Chengcheng Feng

Background: Achieving a balance between stable drug loading/delivery and on-demand drug activation/release at the target sites remains a significant challenge for nanomedicines. Carrier-free prodrug nanoassemblies, which rely on the design of prodrug molecules, offer a promising strategy to optimize both drug delivery efficiency and controlled drug release profiles. Methods: A library of doxorubicin (DOX) prodrugs was created by linking DOX to fatty alcohols of varying chain lengths via a tumor-responsive disulfide bond. In vitro studies assessed the stability and drug release kinetics of the nanoassemblies. In vivo studies evaluated their drug delivery efficiency, tumor accumulation, and antitumor activity in mouse models. Results: In vitro results demonstrated that longer fatty alcohol chains improved the stability of the nanoassemblies but slowed down the disassembly and drug release process. DSSC16 NAs (hexadecanol-modified DOX prodrug) significantly prolonged blood circulation time and enhanced tumor accumulation, with AUC values 14.2-fold higher than DiR Sol. In 4T1 tumor-bearing mouse models, DSSC16 NAs exhibited notably stronger antitumor activity, resulting in a final mean tumor volume of 144.39 ± 36.77 mm3, significantly smaller than that of all other groups (p < 0.05 by ANOVA at a 95% confidence interval). Conclusions: These findings underscore the critical role of prodrug molecule design in the development of effective prodrug nanoassemblies. The balance between stability and drug release is pivotal for optimizing drug delivery and maximizing therapeutic efficacy.

Solanum tuberosum lectin (STL) conjugated poly (DL-lactic-co- glycolic acid) (PLGA) nanoparticle (STL-NP) was constructed in this paper as a novel biodegradable nose-to-brain drug delivery system. The in vitro uptake study showed markedly enhanced endocytosis of STL-NP compared to unmodified PLGA nanoparticles (NP) in Calu-3 cells and significant inhibition of uptake in the presence of inhibitor sugar (chitin hydrolysate). Following intranasal administration, coumarin-6 carried by STL-NP was rapidly absorbed into blood and brain. The AUC((0→12 h)) of coumarin-6 in blood, olfactory bulb, cerebrum and cerebellum were about 0.77-, 1.48-, 1.89- and 1.45-fold of those of NP, respectively (p < 0.05). STL-NP demonstrated 1.89-2.45 times (p < 0.01) higher brain targeting efficiency in different brain tissues than unmodified NP. Enhanced accumulation of STL-NP in the brain was also observed by near infrared fluorescence probe image following intranasal administration. The fluorescence signal of STL-NP appeared in olfactory bulb, cerebrum and brainstem early at 0.25 h. The signal in olfactory bulb decreased gradually after 2 h, while the obvious signal in brainstem, cerebrum and cerebellum lasted for more than 8 h. The STL-NP safety experiments showed mild cytotoxicity and negligible cilia irritation. These intriguing in vitro and in vivo results suggest that STL-NP might serve as a promising brain drug delivery system.