Functionalization of Gold Nanostars with Cationic β-Cyclodextrin-Based Polymer for Drug Co-Loading and SERS Monitoring

This article belongs to the Special Issue Cyclodextrins in Drug Delivery.
Gold nanostars (AuNSs) exhibit modulated plasmon resonance and have a high SERS enhancement factor. However, their low colloidal stability limits their biomedical application as a nanomaterial. Cationic β-cyclodextrin-based polymer (CCD/P) has low cytotoxicity, can load and transport drugs more efficiently than the corresponding monomeric form, and has an appropriate cationic group to stabilize gold nanoparticles. In this work, we functionalized AuNSs with CCD/P to load phenylethylamine (PhEA) and piperine (PIP) and evaluated SERS-based applications of the products. PhEA and PIP were included in the polymer and used to functionalize AuNSs, forming a new AuNS-CCD/P-PhEA-PIP nanosystem. The system was characterized by UV–VIS, IR, and NMR spectroscopy, TGA, SPR, DLS, zeta potential analysis, FE-SEM, and TEM. Additionally, Raman optical activity, SERS analysis and complementary theoretical studies were used for characterization. Minor adjustments increased the colloidal stability of AuNSs. The loading capacity of the CCD/P with PhEA-PIP was 95 ± 7%. The physicochemical parameters of the AuNS-CCD/P-PhEA-PIP system, such as size and Z potential, are suitable for potential biomedical applications Raman and SERS studies were used to monitor PhEA and PIP loading and their preferential orientation upon interaction with the surface of AuNSs. This unique nanomaterial could be used for simultaneous drug loading and SERS-based detection.
Orlando Donoso-González was supported by the ANID doctoral scholarship (no. 21180548). Rodrigo Sierpe was supported by the ANID-FONDECYT postdoctoral research grant (no. 3180706). Soledad Bollo, Marcelo Kogan, and Rodrigo Sierpe were funded by ANID-FONDAP (no. 15130011) and ANID-FONDEQUIP EQM (no. 140112). Marcelo Kogan, Rodrigo Sierpe and Orlando Donoso-González were funded by FONDECYT (no. 1170929). The funding was provided by Servicio General de Apoyo a las Investigación (SAI, University of Zaragoza).