Saliva is increasingly recognised as an attractive diagnostic fluid. The presence of various disease signalling salivary biomarkers that accurately reflect normal and disease states in humans and the sampling benefits compared to blood sampling are some of the reasons for this recognition. This explains the burgeoning research field in assay developments and technological advancements for the detection of various salivary biomarkers to improve clinical diagnosis, management, and treatment. This paper reviews the significance of salivary biomarkers for clinical diagnosis and therapeutic applications, with focus on the technologies and biosensing platforms that have been reported for screening these biomarkers.

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A microfluidic chip for electrochemical impedance spectroscopy (EIS) is presented as bio-sensor for label-free detection of proteins by using the example of cardiac troponin I. Troponin I is one of the most specific diagnostic serum biomarkers for myocardial infarction. The microfluidic impedance biosensor chip presented here consists of a microscope glass slide serving as base plate, sputtered electrodes, and a polydimethylsiloxane (PDMS) microchannel. Electrode functionalization protocols were developed considering a possible charge transfer through the sensing layer, in addition to analyte-specific binding by corresponding antibodies and reduction of nonspecific protein adsorption to prevent false-positive signals. Reagents tested for self-assembled monolayers (SAMs) on gold electrodes included thiolated hydrocarbons and thiolated oligonucleotides, where SAMs based on the latter showed a better performance. The corresponding antibody was covalently coupled on the SAM using carbodiimide chemistry. Sampling and measurement took only a few minutes. Application of a human serum albumin (HSA) sample, 1000 ng/mL, led to negligible impedance changes, while application of a troponin I sample, 1 ng/mL, led to a significant shift in the Nyquist plot. The results are promising regarding specific detection of clinically relevant concentrations of biomarkers, such as cardiac markers, with the newly developed microfluidic impedance biosensor chip.

For years, nanotechnology has been considered as an important field that has opened new opportunities for extensive research. In biomedical applications, of all the metal nanoparticles, silver nanoparticles (Ag‐NPs) have played an important role because of their antibacterial properties. Ag‐NPs have been demonstrated to possess antibacterial properties in many applications. However, the minimum number of NPs required on the surface to prevent bacterial growth is yet to be determined. It is worthwhile studying the decrease of bacterial growth rate or the level of inhibition as a function of the size or density of NPs. Therefore, in this paper we discuss the size of the NPs that can stimulate the bactericidal property. It should also be noted that NPs larger than 100 nm might not be effective against bacteria. Moreover, this study employs polyvinyl pyrrolidone (PVP) and cellulose as reductants to form strong covalent bonds under UV light, which can help synthesize Ag‐NP/cotton nanocomposites. This type of nanocomposite displays high cell viability and improved antimicrobial activity. A fairly simple application involves the use of UV light to increase particle distribution and impart bactericidal property.