Rapid determination of neomycin in biological samples using fluorescent sensor based on quantum dots with doubly selective binding sites.

A new analytical method was developed to detect neomycin in complex biological samples using molecularly imprinted polymer to construct an optical sensor. Fluorescent neomycin-imprinted polymers (fMIPs) containing both imprinted cavity and boronate affinity site were synthesized on the surface of silica-modified quantum dots. The fMIPs exhibited high selectivity to neomycin by having two binding sites for the target analyte. Neomycin analogues (competing for imprinted cavity) and D-glucose (competing for the boronate affinity site) did not affect the selectivity of the fMIPs. When combined with a fluorescent microplate reader, the obtained fMIP sensor displayed a linear concentration-dependent fluorescence quenching in response to neomycin in the range of 2-1000 µg/L, with a limit of detection as 0.16 µg/L. The fMIP sensor was able to detect trace neomycin in biological samples accurately after simple sample pre-treatment. The sensitivity of the fMIP sensor was higher than HPLC equipped with a fluorescence detector. The fMIP sensor containing the doubly selective binding sites provides a selective, sensitive, accurate, and high through-put approach for neomycin monitoring.

Synthesis of semiconducting polymer microparticles as solid ionophore with abundant complexing sites for long-life Pb(II) sensors.

Intrinsically electrically semiconducting microparticles of semiladder poly(m-phenylenediamine-co-2-hydroxy-5-sulfonic aniline) structures containing abundant functional groups, like -NH-, -N=, -NH2, -OH, -SO3H as complexation sites, were efficiently synthesized by chemical oxidative copolymerization of m-phenylenediamine and 2-hydroxy-5-sulfonic aniline. The obtained copolymers were found to be nonporous spherical microparticles that were able to achieve greater π-conjugated structure, smaller particle aggregate size, and stronger interaction with Pb(II) ions than poly(m-phenylenediamine) containing only -NH-, -N=, and -NH2. A potentiometric Pb(II) sensor was fabricated on the basis of the copolymer microparticles as a crucial solid ionophore component within plasticized PVC. The sensor exhibited a Nernstian response to Pb(II) ions over a wide concentration range, together with a fast response, a wide pH range capability, a long lifetime of up to 5 months, and good selectivity over a wide variety of other ions and redox species. The process for synthesizing the microparticles and fabricating the Pb(II)-sensor can be facilely scaled-up for use in the straightforward long-term online monitoring of Pb(II) ions in heavily polluted wastewaters. This study develops an understanding of the facile synthesis of conducting microparticles bearing many functional groups and their structures governing the potentiometric susceptibility toward interaction between Pb(II) ions and the microparticles for fabricating robust long-lived Pb(II)-sensor, signifying the potential suitability of such novel materials for inexpensive sensitive detection of Pb(II) ions.