The Colorimetric Sensing Strategies Based On Etching Of Gold/Sliver Nanomaterials

Colorimetric sensing method has been widely used in environmental analysis,medical diagnosis and food inspection due to their simple operation,low-cost,and good practicability.A long-term limitation of monocolor changes and low sensitivity in the monocolorimetric sensors seriously restricts its extending application,especially for the traditional organic dyes-based colorimetric sensors.Therefore,the development of more accurate and fast colorimetric methods has become a hot point in current research.Based on this,this paper combined with excellent optical properties of noble metal nanomaterials,we have designed and fabricated gold/sliver nanomaterials etching-based multicolorimetric sensing strategy,and successfully applied to detection of organic small molecules and biological small molecules.This paper mainly has two aspects as following:1.The chromogenic substrates gold nanorods?AuNRs?were synthesized by using seed-mediated growth method.Using the excellent optical properties,and regulating the surface of AuNRs by etching,resulting in a multicolorimetric sensor with high color resolution for detection of inorganic pyrophosphatase?PPase?activity.It operates on the principle that PPase modulates the release of Fe³⁺free from the ferric-pyrophosphate complex(Fe³⁺-PPi)through a specific target-catalyzed hydrolysis process,leading to a better mediation for the unique chemical redox reaction between Fe³⁺and I^-.Subsequently,I^-is oxidized into I₂,which as a moderate oxidant further regulates the surface of AuNRs owing to the rapid etching reaction between I₂ and AuNRs.As a result,the resultant AuNRs surface change further leads to a blue-shift longitudinal LSPR effect of AuNRs,along with a naked-eye-detectable rainbow-like multicolor signal readout.Under optimal conditions,the proposed multicolorimetric sensor exhibits an affordable sensing performance for PPase activity in the range from 1.5 U/L to 9 U/L with a detection limit of 0.8 U/L?S/N=3?.To this point,our strategy not only provides a promising way for breaking the low color resolution limitation of the traditional monocolorimetric sensors,but also broadens the applicability of AuNRs etching-based multicolorimetric sensors.2.The chromogenic substrates silver nanoplates?AgNPRs?were used for colorimetric sensing,the optical properties of AgNPRs were regulated through etching strategy,and resulting in a colorimetric sensor for detection of azobiscarboxamide?ADA?.The principle of sensing relies on the L-Cysteine?L-Cys?could modified to the surface of AgNPRs by Ag-S to protect AgNPRs avoid the iodine anion?I^-?etching,and the special reaction of ADA and L-Cys to modulate the surface chemistry of AgNPRs when added the target ADA.Subsequently,the generated cystine was shed from the surface of AgNPRs,resulting in I^-rapid etching AgNPRs.And the resultant AgNPRs surface change further leads to a blue-shift LSPR effect of AgNPRs,along with the color of the solution changed from the original blue to purple,pink,and yellow signal readout.Based on the above research,the proposed colorimetric sensor exhibits an affordable sensing performance for ADA in the range from 0.5?M to 14?M with a detection limit of 0.23?M?S/N=3?.Furthermore,the colorimetric sensor can be applied for detection of ADA in real flour samples,and is expected to be further applied to point-of-care-testing?POCT?.