The Effect of Postmastectomy Radiation Therapy on Breast Implants: Material Analysis on Silicone and Polyurethane Prosthesis.

INTRODUCTION: The pathogenic mechanism underlying capsular contracture is still unknown. It is certainly a multifactorial process, resulting from human body reaction, biofilm activation, bacteremic seeding, or silicone exposure. The scope of the present article is to investigate the effect of hypofractionated radiotherapy protocol (2.66 Gy × 16 sessions) both on silicone and polyurethane breast implants. METHODS: Silicone implants and polyurethane underwent irradiation according to a hypofractionated radiotherapy protocol for the treatment of breast cancer. After irradiation implant shells underwent mechanical, chemical, and microstructural evaluation by means of tensile testing, infrared spectra in attenuated total reflectance mode, nuclear magnetic resonance, and field emission scanning electron microscopy. RESULTS: At superficial analysis, irradiated silicone samples show several visible secondary and tertiary blebs. Polyurethane implants showed an open cell structure, which closely resembles a sponge. Morphological observation of struts from treated polyurethane sample shows a more compact structure, with significantly shorter and thicker struts compared with untreated sample. The infrared spectra in attenuated total reflectance mode spectra of irradiated and control samples were compared either for silicon and polyurethane samples. In the case of silicone-based membranes, treated and control specimens showed similar bands, with little differences in the treated one. Nuclear magnetic resonance spectra on the fraction soluble in CDCl3 support these observations. Tensile tests on silicone samples showed a softer behavior of the treated ones. Tensile tests on Polyurethane samples showed no significant differences. CONCLUSIONS: Polyurethane implants seem to be more resistant to radiotherapy damage, whereas silicone prosthesis showed more structural, mechanical, and chemical modifications.

Teratogenic effects of environmental concentration of plastic particles on freshwater organisms.

Given the widespread presence of plastics, especially in micro- and nanoscale sizes, in freshwater systems, it is crucial to identify a suitable model organism for assessing the potential toxic and teratogenic effects of exposure to plastic particles. Until now, the early life stage of freshwater organisms and the regeneration capacity in relation to plastic particles exposure is a still poorly investigated topic. In this study, we examine the teratogenic effect on diatom Cocconeis placentula and cnidarian Hydra vulgaris under controlled exposure conditions of poly(styrene-co-methyl methacrylate) (P(S-co-MMA)) particles. Significant effects were observed at the lowest concentrations (0.1 µg/L). A significant increase in the teratological frequency in C. placentula and a significant decrease in the regeneration rate in H. vulgaris were found at the lowest concentration. The delay in hydra regeneration impaired the feeding capacity and tentacles reactivity at 96 h of exposure. No effects on diatom growth were observed upon exposure to P(S-co-MMA) particles (0.1, 1, 100, 10,000 µg/L) for 28 days and these findings agree with other studies investigating algal growth. The application of the Teratogenic Risk Index, modified for diatoms, highlighted a moderate risk for the lowest concentration evaluating C. placentula and low risk at the lowest and the highest concentrations considering H. vulgaris. This study suggests the importance of testing organisms belonging to different trophic levels as diverse teratogenic effects can be found and the need to evaluate environmentally relevant concentrations of plastic particles.

Self-assembled copolymeric nanoparticles as chemically interactive materials for humidity sensors.

Chemical interactive materials (CIM), based on poly(methylmethacrylate-co-bis(benzocyclobutene)) P(MMA-co-BCB) and poly(styrene-co-bis(benzocyclobutene)) P(S-co-BCB) nanoparticles, have been prepared through modified emulsion technique. Experimental conditions, in particular the co-monomer ratio and reaction time, have been tuned to modulate nanoparticles' dimension and optimize their monodispersity. Resistive relative humidity (RH) sensors based on self-assembled copolymeric nanoparticles, cast deposited onto metal interdigitated electrodes (Al, Au, Cr), have been fabricated. The electrical response and the devices' stability have been studied in the range 10-90% RH. Applying 1 V to interdigitated electrodes, a variation of four orders of magnitude, from 10(-12) to 10(-8) A, has been observed and a response time of 130 s has been calculated. Response reproducibility and stability have been tested in subsequent cycles of measurements (working times as long as two days and after six months), confirming the stable performance of the CIMs. Copolymeric nanoparticle assembly has also been studied by quartz microbalance (QMB) devices, where phase shift occurred, by varying RH in the range 10-90%. The CIM coated device shows a sensitivity of about 30 Hz/% (at 10-70% RH), that rapidly increases up to about 2000 Hz/% at 90% RH. The results give evidence for versatile applications of P(MMA-co-BCB) and P(S-co-BCB) nanoparticles for sensing applications.

