The sustained release of dexamethasone from TiO2 nanotubes reinforced by chitosan to enhance osteoblast function and anti-inflammation activity

Nano-Based Approaches in Surface Modifications of Dental Implants: A Literature Review

Rehabilitation of fully or partially edentulous patients with dental implants represents one of the most frequently used surgical procedures. The work of Branemark, who observed that a piece of titanium embedded in rabbit bone became firmly attached and difficult to remove, introduced the concept of osseointegration and revolutionized modern dentistry. Since then, an ever-growing need for improved implant materials towards enhanced material-tissue integration has emerged. There is a strong belief that nanoscale materials will produce a superior generation of implants with high efficiency, low cost, and high volume. The aim of this review is to explore the contribution of nanomaterials in implantology. A variety of nanomaterials have been proposed as potential candidates for implant surface customization. They can have inherent antibacterial properties, provide enhanced conditions for osseointegration, or act as reservoirs for biomolecules and drugs. Titania nanotubes alone or in combination with biological agents or drugs are used for enhanced tissue integration in dental implants. Regarding immunomodulation and in order to avoid implant rejection, titania nanotubes, graphene, and biopolymers have successfully been utilized, sometimes loaded with anti-inflammatory agents and extracellular vesicles. Peri-implantitis prevention can be achieved through the inherent antibacterial properties of metal nanoparticles and chitosan or hybrid coatings bearing antibiotic substances. For improved corrosion resistance various materials have been explored. However, even though these modifications have shown promising results, future research is necessary to assess their clinical behavior in humans and proceed to widespread commercialization.

Porous surface with fusion peptides embedded in strontium titanate nanotubes elevates osteogenic and antibacterial activity of additively manufactured titanium alloy

It is still a big challenge in orthopedics to treat infected bone defects properly using medical metals. The use of three-dimensional (3D) scaffold materials that simultaneously mimic the skeletal hierarchy and induce sustainable osteogenic and antibacterial functions are a promising solution with an increasing appeal. In this study, we first designed a bifunctional fusion peptide (HHC36-RGD, HR) by linking antimicrobial peptide (HHC36) and arginine-glycine-aspartate (RGD) peptide via 6-aminohexanoic acid. Then the 3D scaffold was fabricated by additive manufacturing, and the strontium titanate nanotube structure (3D-STN) was constructed on its surface. Finally, the HR was anchored to the 3D-STN with the aid of polydopamine (PDA, P), forming the 3D-STN-P-HR scaffold. The results showed that the scaffold exhibited an ordered 3D porous structure, and that the surface was covered by a dense HHC36-RGD layer. Expectedly, the adsorption of PDA effectively slowed down the release of HR. Moreover, the functionalized scaffold had a significant inhibitory effect on Staphylococcus aureus and Escherichia coli, and its antibacterial rate could reach more than 95%. The results of in vitro cell culture experiments demonstrated that the 3D-STN-P-HR scaffold possessed excellent cytocompatibility and could promote the transcription of osteogenic differentiation-related genes and the expression of related proteins. In conclusion, the functionally modified 3D porous titanium alloy scaffold (3D-STN-P-HR) has a balanced antibacterial and osteogenic function, which bodes well for future potential in the customized functional reconstruction of complex-shaped infected bone defects.

Boosting bone cell growth using nanofibrous carboxymethylated cellulose and chitosan on titanium dioxide nanotube array with dual surface charges as a novel multifunctional bioimplant surface

One of the most vital aspects of the orthopedic implant field has been the development of multifunctional coatings that improve bone-implant contact while simultaneously preventing bacterial infection. The present study investigates the fabrication and characterization of multifunctional polysaccharides, including carboxymethyl cellulose (CMCn) and carboxymethyl chitosan nanofibers (CMCHn), as a novel implant coating on titania nanotube arrays (T). Field emission scanning electron microscopy (FESEM) images revealed a nanofibrous morphology with a narrow diameter for CMCn and CMCHn, similar to extracellular matrix nanostructures. Compared to the T surface, the roughness of CMCn and CMCHn samples increased by over 250 %. An improved cell proliferation rate was observed on CMCHn nanofibers with a positively charged surface caused by the amino groups. Furthermore, in an antibacterial experiment, CMCn and CMCHn inhibited bacterial colony formation by 80 % and 73 %, respectively. According to the results, constructed modified CMCn and CMCHn increased osteoblast cell survival while inhibiting bacterial biofilm formation owing to their surface charge and bioinspired physicochemical properties.

