Biotinylated ε-Polylysine-Cyclodextrin-Coated Mesoporous Silica Nanoparticles for Targeted pH-Responsive Baicalin Delivery.

Introduction: Baicalin (BAI) is a natural flavonoid with antitumor potential, but its poor water solubility and low bioavailability limit clinical use. Mesoporous silica nanoparticles are promising drug carriers due to their large surface area and tunable pore structure, yet premature drug leakage remains a key challenge. Methods: A multifunctional nanoplatform, designated as BPCD@BAI@BMSN, was constructed to enable efficient baicalin loading, pH-responsive gated release, and biotin-mediated active tumor targeting. A novel biotin-ε-polylysine-cyclodextrin (BPCD) conjugate was synthesized via EDCI/NHS coupling and characterized by NMR and GPC. Hollow mesoporous silica nanoparticles (BMSN) were prepared by the Stöber method, surface-modified with benzothiazole. The BPCD conjugate was coated onto the nanoparticle surface via cyclodextrin-benzothiazole host-guest self-assembly. The resulting nanoparticles were characterized by TEM, DLS, zeta potential, FTIR, and TGA. Drug loading, pH-responsive release, cytotoxicity against SMMC-7721 cells, cellular uptake evaluated by confocal microscopy and flow cytometry, and in vivo antitumor efficacy in nude mice were systematically evaluated. Results: BPCD@BAI@BMSN exhibited near-spherical morphology with a particle size of approximately 200 nm, a positive zeta potential of +10 mV, a drug loading of 19.85%, and an encapsulation efficiency of 89.6%. Cumulative baicalin release reached approximately 62% at pH 5.5, whereas only about 6% was released at pH 7.4, confirming acid-triggered gated release. The blank carrier showed no significant cytotoxicity with cell viability above 95%, while drug-loaded nanoparticles exhibited enhanced cytotoxicity at pH 6.8. Biotin-functionalized nanoparticles demonstrated significantly higher cellular uptake and tumor accumulation compared to non-targeted controls. In vivo, BPCD@BAI@BMSN achieved a tumor growth inhibition rate of 72.5% compared to the control group, with no obvious toxicity to major organs observed during the 21-day treatment period. Conclusion: BPCD@BAI@BMSN integrates high drug loading, pH-responsive supramolecular gating, and active tumor targeting into a single nanoplatform, offering a promising strategy for baicalin delivery with enhanced antitumor efficacy and favorable short-term biosafety.