Functionalization of breast implants by cyclodextrin in-situ polymerization: a local drug delivery system for augmentation mammaplasty.

Mammaplasty is a widely performed surgical procedure worldwide, utilized for breast reconstruction, in the context of breast cancer treatment, and aesthetic purposes. To enhance post-operative outcomes and reduce risks (hematoma with required evacuation, capsular contracture, implant-associated infection and others), the controlled release of medicaments can be achieved using drug delivery systems based on cyclodextrins (CDs). In this study, our objective was to functionalize commercially available silicone breast implants with smooth and textured surfaces through in-situ polymerization of two CDs: ß-CD/citric acid and 2-hydroxypropyl-ß-CD/citric acid. This functionalization serves as a local drug delivery system for the controlled release of therapeutic molecules that potentially can be a preventive treatment for post-operative complications in mammaplasty interventions. Initially, we evaluated the pre-treatment of sample surfaces with O2 plasma, followed by chitosan grafting. Subsequently, in-situ polymerization using both types of CDs was performed on implants. The results demonstrated that the proposed pre-treatment significantly increased the polymerization yield. The functionalized samples were characterized using microscopic and physicochemical techniques. To evaluate the efficacy of the proposed system for controlled drug delivery in augmentation mammaplasty, three different molecules were utilized: pirfenidone (PFD) for capsular contracture prevention, Rose Bengal (RB) as anticancer agent, and KR-12 peptide (KR-12) to prevent bacterial infection. The release kinetics of PFD, RB, and KR-12 were analyzed using the Korsmeyer-Peppas and monolithic solution mathematical models to identify the respective delivery mechanisms. The antibacterial effect of KR-12 was assessed against Staphylococcus epidermidis and Pseudomonas aeruginosa, revealing that the antibacterial rate of functionalized samples loaded with KR-12 was dependent on the diffusion coefficients. Finally, due to the immunomodulatory properties of KR-12 peptide on epithelial cells, this type of cells was employed to investigate the cytotoxicity of the functionalized samples. These assays confirmed the superior properties of functionalized samples compared to unprotected implants.

Optical biosensors based on semiconductor nanostructures.

The increasing availability of semiconductor-based nanostructures with novel and unique properties has sparked widespread interest in their use in the field of biosensing. The precise control over the size, shape and composition of these nanostructures leads to the accurate control of their physico-chemical properties and overall behavior. Furthermore, modifications can be made to the nanostructures to better suit their integration with biological systems, leading to such interesting properties as enhanced aqueous solubility, biocompatibility or bio-recognition. In the present work, the most significant applications of semiconductor nanostructures in the field of optical biosensing will be reviewed. In particular, the use of quantum dots as fluorescent bioprobes, which is the most widely used application, will be discussed. In addition, the use of some other nanometric structures in the field of biosensing, including porous semiconductors and photonic crystals, will be presented.

Mechanical and in vitro testing of aerosol-gel deposited titania coatings for biocompatible applications.

The biocompatible properties of sol-gel litania have increased the interest in the mechanical properties of this material in the form of functional coatings for prosthetic applications. In the present work. titania coatings with thicknesses of 1 microm have been prepared using the aerosol gel process. The main objective has been to evaluate the mechanical properties of the coatings and to prove their in-vitro biocompatibility. For this purpose, the hardness and Young's modulus of the coatings were measured by nanoindentation with loads in the 6-30 mN range. A continuous increase of these magnitudes was observed for the coatings treated at increasing sintering temperatures (150-800 degrees C). The hardness and the Young's modulus ranged between 15.8-19.5 GPa and 142-186 GPa, respectively. This behaviour has been confirmed by measurements of the plastic energy of deformation in 10 mN full loading unloading tests and by determination of the mean indentation creep under 30 mN loads. The films were additionally characterised by XRD. FTIR and ellipsometry to study the chemical and structural changes produced by sintering. Biocompatibility tests are very conclusive. Cells seeded on aerosol-gel titania coatings grow while adhered onto the surface. These coatings are thus of potential interest for the enhancement of the properties of prosthetic TiAlV alloys.

Textured hydroxyapatite interface onto biomedical titanium-based coatings.

Hydroxyapatite (HAP) bioceramic coatings grown onto titanium-nitride (TiN) buffer layers by the aerosol-gel procedure present interfaces with a preferred growth orientation. These coatings were crystallized at 800 degrees C and subsequently etched to ease the study of the interface by Auger electron spectroscopy depth profiling. Ion beam milling was applied to cross-section samples to analyze the interface structures using transmission electron microscopy. At the interface, the HAP crystals showed a <002> orientation. It was shown by Auger electron spectroscopy depth profiling that O atoms diffuse into the nitride interlayer, indicating that the formation of O channels in the HAP structure is the driving force inducing the textured film. The outstanding biocompatible properties of both the materials and properties of their interface suggest that HAP/TiN structures are particularly well suited for endoprosthetic applications.

Polypropylene glycol is a selective binding inhibitor for LTA and other structurally related TLR2 agonists.

Polypropylene glycol (PPG) is commonly added to bacterial cultures to avoid foaming. However, lipoteichoic acid (LTA) from bacteria grown with PPG lacked cytokine-inducing potency in human blood. We tested the blocking efficacy of several glycols on the cytokine response to staphylococcal LTA in human blood. PPG 1200 was the most potent inhibitor tested, shown for TNF, IL-1beta, IL-6, IL-8, IL-10 and TGF-beta induction, and displayed no cytotoxic effects. TNF induction by Staphylococcus aureus or by Toll-like receptor (TLR)2 agonists (di- and triacylated lipopeptides and LTA) was also inhibited by PPG 1200, but not that induced by Escherichia coli or TLR4 agonists. In flow cytometric studies, PPG-carrying nanobeads bound more rhodamine-labeled LTA than those with glycerol. Additionally, the methyl group peak in the (1)H-NMR of LTA shifted after incubation with increasing PPG 1200 concentrations. Sequential incubation of polystyrene plates with LTA, then PPG 1200 and then blood, with washing steps in between, showed that LTA-induced TNF release was inhibited. But when PPG 1200 was pre-incubated with blood that was washed before LTA was added, TNF induction was not repressed, demonstrating that PPG binds LTA and not cellular structures. In summary, PPG 1200 is a novel inhibitor of cytokine induction by TLR2 agonists, which interferes directly with the ligands.