Biology subjects

Bryan, M. R.

Publications and source records attributed to Bryan, M. R..

4 recordsLinked to original sources

bioRxiv2025

A Dual-Readout Photonic Sensor for Simultaneous Measure-ment of Enzyme Activity and Concentration

Enzyme assays are a cornerstone of basic biology and clinical diagnosis. Typically, enzyme activity is measured, but concentration of the enzyme is also of interest, as are comparisons between concentration and activity. In these situations, separate concentration (i.e. ELISA) and activity (i.e. absorbance) assays are required to fully quantify. Here, we report a multiplex disposable photonic biosensor for simultaneous measurement of enzyme activity and concentration. Capture of the enzyme by a ring resonator-bound antibody produces a red shift in resonance, which can be referenced to a nonspecific binding control. At the same time, enzyme-mediated degradation of a ring-bound substrate produces a resonance blue shift, which can be referenced to a peptide inert to enzymatic cleavage. We tested the dual assay with human Cathepsin-L, dysfunction of which is a hallmark of several diseases, including COVID-19, kidney failure, and cancer. Both assays were found to be well-behaved analytically, with lower limits of detection of 2.0 ng*mL-1 (concentration) and 1.8 ng*mL-1 (activity), well within the range clinically relevant concentrations. Further assessment with a panel of 25 single-donor human serum samples confirmed utility of the assay in a complex, biologically relevant matrix. This approach therefore serves as a useful method for Cathepsin-L detection, and a prototype for other dual-mode photonic enzyme assays.

bioengineering↗

bioRxiv2025

Synergistic MAPT mutations as a platform to uncover modifiers of tau pathogenesis

The natively unfolded tau (MAPT) protein is extremely soluble, which poses challenges when modeling neurofibrillary tangle (NFT) pathology in Alzheimers disease (AD). To overcome this hurdle, we combined P301L and S320F mutations (PL-SF) to generate a rapid and reliable tau pathology platform to expedite the discovery of factors that modify tau aggregation. Using this model, we evaluated heat-shock proteins (Hsp), which have been linked to tau pathology, but whose role in AD remains enigmatic and controversial. In primary neurons, expression of Hsp70, but not Hsc70 or Hsp90, exacerbated tau aggregation. Conversely, lowering Hsp70 or employing a chaperone-deficient tau mutant (PL-SF-4{Delta}) reduced tau phosphorylation and abrogated tau aggregation, highlighting Hsp70 as a key driver of tau aggregation. Hsp70 foci clustered within and surrounding neuritic plaques and NFTs in post-mortem AD brain. Functionally, mature aggregate-bearing neurons showed deficits in neuronal firing and network communication, which were restored by chaperone-binding deficient tau variants that abrogated tau pathology. This study provides a powerful cell-intrinsic model for accelerated tau aggregation, which can be harnessed to identify potent regulators of tau aggregation as promising therapeutic targets.

neuroscience↗

bioRxiv2022

A Photonic Biosensor-Integrated Tissue Chip Platform for Real-Time Sensing of Lung Epithelial Inflammatory Markers

Tissue chip (TC) devices seek to mimic human physiology on a small scale. They are intended to improve upon animal models in terms of reproducibility and human relevance, at a lower monetary and ethical cost. Virtually all TC systems are analyzed at an endpoint, leading to widespread recognition that new methods are needed to enable sensing of specific biomolecules in real time, as they are being produced by the cells. To address this need, we incorporated photonic biosensors for inflammatory cytokines into a model TC. Human bronchial epithelial cells seeded in a microfluidic device were stimulated with lipopolysaccharide, and the cytokines secreted in response sensed in real time. Sensing analyte transport through the TC in response to disruption of tissue barrier was also demonstrated. This work demonstrates the first application of photonic sensors to a human TC device, and will enable new applications in drug development and disease modeling.

bioengineering↗

bioRxiv2020

Array-based analysis of SARS-CoV-2, other coronaviruses, and influenza antibodies in convalescent COVID-19 patients

Detection of antibodies to upper respiratory pathogens is critical to surveillance, assessment of the immune status of individuals, vaccine development, and basic biology. The urgent need for antibody detection tools has proven particularly acute in the COVID-19 era. We report a multiplex label-free antigen microarray on the Arrayed Imaging Reflectometry (AIR) platform for detection of antibodies to SARS-CoV-2, SARS-CoV-1, MERS, three circulating coronavirus strains (HKU1, 229E, OC43) and three strains of influenza. We find that the array is readily able to distinguish uninfected from convalescent COVID-19 subjects, and provides quantitative information about total Ig, as well as IgG- and IgM-specific responses.

immunology↗