ABSTRACT
We describe a method for inverting spectroscopic data of the absorption and extinction properties of colloidal samples of resonant particles. We show that, with some prior knowledge, the genetic algorithm employed is able to estimate the probability density function of particle sizes. Since the data are sensitive to the shape and material of the particles, some information about these properties can also be retrieved. The viability of the method is illustrated by inverting numerically generated data, as well as experimental data obtained with specially prepared samples of metallic nanoparticles in aqueous suspension.
ABSTRACT
In the present study, poly(ethylene glycol)-b-poly(N,N-diethylaminoethyl methacrylate) (PEG-b-PDEAEM) amphiphilic block copolymers were synthetized by reversible addition-fragmentation chain transfer (RAFT) polymerization using two different macro chain transfer agents containing PEG of 2000 and 5000 g/mol and varying the length of the PDEAEM segment. From the obtained block copolymers, polymersome type nanometric aggregates were obtained by two different techniques. By direct dispersion, particle diameters around 200 nm were obtained, while by solvent exchange using THF and water, the obtained diameters were around 100 nm. These block copolymers were used to encapsulate gold nanorods and doxorubicin (DOX) with good efficiencies to obtain nanomaterials with potential use as dual stimuli-sensitive drug delivery systems for combined anticancer therapies. Drug delivery studies showed that the release rate of DOX was accelerated when the pH was lowered from 7.4 to 5.8 and also when the systems were irradiated with a NIR laser at pH 7.4. The combination of lower pH and near infrared (NIR) irradiation resulted in higher drug release only in the case of polymersomes with lower molecular weight PEG.