Chitosan-based nanoscale systems for doxorubicin delivery: Exploring biomedical application in cancer therapy

Green chemistry has been a growing multidisciplinary field in recent years showing great promise in biomedical applications, especially for cancer therapy. Chitosan (CS) is an abundant biopolymer derived from chitin and is present in insects and fungi. This polysaccharide has favorable characteristics, including biocompatibility, biodegradability, and ease of modification by enzymes and chemicals. CS-based nanoparticles (CS-NPs) have shown potential in the treatment of cancer and other diseases, affording targeted delivery and overcoming drug resistance. The current review emphasizes on the application of CS-NPs for the delivery of a chemotherapeutic agent, doxorubicin (DOX), in cancer therapy as they promote internalization of DOX in cancer cells and prevent the activity of P-glycoprotein (P-gp) to reverse drug resistance. These nanoarchitectures can provide co-delivery of DOX with antitumor agents such as curcumin and cisplatin to induce synergistic cancer therapy. Furthermore, co-loading of DOX with siRNA, shRNA, and miRNA can suppress tumor progression and provide chemosensitivity. Various nanostructures, including lipid-, carbon-, polymeric- and metal-based nanoparticles, are modifiable with CS for DOX delivery, while functionalization of CS-NPs with ligands such as hyaluronic acid promotes selectivity toward tumor cells and prevents DOX resistance. The CS-NPs demonstrate high encapsulation efficiency and due to protonation of amine groups of CS, pH-sensitive release of DOX can occur. Furthermore, redox- and light-responsive CS-NPs have been prepared for DOX delivery in cancer treatment. Leveraging these characteristics and in view of the biocompatibility of CS-NPs, we expect to soon see significant progress towards clinical translation.

Dexamethasone loaded injectable, self-healing hydrogel microspheresbased on UPy-functionalized Gelatin/ZnHAp physical network promotes bone regeneration

Biopolymer-based injectable hydrogels provide great potential as bone tissue engineering (BTE) scaffolds on account of biocompatibility, and pore interconnectivity that enables delivery of cells and/or signaling molecules for bone repair. Recently, Gelatin hydrogels based on H-bonds were considered in response to concerns around the chemical crosslinking agents. In this study, a self-healing gelatin hydrogel with remarkable compressive and self-healing properties was prepared via formation of quadruple hydrogen bonds between ureidopyrimidinon functional groups, which were substituted on NH₂ groups of gelatin(GelUPy). Degree of substitution controls properties of the resulting hydrogel from a shape- memory hydrogel (100% substitution), to a hydrogel (about 80%), to this self-healing hydrogel (about 40%). We report a strategy that adopts an emulsion synthesis approach to delivery of dexamethasone and Ca/Zn ions from injectable self-healing GelUPy hydrogel (GelUPy-ZnHApUPy-DEX), to induce osteogenic differentiation of adipose-derived stem cells, in vitro, and enhance bone regeneration in a cranial bone defect in a rat model. We show that key properties of the composite hydrogels, including mechanical properties, and release behavior of DEX are a match to the requirements of BTE. Overall, our results demonstrate that this self-healing gelatin approach is a promising strategy to enhance bone regeneration through a minimally invasive procedure.

Effect of electrochemical oxidation and drug loading on the antibacterial properties and cell biocompatibility of titanium substrates

A combination of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{ TiO}}_{2}$$\end{document}TiO2 nanotube array (TON) and controlled drug release system is employed to provide enhanced surface properties of titanium implants. Electrochemical anodization process is used to generate TON for introducing, vancomycin, an effective antibacterial drug against Staphylococcusaureus. TON loaded vancomycin is then coated with a number of layers of 10% gelatin using spin coating technique. The gelatin film is reinforced with graphene oxide (GO) nanoparticles to improve the surface bioactivity. The surface of the samples is characterized by field emission electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), and contact angle measurement. The results illustrate that the TON was constructed and vancomycin molecules are successfully loaded. The drug release study shows that the amount of released vancomycin is controlled by the thickness of gelatin layers. With an increase in gelatin film layers from 3 to 7, the release of vancomycin in the burst release phase decreased from 58 to 31%, and sustained release extended from 10 to 17 days. The addition of GO nanoparticles seems to reduce drug release in from 31 to 22% (burst release phase) and prolonged drug release (from 17 to 19 days). MTT assay indicates that samples show no cytotoxicity, and combination of GO nanoparticles with gelatin coating could highly promote MG63 cell proliferation. Soaking the samples in SBF solution after 3 and 7 days demonstrates that hydroxy apatite crystals were deposited on the TON surface with GO-gelatin coating more than surface of TON with gelatin. Moreover, based on the results of disc diffusion assay, both samples (loaded with Vancomycin and coated with gelatin and gelatin-GO) with the inhibition zones equaled to 20 mm show effective antibacterial properties against S. aureus. The evidence demonstrates that titania nanotube loaded with vancomycin and coated with gelatin-GO has a great potential for general applicability to the orthopedic implant field.

