Chitosan and Hydroxyapatite Based Biomaterials to Circumvent Periprosthetic Joint Infections

Every year, worldwide, millions of people suffering from joint pain undergo joint replacement. For most patients, joint arthroplasty reduces pain and improve function, though a small fraction will experience implant failure. One of the main reasons includes prosthetic joint infection (PJI), involving the prosthesis and adjacent tissues. Few microorganisms (MO) are required to inoculate the implant, resulting in the formation of a biofilm on its surface. Standard treatment includes not only removal of the infected prosthesis but also the elimination of necrotic bone fragments, local and/or systemic administration of antibiotics, and revision arthroplasty with a new prosthesis, immediately after the infection is cleared. Therefore, an alternative to the conventional therapeutics would be the incorporation of natural antimicrobial compounds into the prosthesis. Chitosan (Ch) is a potential valuable biomaterial presenting properties such as biocompatibility, biodegradability, low immunogenicity, wound healing ability, antimicrobial activity, and anti-inflammatory potential. Regarding its antimicrobial activity, Gram-negative and Gram-positive bacteria, as well as fungi are highly susceptible to chitosan. Calcium phosphate (CaP)-based materials are commonly utilized in orthopedic and dentistry for their excellent biocompatibility and bioactivity, particularly in the establishment of cohesive bone bonding that yields effective and rapid osteointegration. At present, the majority of CaP-based materials are synthetic, which conducts to the depletion of the natural resources of phosphorous in the future due to the extensive use of phosphate. CaP in the form of hydroxyapatite (HAp) may be extracted from natural sources as fish bones or scales, which are by-products of the fish food industry. Thus, this review aims to enlighten the fundamental characteristics of Ch and HAp biomaterials which makes them attractive to PJI prevention and bone regeneration, summarizing relevant studies with these biomaterials to the field.

Chitosan/Carboxymethyl Cellulose Polyelectrolyte Complex Scaffolds for Pulp Cells Regeneration

Novel polyelectrolyte complex (PEC) chitosan/carboxymethyl cellulose (CMC) scaffolds are prepared using a freeze-dry process. The microstructure is characterized by SEM and the average pore diameters and internal porosities are calculated. The morphology and distribution of pulp cells on these three-dimensional scaffolds are investigated by SEM and confocal laser scanning microscopy (CLSM). The expression of osteonectin (ON) and dentin sialophosphoprotein (DSPP) is detected by reverse transcription polymerase chain reaction (RT-PCR). The scaffolds are then implanted subcutaneously into BALB/c mice. The addition of CMC to chitosan decreases the pore diameter and increases internal porosity. The pulp cells co-cultured in these PEC scaffolds show improved adhesion, spreading, cell capacity, and three-dimensional configurations compared to pure chitosan scaffolds. Based on the data obtained, the chitosan/CMC complex provides an improved scaffold material for pulp tissue engineering.

Preparation and Characterization of Antheraea pernyi Silk Fibroin Based Nanohydroxyapatite Composites

In the present study, Antheraea pernyi silk fibroin (Ap-SF) is employed to regulate the mineralization of hydroxyapatite (HAp) nanocrystals. Calcium phosphate crystals precipitate in the aqueous solution of regenerated Ap-SF at pH 7.4 and room temperature. The samples are charaterized with X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Based on the XRD results, the inorganic phase in the mineralized Ap-SF composites is HAp as small particles with low crystallinity. The FTIR analysis reveals that the HAp crystals are carbonate-substituted HAp and compounded with Ap-SF. The TEM images show mineralized nanofibrils in the composites as rod-like shapes 4—5 nm in diameter. Electron diffraction (SAED) patterns of selected areas of the composites exhibit polycrystalline rings that are ascribed to HAp. SEM images show mineralized Ap-SF composites with several mineralized rods 49—74 nm in diameter.

Biocomposites and hybrid biomaterials based on calcium orthophosphates

The state-of-the-art of biocomposites and hybrid biomaterials based on calcium orthophosphates that are suitable for biomedical applications is presented in this review. Since these types of biomaterials offer many significant and exciting possibilities for hard tissue regeneration, this subject belongs to a rapidly expanding area of biomedical research. Through successful combinations of the desired properties of matrix materials with those of fillers (in such systems, calcium orthophosphates might play either role), innovative bone graft biomaterials can be designed. Various types of biocomposites and hybrid biomaterials based on calcium orthophosphates, either those already in use or being investigated for biomedical applications, are extensively discussed. Many different formulations, in terms of the material constituents, fabrication technologies, structural and bioactive properties as well as both in vitro and in vivo characteristics, have already been proposed. Among the others, the nanostructurally controlled biocomposites, those containing nanodimensional compounds, biomimetically fabricated formulations with collagen, chitin and/or gelatin as well as various functionally graded structures seem to be the most promising candidates for clinical applications. The specific advantages of using biocomposites and hybrid biomaterials based on calcium orthophosphates in the selected applications are highlighted. As the way from the laboratory to the hospital is a long one, and the prospective biomedical candidates have to meet many different necessities, this review also examines the critical issues and scientific challenges that require further research and development.