On‐chip dielectrophoretic recovery and detection of a lactate sensing probiotic from model human saliva

Abstract

Early detection has led to increased survival for multiple cancers; however, the 5year survival rate of oral carcinoma (OC) has remained at 40% for the last several decades. Screening for OC is routinely done via visual examinations, followed by tissue biopsy and laboratory testing. Point-of-care testing would be a more convenient and widely available alternative for at-risk individuals. Increased lactate production is a hallmark of many head-and-neck tumors, due to the Warburg Effect, where tumor cells favor glycolysis in the place of oxidative phosphorylation. To detect excess lactate, we have modified the commensal bacterium Escherichia coli Nissle 1917 to express fluorescent reporter genes in response to extracellular lactate. Administering this commensal as a mouth wash and subsequently collecting saliva for the detection of the reporter may allow for noninvasive, early detection of cancerous lesions in at-risk individuals. Furthermore, we demonstrate a new on-chip electrokinetic technique to recover these probiotic probes from model saliva fluid to improve the detection of reporter gene activation.

Mutation of the peptide-regulated transcription factor ComR for amidated peptide specificity and heterologous function inLactiplantibacillus plantarumWCFS1

“…While bacterial biosensors for markers such as hemin, lactate, hypoxia, and pH have been successfully employed, the ability to reliably detect low-abundance host-derived biomolecules is a far greater genetic engineering challenge and only a small number of successes have been reported. 3–5 Recently, bacteria have been engineered to detect specific sequences of extracellular human DNA through a combination of CRISPR interference and homologous recombination. 6,7 Importantly, this detection scheme could be reprogrammed for a range of sequences.…”

A Paper-Based Fluorescent Sensor for Rapid Early Screening of Oral Squamous Cell Carcinoma

“…Saliva, as the external secretion of the oral cavity, has always been considered as a promising candidate for the early screening of OSCC. − However, there are over 100 different biomarkers with the potential for OSCC diagnosis, representatively including catalase (CAT), interleukin-6 (IL-6), interleukin-8 (IL-8), choline, lactic acid, l -carnitine, miR-24, sialic acid, etc. − How to select the optimized biomarkers for detection becomes a significant issue. Interestingly, lactic acid (byproduct of hypoxic respiration) and choline (closely involved in the synthesis of cell membranes) often have more pronounced concentration differences in saliva samples between OSCC patients and healthy individuals and correlation with disease courses, possessing a significant diagnostic value. − ,− However, since their concentration is quite low, their practical detection always requires us to employ sophisticated and expensive equipment, e.g., high-performance liquid chromatography (HPLC), which further limits their practical applications.…”

Enhancement of dielectrophoresis‐based particle collection from high conducting fluids due to partial electrode insulation

“…One of the challenges of using DEP as a collection method for biologically-derived nanoparticles is the high conductance of biological fluids. The most important highconductivity fluids for liquid biopsy applications include saliva (∼0.45 S/m) [24], blood (∼0.60 S/m) [25,26], plasma (∼1.1 S/m) (Section S1.1), and urine (∼1.87 S/m) [25]. Being able to perform DEP in undiluted blood or plasma is important because it avoids reducing the concentration of rare target nanoparticles.…”