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The field of imaging has developed considerably over the past decade and recent advances in the area of nanotechnology, in particular nanomaterials, have opened new opportunities. Polymeric nanoparticles are particularly interesting and a number of novel materials, characterized by stimuli-responsive characteristics and fluorescent tagging, have allowed visualization, intracellular labeling and real-time tracking. In some of the latest applications the nanoparticles have been used for imagining of tumor cells, both in vivo and ex vivo., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

This work reports details pertaining to the formation of chitosan nanoparticles that we prepare by the ionic gelation method. The molecular interactions of the ionic cross-linking of chitosan with tripolyphosphate have been investigated and elucidated by means of all-electron density functional theory. Solvent effects have been taken into account using implicit models. We have identified primary-interaction ionic cross-linking configurations that we define as H-link, T-link, and M-link, and we have quantified the corresponding interaction energies. H-links, which display high interaction energies and are also spatially broadly accessible, are the most probable cross-linking configurations. At close range, proton transfer has been identified, with maximum interaction energies ranging from 12.3 up to 68.3 kcal/mol depending on the protonation of the tripolyphosphate polyanion and the relative coordination of chitosan with tripolyphosphate. On the basis of our results for the linking types (interaction energies and torsion bias), we propose a simple mechanism for their impact on the chitosan/TPP nanoparticle formation process. We introduce the β ratio, which is derived from the commonly used α ratio but is more fundamental since it additionally takes into account structural details of the oligomers.

In the present study chitosan grafted copolymers with poly(ethylene glycol) (CS-g-PEG) were prepared and studied using PEG with molecular weights 2000 and 5000g/mol. The materials were characterized using (1)H NMR, FTIR and WAXD techniques. These polyelectrolytes were ionically crosslinked with tripolyphosphate (TPP) and poly(glutamic acid) (PGA) at different polymer/crosslinking agent ratios (1:1, 2:1, 3:1 and 4:1, w/w) for the nanoencapsulation of bovine serum albumin (BSA). Prepared nanoparticles are spherical in shape with a mean diameter ranging from 150 to 600 nm. The size depends mainly to the molecular weight of the PEG and the crosslinking agent used. The PEG molecular weight also seems to affect the release rate of BSA especially the first burst effect which appears to be high in copolymers containing PEG5000, compared with copolymer prepared with PEG2000, and it is also higher when PGA was used as crosslinking agent, instead of TPP., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Poly(propylene succinate) (PPSu) polymers of average molecular weights from 2,800 to 13,100 g/mol were synthesized and characterized with regard to crystallinity, thermal properties, and cytocompatibility. Higher molecular weight samples exhibited lower degree of crystallinity and melted at lower temperatures. Melting of the polymer appeared to begin at 38 degrees C. PPSu cytocompatibility was investigated based on human umbilical vein endothelial cells viability in the presence of increasing concentrations of polymer, and it was found that PPSu exhibited comparable cytocompatibility with poly(DL-lactide). The feasibility of applying PPSu as a drug carrier was shown for the first time, as solid dispersions and nanoparticles of sodium fluvastatin based in PPSu were prepared. Drug release rates decreased with increasing the molecular weight of PPSu in both solid dispersions and nanoparticles. For dispersions prepared from PPSu of the same molecular weight, drug release rates increased with drug loading. It appears that PPSu applicability as a drug carrier warrants further consideration.

The field of imaging has developed considerably over the past decade and recent advances in the area of nanotechnology, in particular nanomaterials, have opened new opportunities. Polymeric nanoparticles are particularly interesting and a number of novel materials, characterized by stimuli-responsive characteristics and fluorescent tagging, have allowed visualization, intracellular labeling and real-time tracking. In some of the latest applications the nanoparticles have been used for imagining of tumor cells, both in vivo and ex vivo. [ABSTRACT FROM AUTHOR]

