Volume 33, Issue 4

This review comprises the last decade’s development on experimental techniques for electrochemical and electromechanical sensing of nucleic acids, which originate from pathogenic bacteria, parasites, and viruses commonly found in food, water, and medical context. The electrochemical devices that are of primary interest are those that use voltammetry for detecting DNA and RNA-associated electrochemically active molecules at the working electrode. Attograms of nucleic acids have been reported to be detectable with electrochemical sensors in a batch-mode measurement arrangement. The mass-sensing electromechanical devices sense nucleic acids at the femtogram levels in a flow format without a molecular technique for amplifying target strand using polymerase chain reaction. Both underlying physics and methods of various studies are summarized, with discussion on limitations and potentials. We call attention to the need for sensors that not only detect but also confirm detection, as false negatives are not acceptable when one measures pathogenic species.

The accumulation of misfolded proteins in the form of aggregates characterizes a number of diseases of the central nervous system such as Alzheimer’s disease, Parkinson’s disease, prion diseases, and the diseases of polyglutamine expansion. Recent evidence obtained in vitro and in mice has suggested that protein aggregates are structurally diverse and that their structure largely determines toxicity. The structure of the aggregated proteins in the brain of human patients remains mostly unknown, and we will give here the reasons for which synchrotron-based infrared spectroscopy is emerging as one of the best techniques to access this structure. We will also review the few publications that already exist on the application of synchrotron-based infrared spectroscopy to the study of protein aggregates in human brain. The establishment of a correlation between aggregate structure and neurological toxicity is important not only to understand the aggregation process itself but also in order to specifically target the most toxic structures when searching for prophylactic or therapeutic inhibitors of protein aggregation.

The aim of this work is to review the laser-based analytical techniques for the quantitative determination of uranium in aqueous solutions. Among the various types of laser-based analytical techniques, two different spectroscopic techniques based on the measurement of laser-induced luminescence of hexavalent uranium ions [U(VI)] in groundwater are reviewed in detail. In the first technique, called time-resolved laser fluorescence spectroscopy, the time-resolved laser-induced luminescence intensities of U(VI) as a function of uranium concentration are measured to obtain the calibration curve. In the second technique, which is based on the simultaneous measurement of the U(VI) luminescence and Raman scattering of water, the calibration curve is obtained by measuring the ratio of the luminescence intensity of U(VI) to the Raman scattering intensity of water for the quantitative determination of uranium. A limit of detection of 0.03 μg/l was achieved at an excitation wavelength of 266 nm using these laser spectroscopic techniques. The results determined using these techniques are in good agreement with the results determined by inductively coupled plasma mass spectrometry (ICPMS). Thus, these laser-based analytical techniques will be useful to personnel requiring a rapid determination of uranium before the shipment of samples to an accredited laboratory, where relatively intricate and expensive apparatuses, such as ICPMS and radiochemical spectrometry, are used.

Electrogenerated chemiluminescence (ECL) involves the generation of species at electrode surfaces that then undergo electron-transfer reactions to form excited states that emit light. The ECL method is becoming an increasingly promising method in the life sciences, environmental analysis, and clinical analysis, owing to its good selectivity, high sensitivity, wide dynamic concentration response range, and potential and spatial controllability. Here, we give a mini-review on the advances of the ECL peptide-based bioassay using peptide as the molecular recognition element. First, a general history of ECL development is presented. Then, the general strategies of the ECL peptide-based bioassay are reviewed. Particular attention is paid to the related progress in the last 5 years. Finally, we conclude with the future challenges and prospects in the development of the ECL peptide-based bioassay.