Natural polyphenols for drug delivery and tissue engineering construction: A review.

Polyphenols, natural compounds rich in phenolic structures, are gaining prominence due to their antioxidant, anti-inflammatory, antibacterial, and anticancer properties, making them valuable in biomedical applications. Through covalent and noncovalent interactions, polyphenols can bind to biomaterials, enhancing their performance and compensating for their shortcomings. Such polyphenol-based biomaterials not only increase the efficacy of polyphenols but also improve drug stability, control release kinetics, and boost the therapeutic effects of drugs. They offer the potential for targeted drug delivery, reducing off-target impacts and enhancing therapeutic outcomes. In tissue engineering, polyphenols promote cell adhesion, proliferation, and differentiation, thus aiding in the formation of functional tissues. Additionally, they offer excellent biocompatibility and mechanical strength, essential in designing scaffolds. This review explores the significant roles of polyphenols in tissue engineering and drug delivery, emphasizing their potential in advancing biomedical research and healthcare.

Preparation of hydrophobic composite membranes based on carboxymethyl cellulose and modified pectin: Effects of grafting a long-chain saturated fatty acid.

In this study, docosanoic acid, a very long chain fatty acid, was used to modify pectin, and the products were incorporated with carboxylmethyl cellulose (CMC) to prepare a hydrophobic composite. Results of structural characterisation showed that docosanoic acid was grafted to pectin through the esterification reaction, and the highest grafting ratio was 7.89 %. After grafting with docosanoic acid, the emulsifying activity and stability of pectin were significantly enhanced from 1.23 × 10-2 and 9.27 % to 4.78 × 10-2 and 26.73 %. Moreover, when modified pectin was blended with CMC instead of native pectin, the hydrophobicity of the composite membranes increased significantly. In detail, the highest contact angle of the composite membrane incorporated with modified pectin was 97.6°, which was much higher than that with native pectin (68.9°). As the grafting ratio of pectin increased, the water vapor permeability of the composite membranes significantly increased, while the water absorption decreased. Furthermore, the mechanical properties and transparency of the composite membranes could be improved by grafting docosanoic acid into pectin. All the results indicated that incorporating docosanoic acid possibly helped improve the comprehensive properties of the composite membranes based on polysaccharides and expand their application in food packaging.

Uncertainty optimization of dental implant based on finite element method, global sensitivity analysis and support vector regression.

In this work, an uncertainty optimization approach for dental implant is proposed to reduce the stress at implant-bone interface. Finite element method is utilized to calculate the stress at implant-bone interface, and support vector regression is used to replace finite element method to ease the computational cost. Deterministic optimization based on support vector regression is conducted, which demonstrates that the method using support vector regression replacing finite element method in dental implant optimization is efficient and reliable. Global sensitivity analysis based on support vector regression is used to assign different uncertainties (manufacturing errors) to different design variables to save the manufacturing cost. Two popular uncertainty optimization methods, k-sigma method and interval method, are used for the uncertainty optimization of dental implant. The results indicate that the stress at implant-bone interface is reduced greatly considering the uncertainties in design variables with the manufacturing cost increasing a little. This approach can be promoted to other types of bio-implants.

Bioinspired anchoring AgNPs onto micro-nanoporous TiO2 orthopedic coatings: Trap-killing of bacteria, surface-regulated osteoblast functions and host responses.

The therapeutic applications of silver nanoparticles (AgNPs) against biomedical device-associated infections (BAI), by local delivery, are encountered with risks of detachment, instability and nanotoxicity in physiological milieus. To firmly anchor AgNPs onto modified biomaterial surfaces through tight physicochemical interactions would potentially relieve these concerns. Herein, we present a strategy for hierarchical TiO2/Ag coating, in an attempt to endow medical titanium (Ti) with anticorrosion and antibacterial properties whilst maintaining normal biological functions. In brief, by harnessing the adhesion and reactivity of bioinspired polydopamine, silver nanoparticles were easily immobilized onto peripheral surface and incorporated into interior cavity of a micro/nanoporous TiO2 ceramic coating in situ grown from template Ti. The resulting coating protected the substrate well from corrosion and gave a sustained release of Ag(+) up to 28 d. An interesting germicidal effect, termed "trap-killing", was observed against Staphylococcus aureus strain. The multiple osteoblast responses, i.e. adherence, spreading, proliferation, and differentiation, were retained normal or promoted, via a putative surface-initiated self-regulation mechanism. After subcutaneous implantation for a month, the coated specimens elicited minimal, comparable inflammatory responses relative to the control. Moreover, this simple and safe functionalization strategy manifested a good degree of flexibility towards three-dimensional sophisticated objects. Expectedly, it can become a prospective bench to bedside solution to current challenges facing orthopedics.

Polydopamine-induced nanocomposite Ag/CaP coatings on the surface of titania nanotubes for antibacterial and osteointegration functions.

The initial implant-associated infections and post aseptic loosening are the major obstacles for the clinical applications of titanium-based dental and orthopedic implants. To tackle these issues, the implant surface is engineered to possess combined osteointegration and antibacterial properties. Therefore, a mussel-inspired novel nano silver/calcium phosphate (CaP) composite coating was prepared on anodized Ti, in the expectation of its surface maintaining preferable biological performance and possessing long-term antibacterial ability. This approach involves three steps: (i) the anodic oxidation of Ti to enable it to have a TiO2 nanotubular (TNT) surface structure, (ii) the self-polymerization of dopamine on TNT and the reduction of Ag and (iii) the modification of the Ag nanoparticles using polydopamine and further being immersed in SBF for the biomimetic mineralization of CaP. The surface morphology and microstructure of this novel coating was fully characterized. The Ag/CaP coatings displayed obvious antibacterial effects to S. aureus bacteria and relatively good in vitro cytocompatibility to MG63 cells. Compared with the pristine Ti, the cells cultured on the coated Ti showed enhanced ALP activities.