Fluorescent Imprinted Nanoparticles for Sensing of Chlorogenic Acid in Coffee Extracts

Molecularly imprinted polymers in the analysis of chlorogenic acid: A review

Chlorogenic acid, a phenolic compound, is prevalent across various plant species and has been known for its pharmacological advantages. Health care experts have identified chlorogenic acid as a potential biomarker for treatment of a wide range of illnesses. Therefore, achieving efficient extraction and analysis of chlorogenic acid from plants and their products has become essential. Molecularly imprinted polymers (MIPs) are highly effective adsorbent for the extraction of chlorogenic acid from complex matrices. Currently, there is a lack of comprehensive review article that consolidate the methods utilized for the purification of chlorogenic acid through molecular imprinting. In this context, we have surveyed the common approaches employed in preparing MIPs specifically designed for the analysis of chlorogenic acid, including both conventional and newly developed. This review discusses the advantages, limitations of polymerization techniques and proposed strategies to produce more efficient MIPs for chlorogenic acid enrichment in complex samples. Additionaly, we present advanced imprinting methods for designing MIPs, which improve the adsorption capacity, sensitivity and selectivity towards chlorogenic acid.

An optical fiber chlorogenic acid sensor using a Chitosan membrane coated bent optical fiber probe

Hydrogel polymers have hydrophilic function groups bonded on the polymer's backbone network. Water molecules and compounds soluble in aqueous solution can permeate into hydrogel's network. This property was employed in this work in developing an optical fiber chemical sensor for detecting chlorogenic acid (CGA). A Chitosan membrane was coated on a bent optical fiber probe (BOFP) by simply dipping the BOFP into a Chitosan solution, which was made by dissolving solid Chitosan in a 2 % acetic acid solution, and pulling out. When such a Chitosan-coated BOFP was exposed to CGA in an aqueous sample solution, CGA molecules permeate into the Chitosan membrane, and were detected through monitoring the compound's intrinsic optical absorption signal at 400 nm. Chitosan has one amine group on each of its glucose rings, which helps the membrane concentrating CGA (a weak acid) from aqueous sample solution. Therefore, the sensor shows high sensitivity in detecting CGA with a detection limit of 0.018 μg/mL. The sensor's response to CGA is reversible, because CGA permeation into/out of the polymer network is a reversible process. The effectiveness of the developed sensor for detecting CGA was verified though analyzing CGA in green coffee extract products. The analytical results obtained with the developed sensor agree well with results obtained with a traditional UV/Vis optical absorption spectrometric method. The effectiveness of the sensor for analyzing CGA in green coffee extract samples was also verified through standard addition and recovery experiment with obtained recovery rate ranging from 97 % to 100 %.