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Colorimetric readout for the detection of infectious diseases is gaining traction at the point of care/need owing to its ease of analysis and interpretation, and integration potential with highly specific loop-mediated amplification (LAMP) assays. However, coupling colorimetric readout with LAMP is rife with challenges including, rapidity, inter-user variability, colorimetric signal quantification, and user involvement in sequential steps of the LAMP assay, hindering its application. To address these challenges, for the first time, we propose a remotely smartphone-operated automated setup consisting of (i) an additively manufactured microfluidic cartridge, (ii) a portable reflected-light imaging setup with controlled epi-illumination (PRICE) module, and (iii) a control and data analysis module. The microfluidic cartridge facilitates sample collection, lysis, mixing of amplification reagents stored on-chip, and subsequent isothermal heating for initiation of amplification in a novel way by employing tunable elastomeric chambers and auxiliary components (heaters and linear actuators). PRICE offers a new imaging setup that captures the colorimetric change of the amplification media over a plasmonic nanostructured substrate in a controlled and noise-free environment for rapid minute-scale nucleic acid detection. The control and data analysis module employs microprocessors to automate cartridge operation in tandem with the imaging module. The different device components were characterized individually and finally, as a proof of concept, SARS-CoV-2 wild-type RNA was detected with a turnaround time of 13 minutes, showing the device's clinical feasibility. The suggested automated device can be adopted in future iterations for other detection and molecular assays that require sequential fluid handling steps. [ABSTRACT FROM AUTHOR]

Cancer cells shed into biofluids extracellular vesicles (EVs) — nanoscale membrane particles carrying diagnostic information. EVs shed by heterogeneous populations of tumor cells offer a unique opportunity to access biologically important aspects of disease complexity. Glioblastoma (GBM) exemplifies cancers that are incurable, because their temporal dynamics and molecular complexity evade standard diagnostic methods and confound therapeutic efforts. Liquid biopsy based on EVs offers unprecedented real-time access to complex tumour signatures, but it is not used clinically due to inefficient testing methods. We report on a nanostructured microfluidic-device that employs SERS for unambiguous identification of EVs from different GBM cell populations. The device features fabless plasmonic nanobowties for label-free and non-immunological SERS detection of EVs. This nanobowtiefluidic device combines the advanced characteristics of plasmonic nanobowties with a high throughput sample-delivery system for concentration of the analytes in the vicinity of the detection site. We showed theoretically and experimentally that the fluidic device assists the monolayer distribution of the EVs, which dramatically increase the probability of EV's existence in the laser illumination area. In addition, the optimized fabless nanobowtie structures with an average electric field enhancement factor of 9 × 105 achieve distinguishable and high intensity SERS signals. Using the nanobowtiefluidic and micro-Raman equipment, we were able to distinguish a library of peaks expressed in GBM EV subpopulations from two distinct glioblastoma cell lines (U373, U87) and compare them to those of non-cancerous glial EVs (NHA) and artificial homogenous vesicles (e.g. DOPC/Chol). This cost-effective and easy-to-fabricate SERS platform and a portable sample-delivery system for discerning the sub-population of GBM EVs and non-cancerous glial EVs may have broader applications to different types of cancer cells and their molecular/oncogenic signature. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide (H2O2) is an essential molecule to various physiological processes and is commonly used for the detection and monitoring of glucose and cell viability.  Furthermore, it is identified as a signal of oncogenic growth due to its widespread presence within the cancer cell environment. However, the low concentrations of H2O2 released by cancer cells' metabolism challenge current detection methods' capabilities and their practicality for translation to clinical applications. Colorimetric assays with simple readouts are a promising solution, provided that their sensitivity and rapidity in detecting H2O2 improve.  Here, a plasmonic enhanced nanopatterned platform is proposed coupled with an Amplex Red assay to monitor the color change of H2O2 released from cancer cells. The nanopatterned platform embedded into a multiplexed microfluidic device enhances the kinetics of the reaction ≈7 times. This approach has reached a limit of detection of 1 pm when tested in breast (MCF‐7) and prostate (PC‐3) cancer media. The collected color images are processed and analyzed by a machine learning algorithm that categorizes them into “high” or “low‐to‐no” concentrations of H2O2 with 91% accuracy. This study is a step toward developing a device for highly sensitive H2O2 detection that is easily adaptable, user‐friendly, portable, and automated. [ABSTRACT FROM AUTHOR]

We present a nanofilter based on pillar-assisted self-assembly microparticles for efficient capture of bacteria. Under an optimized condition, we simply fill the arrays of microscale pillars with submicron scale polystyrene particles to create a filter with nanoscale pore diameter in the range of 308 nm. The design parameters such as the pillar diameter and the inter-pillar spacing in the range of 5 μm-40 μm are optimized using a multi-physics finite element analysis and computational study based on bi-directionally coupled laminar flow and particle tracking solvers. The underlying dynamics of microparticles accumulation in the pillar array region are thoroughly investigated by studying the pillar wall shear stress and the filter pore diameter. The impact of design parameters on the device characteristics such as microparticles entrapment efficiency, pressure drop, and inter-pillar flow velocity is studied. We confirm a bell-curve trend in the capture efficiency versus inter-pillar spacing. Accordingly, the 10 μm inter-pillar spacing offers the highest capture capability (58.8%), with a decreasing entrapping trend for devices with larger inter-pillar spacing. This is the case that the 5 μm inter-pillar spacing demonstrates the highest pillar wall shear stress limiting its entrapping efficiency. As a proof of concept, fluorescently labeled Escherichia coli bacteria (E. coli) were captured using the proposed device. This device provides a simple design, robust operation, and ease of use. All of which are essential attributes for point of care devices. [ABSTRACT FROM AUTHOR]