Chemo/biosensing Based On Novel Nanosystems Of Monopyridyl Conjugated Polyelectrolytes

Water-soluble conjugated polyelectrolytes?CPEs?,containing?-electron delocalized conjugated backbones and ionic side chains,are of great importance in chemical and biological sensing owing to their outstanding opto-electronical properties and solubility in water.In recent years,conjugated polymer nanoparticles?CPNPs?have also become one of the hotspot in analytical science due to their superior sensing and imaging performance,low cytotoxicity and photostability.Silver nanoparticles have good photochemical properties depending on the size and shape,thus implying that the AgNPs-based nanoprobe can be promising for the design of novel sensors.Therefore,a series of anionic and cationic conjugated polyelectrolytes?P1,P2,P3?bearing pyridyl moiety were synthesized.Moreover,conjugated polyelectrolyte nanoparticles were prepared through modified reprecipitation method and silver-based nanocomposites were fabricated for the characteristic and highly sensitive detection of phytic acid?PA?,persulfate(S₂O₈^2-)and riboflavin?RF?.The main contents of our research include the following three parts:?1?Small-sized?<10 nm?conjugated polyelectrolyte nanoparticles?Pdot-1?were synthesized for the highly sensitive detection of phytic acid using pyridyl-containing conjugated polyelectrolyte P1.The Pdot-1 could bind Fe³⁺,thus leading to the fluorescence quenching of Pdot-1 at 446 nm.In addition,phytic acid with six negatively charged phosphate groups presents strong chelating ability.When phytic acid is added,phytic acid readily binds to Fe³⁺ and the fluorescence of Pdot-1 at 446 nm can be recovered,rendering the highly sensitive and selective sensing of phytic acid.Under the optimum conditions,this facile nanosensor favors the fluorescent determination of phytic acid with the detection limit as low as 10 nM.Furthermore,Pdot-1/Fe³⁺ system can be applied to the assay of phytic acid in cell extracts and the imaging in live cells.?2?The conjugated polyelectrolyte-silver nanoplates?P2-AgNPRs?composite system was designed and synthesized for the high sensitive and selective detection of persulfate ion(S₂O₈^2-).P2,a novel blue-light emitting polymer containing fluorenyl and pyridyl group,can form a complex sensing system with silver nanoplates due to the existence of pyridyl groups in the backbone.With the addition of persulfate ions,the fluorescence of P2-AgNPRs at 402 nm can be significantly quenched owing to the strongly oxidative etch of the triangular silver nanoplatelets by persulfate ions.The fluorescence intensity response exhibited excellent linearity towards the logarithm of S₂O₈^2-in the range of 5.0×10^-6-9.0×10^-5M with the detection limit of 0.9 ?M.Additionally,good selectivity was also obtained,implying a promising perspective for future applications.?3?A novel ratiometric composite system,i.e.,conjugated polyelectrolyte-silver nanoplates?P3-AgNPRs?,was designed and fabricated for the high sensitive and selective detection of riboflavin.The emission peak of P3-AgNPRs?-421 nm?was perfectly coincident with absorbance of riboflavin?-444 nm?.With the addition of riboflavin,the fluorescence of P3-AgNPRs at 421 nm quenched gradually.In the meantime,a new fluorescence peak at 530 nm was observed,hence a novel nanocomposite probe can be constructed for the ratiometric and sensitive detection of riboflavin.The detection limit of this method was as low as 50 nM.The fluorescence intensity I₅₃₀/I₄₂₁ exhibited excellent linearity towards the logarithm of RF in the range of 5.0×10^-8-3.0×10^-6M.