In the present study, new polymer microspheres of amphotericin B (AmB) were prepared by a spray drying technique using cyclodextrin polymers (Poly-CD) to improve the solubility and dissolution of AmB, to prevent in vivo toxic AmB aggregations. Formulations were characterized through scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermal analysis, Raman spectroscopy, particle size, drug purity test and in vitro release studies. The analysis indicated that the chemical structure of AmB remained unchanged in the amorphous solid dispersion, but the structure was changed from crystalline to amorphous. AmB was completely release from such optimized formulations in dissolution media in 40 min. This work may contribute to a new generation of spherical amorphous solid dispersion using a cyclodextrin polymer, which has implications for the possibility of drug development for oral utilization or as powder aerosols for pulmonary administration.

Layer-by-Layer (LbL) films are extensively studied as promising (bio)functional coatings. Although many of their structural features are known, the self-assembly mechanism governing their buildup is still under debate. In this work, we describe the initial buildup and structure of biomimetic LbL films comprised of chondroitin sulfate A (ChS) and poly(L-lysine) (PLL), by means of a Quartz Crystal Microbalance with Dissipation monitoring (QCM-D), Optical Waveguide Lightmode Spectroscopy (OWLS), Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Atomic Force Microscopy (AFM). While the QCM-D and ATR-FTIR reveal a supralinear, so-called “exponential” growth regime, OWLS surprisingly indicates a linear growth regime. Based on a thorough discussion of the experimental data, we conclude from this apparent contradiction that, shortly after the beginning of the buildup, an inner “dense” zone and an outer “diffuse” zone governed by different growth regimes coexist within the film. This observation constitutes an experimental validation of the structural model assuming a dense, gradually restructuring internal zone, proposed in the literature to explain the exponential-to-linear regime transition of exponentially growing LbL films.

Fracture-related infection (FRI) remains a major concern in orthopaedic trauma. Functionalizing implants with antibacterial coatings are a promising strategy in mitigating FRI. Numerous implant coatings have been reported but the preventive and therapeutic effects vary. This systematic review aimed to provide a comprehensive overview of current implant coating strategies to prevent and treat FRI in animal fracture and bone defect models. A literature search was performed in three databases: PubMed, Web of Science and Embase, with predetermined keywords and criteria up to 28 February 2023. Preclinical studies on implant coatings in animal fracture or defect models that assessed antibacterial and bone healing effects were included. A total of 14 studies were included in this systematic review, seven of which used fracture models and seven used defect models. Passive coatings with bacteria adhesion resistance were investigated in two studies. Active coatings with bactericidal effects were investigated in 12 studies, four of which used metal ions including Ag⁺ and Cu²⁺; five studies used antibiotics including chlorhexidine, tigecycline, vancomycin, and gentamicin sulfate; and the other three studies used natural antibacterial materials including chitosan, antimicrobial peptides, and lysostaphin. Overall, these implant coatings exhibited promising efficacy in antibacterial effects and bone formation. Antibacterial coating strategies reduced bacterial infections in animal models and favored bone healing in vivo. Future studies of implant coatings should focus on optimal biocompatibility, antibacterial effects against multi-drug resistant bacteria and polymicrobial infections, and osseointegration and osteogenesis promotion especially in osteoporotic bone by constructing multi-functional coatings for FRI therapy. The clinical treatment of FRI is complex and challenging. This review summarizes novel orthopaedic implant coating strategies applied to FRI in preclinical studies, and offers a perspective on the future development of orthopaedic implant coatings, which can potentially contribute to alternative strategies in clinical practice.