A review of the uses of saliva biomarkers, detection methods and requirements for new biomarkers.

An improved one-pot method to synthesize vinyl sulfones from unsaturated systems by using molecular iodine/sodium arenesulfinate/sodium acetate as reagents was described. Vinyl sulfones derived from styrene derivatives were generally obtained in good to excellent yields except for those bearing strong electron releasing substituent. Aliphatic alkenes and activated alkenes gave the corresponding vinyl sulfone products in moderate to good yields. Arylacetylenes yielded the respective β-iodovinyl sulfones in good yields while low yield was observed with aliphatic terminal alkyne. The potentials of the method entail simplicity, short reaction time, non-anhydrous reaction conditions, employing inexpensive, non-metallic reagent and integrating two reactions that are commonly accomplished separately into a single operation. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.

An amperometric micro pH sensor has been developed based on the chemical oxidation of carbon fibre surfaces (diameter of 9 μm and length of ca. 1 mm) to enhance the population of surface quinone groups for the measurement of salivary pH. The pH analysis utilises the electrochemically reversible two-electron, two-proton behaviour of surface quinone groups on the micro-wire electrodes. A Nernstian response is observed across the pH range 2–8 which is the pH range of many biological fluids. We highlight the measurement of pH in small volumes of biological fluids without the need for oxygen removal and specifically the micro pH electrode is examined by measuring the pH of commercial synthetic saliva and authentic human saliva samples. The results correspond well with those obtained by using commercial glass pH electrodes on large volume samples.

Amperometric pH sensing in blood samples has been studied using iridium oxide electrodes. The iridium oxide electrodes are made by electrodeposition of iridium oxide onto an iridium micro-disc electrode from an alkaline solution of iridium(III) oxide. The response of the electrode is studied in aqueous solutions and authentic samples of sheep's blood employing both cyclic voltammetry and square wave voltammetry. Uncertainties of pH measurement in blood samples via cyclic voltammetry (±0.07 pH units) were improved by a factor of two using square wave voltammetry (±0.03 pH units). Limitations of amperometric pH sensing in blood samples are considered as caused by the uncertainty of the required reference measurements (via a conventional glass electrode) and also the use of matrix-free and low ionic strength buffers to calibrate a standard glass electrode for the measurement of blood pH.