In this report, a new cholesterol sensor is developed based on a vertically aligned CNT electrode with two-step electrochemical polymerized enzyme immobilization. Vertically aligned CNTs are selectively grown on a 1 mm2 window of gold coated SiO2/Si substrate by thermal chemical vapor deposition (CVD) with gravity effect and water-assisted etching. CNTs are then simultaneously functionalized and enzyme immobilized by electrochemical polymerization of polyaniline and cholesterol enzymes. Subsequently, ineffective enzymes are removed and new enzymes are electrochemically recharged. Scanning electron microscopic characterization indicates polymer-enzyme nanoparticle coating on CNT surface. Cyclic voltammogram (CV) measurements in cholesterol solution show the oxidation and reduction peaks centered around 450 and −220 mV, respectively. An approximately linear relationship between the cholesterol concentration and the response current could be observed in the concentration range of 50–300 mg/dl with a sensitivity of approximately 0.22 μA/mg·dl−1, which is considerably higher compared to previously reported CNT bioprobe. In addition, good specificity toward glucose, uric acid acetaminophen and ascorbic acid have been obtained. Moreover, sensors have satisfactory stability, repeatability and life time. Therefore, the electropolymerized CNT bioprobe is promising for cholesterol detection in normal cholesterol concentration in human blood.

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In order to increase agricultural productivity, several countries heavily rely on deadly insecticides, known to be toxic to most living organisms and thus significantly affect the food chain. The most obvious impact is to human beings who come into contact, or even consume, pesticide-exposed crops. This work hence focused on an alternative method for insecticide detection at trace concentration under field tests. We proposed a compact Raman spectroscopy system, which consisted of a portable Raman spectroscope, and a surface-enhanced Raman scattering (SERS) substrate, developed for the purpose of such application, on a chip. For the selected portable Raman spectroscope, a laser diode of 785 nm for excitation and a thermoelectric-cooled CCD spectrometer for detection were used. The affordable SERS substrates, with a structure of distributed silver nanorods, were however fabricated by a low-energy magnetron sputtering system. Based on an oblique-angle deposition technique, several deposition parameters, which include a deposition angle, an operating pressure and a substrate rotation, were investigated for their immediate effects on the formation of the nanorods. Trace concentration of organophosphorous chemical agents, including methyl parathion, chlorpyrifos, and malathion, adsorbed on the fabricated SERS substrates were analyzed. The obtained results indicated a sensitive detection for the trace organic analyses of the toxic chemical agents from the purposed portable SERS system.

Abstract-Quartz Crystal Microbalance (QCM) is a special sensor which has acoustic impedance detector by mass loading. In this study Cardiac Troponin T (CTnT) which elevates in all patients with AMI diagnosed by World Heath Organization (WHO) criteria is used as immunoligical assay onto sensor. Detection of the Troponin T is developed based on antigenantibody system on QCM sensor as solid support and signal transduction for immobilization to monitor risk marker of myocardial infarction. To immobilize antibody, the sensor is functionalized with Polyvinyl chloride (PVC) doped COOH by spray coating technique. The modified sensor testing results can be given in short response time and a direct conversion of mass accumulation into a frequency shift representing a measurable electrical signal. The relationship between the Cardiac Troponin T concentration and the response current could be observed in the minimum concentration range at 5 ng/ml.