Reisch, A. | Search bioRxiv

bioRxiv2025

Peptide-functionalized fluorescent polymeric nanoparticles: polysarcosine length defines stealth properties

Stealth properties of nanoparticles are essential for their proper functionalization in biological systems. To address limitations of polyethylene glycol (PEG), commonly used for this purpose, we explore the potential of polysarcosine (PSar) as stealth shell in peptide-functionalized dye-loaded polymeric NPs. To this end, polymeric NPs loaded with rhodamine dye with bulky hydrophobic counterion and bearing azide groups at their surface were grafted with PSar of different lengths ranging from 5 to 19 sarcosine units using strain-promoted cycloaddition. The obtained peptide-functionalized NPs showed remarkable colloidal stability in physiological media. The length of PSar showed a profound effect on stealth properties of NPs. The increase in the length of grafted PSar lead to decrease in the negative surface charge to nearly neutral values and decreased protein adsorption according to fluorescence correlation spectroscopy. The NPs with 19mer PSar showed minimal interactions with live cells and glass surfaces in a complex biological medium, in contrast to its shorter PSar analogues. These stealth NPs bearing HaloTag ligand enabled specific targeting of proteins at the cell surface. The obtained results show that a relatively short PSar peptide can be used for achieving stealth properties in polymeric NPs, allowing specific protein targeting with minimized non-specific interactions. The obtained PSar-functionalized polymeric NPs appear as a powerful platform for the fabrication of the next generation of nanomaterials for bioimaging and biosensing applications.

pharmacology and toxicology↗

bioRxiv2020

Highly fluorescent biodegradable PLGA nano-carriers allows real-time tracking of individual particles in vivo

Poly(lactic-co-glycolic acid) (PLGA)-based drug formulations are approved for the use in humans, however, the potential of PLGA to design nanoparticles (NPs) and target the central nervous system remains to be exploited. The aim of the current study was design PLGA NPs, loading them with bulky fluorophores thereby increasing single particle fluorescence to a level visible by in vivo microscopy, and investigate their brain biodistribution. We developed, highly fluorescent 70 nm PLGA NPs significantly brighter then quantum dots enabling their visualization by intravital real-time 2-photon microscopy. We found that PLGA NPs coated with pluronic F-68 (PF-68) had a substantially longer plasma half-life than uncoated NPs and were taken up by cerebro-vascular endothelial cells. High resolution confocal microscopy revealed that coated PLGA NPs were present in late endothelial endosomes of cerebral vessels within 1 hour after systemic injection and were more readily taken up by endothelial cells in peripheral organs. The current data suggest that PF-68 coated PLGA NPs are taken up by mouse cerebral and peripheral endothelial cells in vivo. The combination of ultra-bright NPs and in vivo imaging may thus represent a promising approach to reduce the gap between development and clinical application of nanoparticle-based drug carriers.

bioengineering↗