Hydrogen bond-mediated surface microenvironment regulation of folic acid-functionalized carbon dots for pentoxifylline drug sensing.

As a widely used drug for treating peripheral vascular and ischemic cerebrovascular diseases, the accurate sensing of pentoxifylline (PTX) is crucial for pharmaceutical quality control and therapeutic drug monitoring. In this study, folic acid-functionalized carbon dots (FA-CDs) were synthesized for the "turn-on" fluorescence detection of PTX base on a novel hydrogen bond-mediated surface microenvironment regulation strategy. Upon excitation at 600 nm, the FA-CDs showed maximal fluorescence emission wavelength at 648 nm. The fluorescence of FA-CDs was quenched in aqueous solution with a low quantum yield (QY) of 0.9 %. Upon addition of PTX, the water molecules around FA-CDs were excluded by PTX due to the efficient hydrogen bonds formed between FA-CDs and PTX, resulting in a transition of the surface microenvironment of FA-CDs from water-rich to water-lean state. This change dramatically enhanced the QY of FA-CDs from 0.9 % to 15.85 %. The FA-CDs nanosensor exhibited a fast and selective response to PTX, displaying a good linear range from 0.05 to 1.00 mM and a detection limit of 8.15 μM. Furthermore, the recovery values of this developed method ranged from 95.78 % to 104.06 % in pharmaceuticals, urine and plasma samples, with relative standard deviations ranging from 0.53 % to 4.49 %, indicating this method's high precision and accuracy for PTX detection. This work represents the first example of a fluorescence sensor for PTX detection and provides a promising candidate for practical applications in the field of medicine. The hydrogen bond-mediated surface microenvironment regulation strategy offers an innovative approach for probe design in future.