Chloramphenicol-imprinted polychitosan bounded with carbon dots as fluorescent sensor, dispersive sorbent, and drug carrier

Chitosan, an abundant natural polysaccharide, was conjugated with carbon dots (CDs) and self-polymerized with chloramphenicol (CAP) templates to synthesize CD-incorporated and molecularly CAP-imprinted polychitosan (CD-MIC). The CD-MIC was used for fluorescent sensing, dispersive sorption, and dosage release of CAP at different pH levels. The sphere of action mechanism, approved by emission and excitation fluorescence, UV–Vis absorption, and fluorescence lifetime measurements, regulated the fluorescence static quenching. By the Perrin model, the quenching extent was linearly correlated to CAP within 0.17 − 33.2 μM (LOD = 37 nM) at pH 7.0. With an imprinting factor of 3.1, the CD-MIC was more selective for CAP than CD, although it was less sensitive to CAP. The recoveries of 5.0 μM CAP from milk matrix were 95% (RSD = 2.3%) for CD-MIC probes and 62% (RSD = 4.5%) for CD. The Langmuir and pseudo-second-order models preferably described the isothermal and kinetic sorptions of CAP into the imprinted cavities in CD-MICs, respectively. The Weber − Morris kinetic model showed three stages involved in intraparticle diffusion, which was pH-dependent and gradually arduous at the later stage, and showed external diffusion partly engaged in the diffusion mechanism. The 20 − 70% of CAP formulated in CAP-embedded CD-MICs were released in 8 − 48 h. The release percentage was lower at pH 7.0 than at pH 5.0 and 9.0, but the equilibrium time was shorter. At pH 7.0, the release percentage reached 45% at 10 min and slowly increased to 51% at 24 h.