N6-methyladenosine reader YTH N6-methyladenosine RNA binding protein 3 or insulin like growth factor 2 mRNA binding protein 2 knockdown protects human bronchial epithelial cells from hypoxia/reoxygenation injury by inactivating p38 MAPK, AKT, ERK1/2, and NF-κB pathways

Lung ischemia/reperfusion (I/R) injury (LIRI) is a common complication after lung transplantation, embolism, and trauma. N6-methyladenosine (m6A) methylation modification is implicated in the pathogenesis of I/R injury. However, there are no or few reports of m6A-related regulators in LIRI till now. In this text, dysregulated genes in lung tissues of LIRI rats versus the sham group were identified by RNA sequencing (RNA-seq). RNA-seq outcomes revealed that only YTH N6-methyladenosine RNA binding protein 3 (YTHDF3) and insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) were differentially expressed in the LIRI versus sham group among 20 m6A-related regulators. Next, the functions and molecular mechanisms of YTHDF3 and IGF2BP2 in LIRI were investigated in a hypoxia/reoxygenation-induced BEAS-2B cell injury model in vitro. Results showed that YTHDF3 or IGF2BP2 knockdown attenuated hypoxia/reoxygenation-mediated inhibitory effects on cell survival and cell cycle progression and inhibited hypoxia/reoxygenation-induced cell apoptosis and pro-inflammatory cytokine secretion in BEAS-2B cells. Genes that could be directly regulated by YTHDF3 or IGF2BP2 were identified based on prior experimental data and bioinformatics analysis. Moreover, multiple potential downstream pathways of YTHDF3 and IGF2BP2 were identified by the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) enrichment analysis of the above-mentioned genes. Among these potential pathways, we demonstrated that YTHDF3 or IGF2BP2 knockdown inhibited hypoxia/reoxygenation-activated p38, ERK1/2, AKT, and NF-κB pathways in BEAS-2B cells. In conclusion, YTHDF3 or IGF2BP2 knockdown weakened hypoxia/reoxygenation-induced human lung bronchial epithelial cell injury by inactivating p38, AKT, ERK1/2, and NF-κB pathways.

Dental Implant Nano-Engineering: Advances, Limitations and Future Directions

Titanium (Ti) and its alloys offer favorable biocompatibility, mechanical properties and corrosion resistance, which makes them an ideal material choice for dental implants. However, the long-term success of Ti-based dental implants may be challenged due to implant-related infections and inadequate osseointegration. With the development of nanotechnology, nanoscale modifications and the application of nanomaterials have become key areas of focus for research on dental implants. Surface modifications and the use of various coatings, as well as the development of the controlled release of antibiotics or proteins, have improved the osseointegration and soft-tissue integration of dental implants, as well as their antibacterial and immunomodulatory functions. This review introduces recent nano-engineering technologies and materials used in topographical modifications and surface coatings of Ti-based dental implants. These advances are discussed and detailed, including an evaluation of the evidence of their biocompatibility, toxicity, antimicrobial activities and in-vivo performances. The comparison between these attempts at nano-engineering reveals that there are still research gaps that must be addressed towards their clinical translation. For instance, customized three-dimensional printing technology and stimuli-responsive, multi-functional and time-programmable implant surfaces holds great promise to advance this field. Furthermore, long-term in vivo studies under physiological conditions are required to ensure the clinical application of nanomaterial-modified dental implants.

Biomedical Implants with Charge-Transfer Monitoring and Regulating Abilities

Transmembrane charge (ion/electron) transfer is essential for maintaining cellular homeostasis and is involved in many biological processes, from protein synthesis to embryonic development in organisms. Designing implant devices that can detect or regulate cellular transmembrane charge transfer is expected to sense and modulate the behaviors of host cells and tissues. Thus, charge transfer can be regarded as a bridge connecting living systems and human-made implantable devices. This review describes the mode and mechanism of charge transfer between organisms and nonliving materials, and summarizes the strategies to endow implants with charge-transfer regulating or monitoring abilities. Furthermore, three major charge-transfer controlling systems, including wired, self-activated, and stimuli-responsive biomedical implants, as well as the design principles and pivotal materials are systematically elaborated. The clinical challenges and the prospects for future development of these implant devices are also discussed.