Functional polymeric nanoparticles for dexamethasone loading and release.

Poly(phenylacetylene) (PPA) and poly(phenylacetylene-co-acrylic acid) (P(PA-co-AA)), nanoparticles bioconjugated with dexamethasone (DXM) during the synthesis, named PPA@DXM and P(PA-co-AA)@DXM, were prepared by a modified surfactant free emulsion method. The loading was studied as a function of different functionality grades of the copolymer and different amounts of drug, obtaining up to 90% of drug loading for P(PA-co-AA)@DXM with 8/1 PA/AA monomer ratio. The SEM images and DLS measurements showed spheres with average diameters in the range 190-500 nm, depending on the content of acrylic acid monomer units in the copolymer and of DXM loading. ζ-potential and surface charge density of DXM loaded nanoparticles were also investigated and confirm the charge density modulation in the range 0.62-2.68σ (µC/m(2)). The results highlight the enhanced capability of our copolymer of hosting DXM, with the advantage of a control of size, surface functionality, charge and release. Moreover we demonstrate for the first time the ability of P(PA-co-AA) DXM loaded nanoparticles to be used in the apoptosis inhibition of human tumor cells (HeLa). On the basis of the results obtained by comparing the effects elicited in HeLa cells by free DXM versus DXM loaded nanoparticles we confirmed the biological efficacy of our preparation.

Optical behavior of conjugated Pt-containing polymetallaynes exposed to gamma-ray radiation doses.

The effect of (60)Co γ irradiation on the absorption and emission spectra of the organometallic polymer [-Pt(PBu(3))(2)-C≡C-C(6)H(4)-C(6)H(4)-C≡C-](n) (Pt-DEBP) in chloroform and toluene solutions for dosimetry applications has been studied. The system Pt-DEBP/chloroform can be used for dosimetric applications in two different ways: (i) monitoring of absorption spectra changes for higher doses (higher than 1 Gy), and (ii) monitoring of emission spectra changes for low doses (below 1 Gy). The response of the polymer solution to γ ray doses has been interpreted with the aid of theoretical studies based on time dependent density functional theory (TD-DFT) calculations on the absorption bands of a model complex and of the possible fragments coming from the degradation of the polymer backbone. It has been proposed that the observed changes are promoted by the attack of radicals, from the radiolysis of the solvent, on the polymer triple bonds.

Nanostructured functional co-polymers bioconjugate integrin inhibitors.

Synthesis and properties of bioconjugates based on functionalized polymeric nanoparticles (PNs) and monoclonal anti-Integrin αV CD51 (aI) antibody were investigated. Polymeric and co-polymeric colloidal nanoparticles with different functionalities, i.e., acid, amine, or thiol, namely poly(methylmethacrylate-co-acrylic acid) [P(MMA-co-AA)], poly(methylmethacrylate-co-dimethylpropargylamine) [P(MMA-co-DMPA)], poly(methylmethacrylate-co-allil mercaptane) [P(MMA-co-AM)], were obtained by tailoring emulsion synthesis and fully characterized by means of spectroscopic techniques and scanning electron microscopy (SEM). Bioconjugates (PN/aI) based on P(MMA) or P(MMA-co-AA) were obtained by loading the polymeric nanoparticles with the antibody anti-Integrin with a simple and straightforward immobilization strategy. Bioconjugates qualitative and quantitative loading analyses were carried out by means of polyacrylamide gel electrophoresis 1D-PAGE, MALDI-TOF, and LC/ESI-MS/MS investigations. The biological efficacy of bioconjugates was confirmed by the reduced migration potential of PN/aI-treated human kidney cells (HEK293). The easy immobilization procedure and high immobilization capacity of polymeric nanoparticles together with tuneable chemical functionalities and dimension of the polymeric nanoparticles open applicative perspectives for targeted delivery.

