A rapid and eco-friendly isothermal amplification microdevice for multiplex detection of foodborne pathogens

In this study, a plastic microdevice based on loop-mediated isothermal amplification (LAMP) was fabricated for the amplification and on-chip fluorescence detection of multiple pathogens. Papers infused with LAMP reagents and specific primers were embedded inside the multiple reaction chambers of the microdevice. A solution containing the target pathogens was injected into the sample chamber, located in the center of the microdevice, and evenly distributed to the reaction chambers simultaneously via centrifugal force. For detection, fisetin, a plant-derived fluorophore, was used as the DNA-intercalating dye. Purified DNAs of Escherichia coli O157:H7 (E. coli O157:H7), Salmonella spp., Staphylococcus aureus (S. aureus), and Cochlodinium polykrikoides were successfully amplified and directly detected on the microdevice, where as low as 0.13 and 0.12 ng μL-1 of the DNA of E. coli O157:H7 and S. aureus, respectively, were identified. In addition, the potential of this microdevice for point-of-care testing was further examined by incorporating on-chip sample purification module and testing using a real sample - milk spiked with Salmonella spp. The thermally lysed milk sample was filtered using polydopamine-coated paper embedded inside a sample chamber and seamlessly transported into the reaction chambers by centrifugal force for subsequent LAMP followed by direct on-chip detection inside the reaction chambers in which fisetin-soaked papers were embedded. The limit of detection for Salmonella spp. was determined to be approximately 1.7 × 102 CFU mL-1 using the microdevice. This microdevice is safe, easy to use, selective, and sensitive enough for point-of-care testing to identify foodborne pathogens as well as environmentally harmful microorganisms.

Emerging Trends in Micro- and Nanoscale Technologies in Medicine: From Basic Discoveries to Translation

We discuss the state of the art and innovative micro- and nanoscale technologies that are finding niches and opening up new opportunities in medicine, particularly in diagnostic and therapeutic applications. We take the design of point-of-care applications and the capture of circulating tumor cells as illustrative examples of the integration of micro- and nanotechnologies into solutions of diagnostic challenges. We describe several novel nanotechnologies that enable imaging cellular structures and molecular events. In therapeutics, we describe the utilization of micro- and nanotechnologies in applications including drug delivery, tissue engineering, and pharmaceutical development/testing. In addition, we discuss relevant challenges that micro- and nanotechnologies face in achieving cost-effective and widespread clinical implementation as well as forecasted applications of micro- and nanotechnologies in medicine.

In situ, dual-mode monitoring of organ-on-a-chip with smartphone-based fluorescence microscope

The use of organ-on-a-chip (OOC) platforms enables improved simulation of the human kidney's response to nephrotoxic drugs. The standard method of analyzing nephrotoxicity from existing OOC has majorly consisted of invasively collecting samples (cells, lysates, media, etc.) from an OOC. Such disruptive analyses potentiate contamination, disrupt the replicated in vivo environment, and require expertize to execute. Moreover, traditional analyses, including immunofluorescence microscopy, immunoblot, and microplate immunoassay are essentially not in situ and require substantial time, resources, and costs. In the present work, the incorporation of fluorescence nanoparticle immunocapture/immunoagglutination assay into an OOC enabled dual-mode monitoring of drug-induced nephrotoxicity in situ. A smartphone-based fluorescence microscope was fabricated as a handheld in situ monitoring device attached to an OOC. Both the presence of γ-glutamyl transpeptidase (GGT) on the apical brush-border membrane of 786-O proximal tubule cells within the OOC surface, and the release of GGT to the outflow of the OOC were evaluated with the fluorescence scatter detection of captured and immunoagglutinated anti-GGT conjugated nanoparticles. This dual-mode assay method provides a novel groundbreaking tool to enable the internal and external in situ monitoring of the OOC, which may be integrated into any existing OOCs to facilitate their subsequent analyses.