Application of a new microcantilever biosensor resonating at the air–liquid interface for direct insulin detection and continuous monitoring of enzymatic reactions

Abstract

Here we describe the application of a recently developed high-resolution microcantilever biosensor resonating at the air-liquid interface for the continuous detection of antigen-antibody and enzymesubstrate interactions. The cantilever at the air-liquid interface demonstrated 50% higher quality factor and a 5.7-fold increase in signal-to-noise-ratio (SNR) compared with one immersed in the purified water. First, a label-free detection of a low molecular weight protein (insulin, 5.8 kDa) in physiological concentration was demonstrated. The liquid facing side of the cantilever was functionalized by coating its surface with insulin antibodies, while the opposite side was exposed to air. The meniscus membrane at the micro-slit around the cantilever sustained the liquid in the microchannel. After optimizing the process of surface functionalization, the resonance frequency shift was successfully measured for insulin solutions of 0.4, 2.0, and 6.3 ng ml 21. To demonstrate additional application of the device for monitoring enzymatic protein degradation, the liquid facing microcantilever surface was coated with human recombinant SOD1 (superoxide dismutase 1) and exposed to various concentrations of proteinase K solution, and the kinetics of the SOD1 digestion was continuously monitored. The results showed that it is a suitable tool for sensitive protein detection and analysis.

Stripping voltammetric detection of insulin at liquid–liquid microinterfaces in the presence of bovine albumin

“…Diabetes mellitus is a metabolic disease associated with either a deficiency in insulin production (type 1 diabetes) or an ineffective use of insulin by the cells (type 2 diabetes). 17 Thus, the determination of insulin is clinically important and an assortment of techniques have been employed for its detection, such as enzyme-linked immunosorbent assays, 18 electrochemical impedance spectroscopy, 19 mass spectrometry, 20 microcantilever biosensors, 21 capillary electrophoresis, 22 and direct oxidative electrochemistry. 23 The large variety of methods investigated for insulin detection is indicative of the on-going need for alternative methods for the detection of insulin which might be amenable to point of care testing.…”

Enhancing detection sensitivity of piezoelectric plate sensor by increasing transverse electromechanical coupling constant

“…In the past two decades, label-free alternatives have been studied by many authors. Some of the examples include quartz crystal microbalance (QCM), 1-3 surface acoustic wave (SAW) devices, 4,5 surface plasmon resonance (SPR), 6,7 silicon microcantilevers, [8][9][10][11] electrochemical sensors, [12][13][14] nanotube and nanowire biosensors. [15][16][17] Although these label-free methods can be rapid and simpler, they generally lack the sensitivity of ELISA.…”

Improving the sensitivity and accuracy of microcantilever biosensors by a truss structure within air medium

“…Microcantilevers (MCLs) are increasingly drawing attention in sensing and actuating applications [1][2][3][4][5]. MCLbased biosensors are one of the basic micromechanical structures, which are free at just one end.…”