosensors detect biomolecules through bioreceptors by modulating the physicochemical signals generating an optical and electrical signal as an outcome of the binding of a biomolecule with the help of a transducer. The nanobiosensors are sensitive and selective and play a significant role in the early identification of diseases. This article reviews the detection method used with the microfluidics platform for nanobiosensors and illustrates the benefits of combining microfluidics and nanobiosensing techniques by various examples. The fundamental aspects, and their application are discussed to illustrate the advancement in the development of microfluidics-based nanobiosensors and the current trends of these nano-sized sensors for point-of-care diagnosis of various diseases and their function in healthcare monitoring.

Bio-inspired self-pumping microfluidic device for cleaning of urea using reduced graphene oxide (rGO) modified polymeric nanohybrid membrane.

In vitro technology facilitates the replication of in vivo tissues more accurately than conventional cell-based artificial organs, enabling researchers to mimic both the structural and functional characteristics of natural systems. Here, we demonstrate a novel spiral-shaped self-pumping microfluidic device for the cleaning of urea by incorporating reduced graphene oxide (rGO) modified a Polyethersulfone (PES) nanohybrid membrane for efficient filtration capacity. The spiral-shaped microfluidic chip is a two-layer configuration of polymethyl methacrylate (PMMA) integrated with the modified filtration membrane. In essence, the device replicates the main features of the kidney (Glomerulus), i.e., a nano-porous membrane modified with reduced graphene oxide to separate the sample fluid from the upper layer and collect the biomolecule-free fluid through the bottom of the device. We have achieved a cleaning efficiency of 97.94 ± 0.6 % using this spiral shaped microfluidic system. The spiral-shaped microfluidic device integrated with nanohybrid membrane has potential for organ-on-a-chips applications.

Optimization and validation of RT-LAMP assay for diagnosis of SARS-CoV2 including the globally dominant Delta variant.

BACKGROUND: Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the causative agent of COVID-19 pandemic, has infected more than 179 million people worldwide. Testing of infected individuals is crucial for identification and isolation, thereby preventing further spread of the disease. Presently, Taqman™ Reverse Transcription Real Time PCR is considered gold standard, and is the most common technique used for molecular testing of COVID-19, though it requires sophisticated equipments, expertise and is also relatively expensive. OBJECTIVE: Development and optimization of an alternate molecular testing method for the diagnosis of COVID-19, through a two step Reverse Transcription Loop-mediated isothermal AMPlification (RT-LAMP). RESULTS: Primers for LAMP were carefully designed for discrimination from other closely related human pathogenic coronaviruses. Care was also taken that primer binding sites are present in conserved regions of SARS-CoV2. Our analysis shows that the primer binding sites are well conserved in all the variants of concern (VOC) and variants of interest (VOI), notified by World Health Organization (WHO). These lineages include B.1.1.7, B.1.351, P.1, B.1.617.2, B.1.427/B.1.429, P.2, B.1.525, P.3, B.1.526 and B.1.617.1. Various DNA polymerases with strand displacement activity were evaluated and conditions were optimized for LAMP amplification and visualization. Different LAMP primer sets were also evaluated using synthetic templates as well as patient samples. CONCLUSION: In a double blind study, the RT-LAMP assay was validated on more than 150 patient samples at two different sites. The RT-LAMP assay appeared to be 89.2% accurate when compared to the Taqman™ rt-RT-PCR assay.

Role of high shear mixing in improving stability and bio-efficacy of botanical oil in water formulation for early stage mosquito eradication.

Neem based formulations conventionally being used as dustable powders, wettable powders, emulsifiable concentrates etc for controlling insects and mosquitoes. These formulations are prepared by mechanical mixing or low shear mixing processes. Among these formulations solvent based EC formulation is more common in use, though it have many drawbacks like phyto-toxicity, flammability, environmental contamination and dermal toxicity. Along with these drawbacks stability of the active ingredient is the most concerned problem, as the active ingredients are unstable in solvent based formulations. Neem oil based oil in water emulsion formulation (EW) formulation may be a safer alternative to EC formulation. In the present study, composition and process technology involved in Neem EW formulations were optimized. Different types of the EW formulation has already been formulated, but no investigations were made to prove the influence of high shear mixing, turbulence flow, time duration on the stability of formulation and its bio-efficacy. The main objective of the study is to determine the effect of turbulence stirring duration on droplet size and emulsion stability. The 60 min turbulence flow mixing at 3600 rpm decreased the particle size from 6.7 to 1.2µm. The prepared formulation stability was further confirmed by different analytical techniques like HPLC and FTIR. The 60 min high shear turbulence stirring enhanced the bio-efficacy in terms of 99 % mortality after 24 h at concentration of 500 ppm of 10 EW.