Organometallic oligomer resolved by radial distribution function of X-ray diffraction analysis.

Platinum-organic oligomers are actively studied for their large physical and functional properties such as solubility, processability, color, luminescence, and optoelectronics related to the different metal groups and auxiliary coligands around the metal coordination spheres. Previous studies on nanotechnology devices have shown that the structural organization of handled metallopolymer generates several 2D or 3D nano-objects, but only based on trans polymorph chains. Here we report the first self-assembly of powder cis-Pt-DEBP oligomers that shows great self-assembling ability to form nanoscale supramolecular architectures. As a powder is obtained that shows a poor crystalline organization of the aggregates, the energy-dispersive X-ray diffraction is the nondestructive technique of choice to obtain short-range order structural parameters of a single nano-object by radial distribution function analysis. The supramolecular architecture of 8-units-long chains reveals a self-assembling organization of 18 chains exhibiting an overall linear inverted open square structure. The ensemble of oligomer chains form a parallelepiped shape with small internal square cavities of approximately 3.2 nm diameter capable of hosting smaller molecules, which opens up to all applications where sieving and sensing is important. This structural investigation of short-range order materials has provided a substantial additional impetus to the field by opening up the area of self-assembled supramolecular materials based on metallopolymers for technological applications.

One-step synthesis of low molecular weight poly(p-phenyleneethynylenevinylene)s via polyaddition of aromatic diynes by catalysis of the [Ru(p-cymene)Cl2]2/AcOH system.

pi-Conjugated low molecular weight polymers characterized by regio- and stereoregular alternation of phenylene and ( E)-1-en-3-yne moieties have been synthesized by polyaddition of 1,4-diethynylbenzene or of 2,5-diethynyl-1,4-alkoxybenzene monomers, employing the commercially available di-micro-chlorobis[( p-cymene)chlororuthenium(II)] complex as the metal catalyst source, under homogeneous, atom-economical, amine- and phosphine-free conditions. Bulk materials of poly( p-phenyleneethynylenevinylene) derivatives are obtained with yields larger than 80%, from which polymers readily soluble in chlorinated solvents and in tetrahydrofuran are extracted in 60-75% yields. The polymers with average degrees of polymerization in the range n AV = 4-8 display optical properties in solution similar to those of the higher molecular weights analogues.

Lipolytic enzymes with improved activity and selectivity upon adsorption on polymeric nanoparticles.

Nanostructured polystyrene (PS) and polymethylmethacrylate (PMMA) were used as carriers for the preparation of bioconjugates with lipolytic enzymes, such as Candida rugosa lipase (CRL) and Pseudomonas cepacia lipase (PCL). Simple addition of the lipase solution to the polymeric nanoparticles under protein-friendly conditions (pH 7.6) led to the formation of polymer-enzyme bioconjugates. Energy filtered-transmission electron microscopy (EF-TEM) performed on immuno-gold labeled samples revealed that the enzyme preferentially binds to the polymer nanoparticles and that the binding does not affect the nanostructured features of the carriers. The studies performed on the activity of the bioconjugates pointed out that the lipases adsorbed onto polymeric nanoparticles show an improved performance in terms of activity and selectivity with respect to those shown by lipases adsorbed on the same non-nanostructured carriers. The residual activities of CRL and PCL immobilized on nanostructured PMMA and PS reached 60% and 74%, respectively. Moreover, we found that enantioselectivity and pH and thermal stability increase upon immobilization. These results highlight the fact that new protein conformers with improved enantioselectivity stabilized after adsorption on nanoparticles are obtained. On the basis of the chemical structures of the selected polymers and the slopes of the adsorption isotherms, a hydrophobic binding model for lipase/nanostructured polymers is suggested.