ИСТИНА

One of the most interesting and promising techniques toward direct ultrasensitive detection of various analytes in complex samples is SERS – surface enhanced Raman spectroscopy. SERS-active planar substrates with pure nanostructured silver were prepared by decomposition of an aqueous silver(I) oxide ammonia complex under mild conditions without special reducing agents, salts, stabilizers, or anionic pollutants. These transformations are utilized using thermal decomposition of ultrasonic mist of the complex. The silver complex decomposition occurs in droplets acting as microreactors; the latter also provides constrained growth of AgNPs diminishing their size. During the aerosol deposition procedure, each droplet suffers a thermal shock followed by a decrease of ammonia concentration and partial water evaporation, then followed by decomposition of droplets into films of interlacing silver rings with a highly hierarchic structure of their rims. Despite the key importance of the silver nanostructured layer, it should be coated by a microporous polymer film with thickness of 1−10 μm, which is chemically tuned by acceptor compounds ensuring the generation of bright SERS signals from the targeted previously “invisible” by SERS analytes. Such a newly proposed microporous optically transparent polymer layer acts as a protective coating and, simultaneously, as an effective absorbent of hazardous pollutants – polycyclic aromatic sulfur heterocyclic compounds (PASHs). A novel approach is developed to build up advanced SERS planar sensors with a nanostructured silver layer coated with a thin layer of optically transparent chitosan gel. Modification with appropriate π-acceptor revealed that such a sensor benefits from absorbing and preconcentrating of the analytes, followed by their selective binding into CTCs.