Cyanuric chloride-modified dendritic SiO2 nanoparticle for switch-on fluorescence monitoring and dispersive solid-phase extraction of isoquinoline alkaloids

The determination of isoquinoline alkaloids (IQAs) is crucial for maximizing the pharmacological benefits of Rhizoma coptidis (RC). In this study, the dendritic silica sphere (dSiO 2 ) was covalently modified with cyanuric chloride (CNCl) to synthesize a porous dNSiO 2 -CNCl NP. The fluorescence of berberine (Ber), palmatine (Pal), coptisine (Cop), and jatrorrhizine (Jat) was remarkably enhanced by dNSiO 2 -CNCl NP for at least 38-fold, inspiring the accurate determination of the isoquinoline total alkaloids (IQTAs) in RC using fluorometry. The method exhibited good linearity within the concentration range of 0.005 to 1 μM, with a limit of detection (LOD) and quantitation (LOQ) of 0.001 and 0.004 μM. Specially, Jat was discovered to form a stable covalent linkage with dNSiO 2 -CNCl, showing an innovative and enduring fluorescent nanoparticle derived from a natural product. Furthermore, using dNSiO 2 -CNCl as a substrate for fluorescence enhancement and a dispersive solid-phase extraction (d-SPE) sorbent, a fluorescence-mediated HPLV-UV method was developed to monitor Ber, Pal, and Cop in serum. Rapid qualitative analysis using fluorescence was initially performed. In chromatography analysis, the linear range for Cop was 0.20 to 10 μM, with LOD and LOQ at 0.035 and 0.110 μM, while Pal and Ber showed good linearity in the range of 0.05 to 10 μM, with LODs and LOQs at 0.013 and 0.040 μM. The spiked recovery rates ranged from 90.4% to 99.8% for the three IQAs, with intra-day precision below 7.9% and inter-day precision below 9.9%. The dual-functional dNSiO 2 -CNCl NP exhibited promising prospect in fluorescence sensing and separation applications for detecting drugs.