An approach for reducing toxicity and enhancing therapeutic potential of supramolecular polyamine phosphate nanoparticles (PANs) through PEGylation of polyamines before their assembly into nanoparticles is presented here. It is shown that the number of polyethylene glycol (PEG) chains for polyamine largely influence physico‐chemical properties of PANs and their biological endpoints. Poly(allylamine hydrochloride) (PAH) are functionalized through carbodiimide chemistry with three ratios of PEG molecules per PAH chain: 0.1, 1, and 10. PEGylated PAH is then assembled into PANs by exposing the polymer to phosphate buffer solution. PANs decrease size and surface charge with increasing PEG ratios as evidenced by dynamic light scattering and zeta potential measurements, with the ten PEG/PAH ratio PANs having practically zero charge. Small angle X‐ray scattering (SAXS) proves that PEG chains form a shell around a polyamine core, which is responsible for the screening of positive charges. MTT experiments show that the screening of amine groups decreases nanoparticle toxicity, with the lowest toxicity for the 10 PEG/PAH ratio. Fluorescence correlation spectroscopy (FCS) proves less interaction with proteins for PEGylated PANs. Positron emission tomography (PET) imaging of 18F labelled PANs shows longer circulation time in healthy mice for PEGylated PANs than non‐PEGylated ones.
Photodynamic
inactivation (PDI) of microorganisms, based on the ability of photosensitizers
to produce reactive oxygen species (ROS) under adequate irradiation,
emerges as a promising technique to face the increasing bacterial
resistance to conventional antimicrobials. In this work, we analyze
the combined action of Riboflavin (Rf) and pectin-coated gold nanoparticles
(PecAuNP) on Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) as suitable PDI strategy. We demonstrate that gold ions can be
generated upon Rf-photosensitized oxidation of PecAuNP. Transient
absorption spectroscopy shows that the Rf cationic radical can accept
an electron from the nanoparticles to yield Au(I) ions, which in aqueous
medium is disproportionate to yield Au0 and Au(III). Microbiological
assays showed that the presence of PecAuNP enhanced the antibacterial
activity of photoirradiated Rf toward S. aureus and P. aeruginosa, in line with the
well-known antibacterial activity of gold ions. Moreover, the irradiation
of Rf solutions containing about 100 μM PecAuNP enabled the
solutions to be bactericidal against both bacteria.
We describe a simple method for the preparation of gold-decorated silica (SiO2) nanoparticles (NPs) by the in situ precipitation method using simple BH4− ions reduction as a procedure, where BH4− ions are adsorbed onto PEI-functionalized SiO2 NPs for stabilizing and reducing gold ions onto PEI-SiO2 surface in water under ambient conditions. The result was 3-nm gold nanoshell NPs attached to SiO2 core (~ 75 nm) with a surface plasmon resonance (SPR) at ~ 680 nm. SPR band is associated with Au NP aggregates that arise from strong interparticle interaction. This is an alternative to the gold-seeding methods and the use of anionic gold species for the obtention of gold-decorated SiO2 NPs with an important red-shift in UV–Vis absorption and with potential applications in biosensors and photothermal therapy.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.