Abstract: Poly(propylene succinate-co-caprolactone) copolymers [P(PSu-co-CL)] with different ε-caprolactone (ε-CL) to propylene succcinate (PSu) monomer ratios were synthesized using ring opening polymerization. These polymers consisted of crystalline poly(ε-caprolactone) (PCL) and amorphous poly(propylene succinate) (PPSu) moieties, as shown by WAXD. In vitro biocompatibility studies showed that these copolyesters are biocompatible. Drug-loaded nanoparticles, using tibolone as a model drug, were prepared by the solvent evaporation method. Nanoparticle size ranged between 150 and 190 nm and decreased with increasing propylene succinate (PSu) ratio in the copolymers. Nanoparticle yield, encapsulation efficiency, and drug loading increased with increasing PSu ratio. Scanning Electron Microscopy (SEM) revealed that the prepared nanoparticles had a spherical shape and Transmission Electron Microscopy (TEM) showed that they were self-assembled in core–shell structures. Amorphous PPSu and crystalline PCL comprised the core and shell, respectively. The drug is mainly located into the amorphous core in the form of nanocrystals. Drug release studies showed that complete release of the drug from the nanoparticles occurs over a period of 50 h. The release rate is greatly influenced by the copolymer composition, nanoparticle size, and encapsulation efficiency. Among the main advantages of the nanoparticles produced in this study is the absence of burst effect during drug release. [Copyright &y& Elsevier]

Biocompatible poly(propylene-co-butylene succinate) (PPBSu) copolyesters, containing up to 50 mol% butylene succinate units, were synthesized by the two-stage melt polycondensation method (esterification and polycondensation). The copolymers were fully characterized and biocompatibility studies were also performed. They were proved to be biocompatible and they were used as polymermatrices for the preparation of drug loaded nanoparticles. Nimodipine was selected as a model hydrophobic poorly water soluble drug. From the results obtained by dynamic light scattering (DLS) and scanning electron microscopy (SEM), drug loaded copolymer nanoparticles were found to exhibit a spherical shape and their mean diameter appeared in the range of 180-200 nm. Fourier Transformation-Infrared Spectroscopy (FTIR) spectra indicated that no chemical interaction between the drug and the matrix could be justified, whileWide-Angle X-Ray Diffraction (WAXD) patterns proved a low degree of crystallinity ofNimodipine in the nanoparticles. The release behavior of the model drug from nanoparticles was also investigated in order to identify modifications and find out any possible correlation between the chemical composition of the polymer matrix and the drug release rates. [ABSTRACT FROM AUTHOR]

Abstract: Chitosan (CS) nanoparticles of dorzolamide hydrochloride (Dorzo) and pramipexole hydrochloride (Prami) were prepared by the ionic gelation method and their in vitro properties were studied. The long-term objective is the development of efficient ocular formulations for Dorzo and efficient oral formulations for Prami. The particle size of nanoparticles was affected by the CS/drug ratio whereas it was not affected by the type of drug (Dorzo or Prami). Drug association efficiency to the nanoparticles did not appear to correlate with the drug/CS ratio whereas the loading capacity tended to fall with increasing drug proportion. Based on WAXD data, Dorzo was dispersed in the nanoparticles in crystalline form, probably due to the weak interaction developed between Dorzo and CS/TPP matrix as FT-IR data indicated. In contrast, WAXD and step-scan DSC data indicated that Prami formed a molecular dispersion within the nanoparticles. This was probably due to the potent interactions developed between Prami and CS/TPP matrix, as FT-IR data revealed. The nanoparticles exhibited mucoadhesive properties which diminished with increasing drug content. Sustained in vitro drug release was observed with the Dorzo-loaded CS nanoparticles in PBS (pH 7.4) and with the Prami-loaded CS nanoparticles in simulated intestinal fluid. The results obtained in this study suggest that the Dorzo-loaded CS nanoparticles and the Prami-loaded CS nanoparticles could be further evaluated for the controlled ocular delivery of Dorzo and the controlled oral delivery of Prami, respectively. [Copyright &y& Elsevier]

Wounds continue to be a serious medical concern due to their increasing incidence from injuries, surgery, burns and chronic diseases such as diabetes. Delays in the healing process are influenced by infectious microbes, especially when they are in the biofilm form, which leads to a persistent infection. Biofilms are well known for their increased antibiotic resistance. Therefore, the development of novel wound dressing drug formulations and materials with combined antibacterial, antibiofilm and wound healing properties are required. Nanomaterials (NM) have unique properties due to their size and very large surface area that leads to a wide range of applications. Several NMs have antimicrobial activity combined with wound regeneration features thus give them promising applicability to a variety of wound types. The idea of NM-based antibiotics has been around for a decade at least and there are many recent reviews of the use of nanomaterials as antimicrobials. However, far less attention has been given to exploring if these NMs actually improve wound healing outcomes. In this review, we present an overview of different types of nanomaterials explored specifically for wound healing properties combined with infection control. [ABSTRACT FROM AUTHOR]

Review: [62 refs. [ABSTRACT FROM AUTHOR]