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Abstract Localized surface plasmons produced by gold and silver nanostructures have been utilized to enhance the intensity of fluorophore molecules. The issue with using nanostructure plasmons for fluorescence enhancement is their short-range nature (5–50 nm from the nanostructures), which limits accessibility to a few molecules. In addition, fluorophore dipoles needed to be aligned with the plasmon electric fields to maximize the fluorescence enhancement. To address these issues, we used low-frequency electric fields (<5 MHz) and commercially available nanorod and nanosphere samples and studied their effectiveness in enhancing the fluorescence of fluorophore-labeled short single-stranded DNA molecules (22 bases). We demonstrated that DNA molecules and nanorod particles can effectively be manipulated around the charging frequency of DNA molecules (∼3 MHz). Nanorod particles enhanced the fluorescence emission rate by ∼50-fold. When the 3 MHz electric field was introduced, the emission rate increased to over 700-fold. We also found that the introduction of a 3 MHz electric field aided the enhancement of the intrinsic quantum yield fluorophore molecules, which resulted in over a 1000-fold fluorescence enhancement. This enhancement was due to the very high electric produced by polarized DNA dipoles at 3 MHz, which resulted in a torque on fluorophore dipoles and subsequently aligning the fluorophore dipole axis with the plasmon electric field. At a fundamental level, our results demonstrate the role of the low-frequency electric field in the fluorophore–plasmon coupling. These findings can directly be applied to many fluorescence detection systems, including the development of biosensors. 

Abstract Dielectrophoresis is a well‐understood phenomenon that has been widely utilized in biomedical applications. Recent advancements in miniaturization have contributed to the development of dielectrophoretic‐based devices for a wide variety of biomedical applications. In particular, the integration of dielectrophoresis with microfluidics, fluorescence, and electrical impedance has produced devices and techniques that are attractive for screening and diagnosing diseases. This review article summarizes the recent utility of dielectrophoresis in assays of biomarker detection. Common screening and diagnostic biomarkers, such as cellular, protein, and nucleic acid, are discussed. Finally, the potential use of recent developments in machine learning approaches toward improving biomarker detection performance is discussed. This review article will be useful for researchers interested in the recent utility of dielectrophoresis in the detection of biomarkers and for those developing new devices to address current gaps in dielectrophoretic biomarker detection. 

Abstract The detection and quantification of nucleic acid and proteomic biomarkers in bodily fluids is a critical part of many medical screening and diagnoses. However, majority of the current detection platforms are not ideal for routine, rapid, and low‐cost testing in point‐of‐care settings. To address this issue, we developed a concept for a disposable universal point‐of‐care biosensor that can detect and quantify nucleic acid and proteomic biomarkers in diluted serum samples. The central tenet of sensing is the use of dielectrophoresis, electrothermal effects, and thermophoresis to selectively and rapidly isolate the biomarkers of interest in electrodes and then quantify using electrical impedance. When the sensor was applied to quantify microRNA and antigen biomarker molecules directly in diluted serum samples, it produced a LOD values in the fM range and sensitivity values from 10¹²to 10¹⁵Ω/M with a 30 min assay time and assay cost of less than $50 per assay. 

Weight loss through dietary and exercise intervention is commonly prescribed but is not effective for all individuals. Recent studies have demonstrated that circulating microRNA (miR) biomarkers could potentially be used to identify individuals who will likely lose weight through diet and exercise and attain a healthy body weight. However, accurate detection of miRs in clinical samples is difficult, error-prone, and expensive. To address this issue, we recently developed iLluminate—a low-cost and highly sensitive miR sensor suitable for point-of-care testing. To investigate if miR testing and iLluminate can be used in real-world obesity applications, we developed a pilot diet and exercise intervention and utilized iLluminate to evaluate miR biomarkers. We evaluated the expression of miRs-140, -935, -let-7b, and -99a, which are biomarkers for fat loss, energy metabolism, and adipogenic differentiation. Responders lost more total mass, tissue mass, and fat mass than non-responders. miRs-140, -935, -let-7b, and -99a, collectively accounted for 6.9% and 8.8% of the explained variability in fat and lean mass, respectively. At the level of the individual coefficients, miRs-140 and -935 were significantly associated with fat loss. Collectively, miRs-140 and -935 provide an additional degree of predictive capability in body mass and fat mass alternations.