Novel anti-infective activities of chitosan immobilized titanium surface with enhanced osteogenic properties

Dual-Functional Polyetheretherketone Surface with an Enhanced Osteogenic Capability and an Antibacterial Adhesion Property In Vitro by Chitosan Modification

A chitosan layer was covalently bonded to a polyetheretherketone (PEEK) surface using a simple facile self-assembly method to address inadequate biological activity and infection around the implant. The surface characterization, layer degradation, biological activity, and antibacterial adhesion properties of chitosan-modified PEEK (PEEK-CS) were studied. Through chitosan grafting, the surface morphology changed, the surface roughness increased, and the contact angle decreased significantly. PEEK-CS boosted cell adhesion, proliferation, increased alkaline phosphate activity, extracellular matrix mineralization, and expression of osteogenic genes. PEEK-CS demonstrated less adhesion to Porphyromonas gingivalis as well as less bacterial adhesion to P. gingivalis and Streptococcus mutans. According to our findings, chitosan modification significantly improved the osteogenic ability and antibacterial adhesion of PEEK in vitro.

Influence of surface electric charge of Ti implants on osteoblastic interaction: A systematic review

Objective

A critical analysis of the existing literature to answer “What is the influence of electrical charge of titanium alloys in the electrical interaction with osteoblastic cells for osseointegration?”.

Design

This systematic review followed PRISMA. The personalized search strategy was applied in PubMed, Science Direct, Embase, and Scopus databases, furthermore, in the grey literature in the Google Scholar and ProQuest. The selection process was carried out in two stages independently by two reviewers according to the eligibility criteria. The risk of bias was also analyzed.

Results

When applying the search strategy, 306 articles were found, after removing duplicates 277 were analyzed by title and abstract, of which 33 were selected for full reading, of which 10 met the eligibility criteria. And one was included from the additional literature search. Of these, all had a low risk of bias.

Conclusions

1. The phenomenon of osseointegration is complex and, independent of the superficial electrical charge of the implant, it may occur. To understand osseointegration, attention must be paid to the synergistic action of the electrical potential; chemical composition, intrinsic to the alloy and from surface treatment; and topography, which will determine the speed of adhesion, proliferation, and osteoblast differentiation. 2. The presence of Ca2+ deposited on the surface acts as a driving force for biomineralization that induces osteoblastic attraction and differentiation; 3. For a better understanding of the current literature, more studies are needed to describe the osteogenic regulation process through protein mediation; 4. Topography and chemical composition act as decisive parameters for cell viability independent of the attractive electrical charge.

Surface Modification of Bacterial Cellulose for Biomedical Applications

Bacterial cellulose is a naturally occurring polysaccharide with numerous biomedical applications that range from drug delivery platforms to tissue engineering strategies. BC possesses remarkable biocompatibility, microstructure, and mechanical properties that resemble native human tissues, making it suitable for the replacement of damaged or injured tissues. In this review, we will discuss the structure and mechanical properties of the BC and summarize the techniques used to characterize these properties. We will also discuss the functionalization of BC to yield nanocomposites and the surface modification of BC by plasma and irradiation-based methods to fabricate materials with improved functionalities such as bactericidal capabilities.

Toward Bactericidal Enhancement of Additively Manufactured Titanium Implants

Implant-associated infections (IAIs) are among the most intractable and costly complications in implant surgery. They can lead to surgery failure, a high economic burden, and a decrease in patient quality of life. This manuscript is devoted to introducing current antimicrobial strategies for additively manufactured (AM) titanium (Ti) implants and fostering a better understanding in order to pave the way for potential modern high-throughput technologies. Most bactericidal strategies rely on implant structure design and surface modification. By means of rational structural design, the performance of AM Ti implants can be improved by maintaining a favorable balance between the mechanical, osteogenic, and antibacterial properties. This subject becomes even more important when working with complex geometries; therefore, it is necessary to select appropriate surface modification techniques, including both topological and chemical modification. Antibacterial active metal and antibiotic coatings are among the most commonly used chemical modifications in AM Ti implants. These surface modifications can successfully inhibit bacterial adhesion and biofilm formation, and bacterial apoptosis, leading to improved antibacterial properties. As a result of certain issues such as drug resistance and cytotoxicity, the development of novel and alternative antimicrobial strategies is urgently required. In this regard, the present review paper provides insights into the enhancement of bactericidal properties in AM Ti implants.

Surface functionalization of chitosan as a coating material for orthopaedic applications: A comprehensive review

Metallic implants have dominated the biomedical implant industries for the past century for load-bearing applications, while the polymeric implants have shown great promise for tissue engineering applications. The surface properties of such implants are critical as the interaction of implant surfaces, and the body tissues may lead to unfavourable reactions. Desired implant properties are biocompatibility, corrosion resistance, and antibacterial activity. A polymer coating is an efficient and economical way to produce such surfaces. A lot of research has been carried out on chitosan (CS)-modified metallic and polymer scaffolds in the last decade. Different methods such as electrophoretic deposition, sol-gel methods, dip coating and spin coating, electrospinning, etc. have been utilized to produce CS coatings. However, a systematic review of chitosan coatings on scaffolds focussing on widely employed techniques is lacking. This review surveys literature concerning the current status of orthopaedic applications of CS for the purpose of coatings. In this review, the various preparation methods of coating, and the role of the surface functionalities in determining the efficiency of coatings are discussed. Effect of nanoparticle additions on the polymeric interfaces and in regulating the properties of surface coatings are also investigated in detail.

Antibacterial, Antibiofilm, and Antiadhesive Properties of Different Quaternized Chitosan Derivatives

In the era of antimicrobial resistance, the identification of new antimicrobials is a research priority at the global level. In this regard, the attention towards functional antimicrobial polymers, with biomedical/pharmaceutical grade, and exerting anti-infective properties has recently grown. The aim of this study was to evaluate the antibacterial, antibiofilm, and antiadhesive properties of a number of quaternized chitosan derivatives that have displayed significant muco-adhesive properties and wound healing promotion features in previous studies. Low (QAL) and high (QAH) molecular weight quaternized chitosan derivatives were synthetized and further modified with thiol moieties or pendant cyclodextrin, and their antibacterial activity evaluated as minimal inhibitory concentrations (MIC) and minimal bactericidal concentrations (MBC). The ability of the derivatives to prevent biofilm formation was assessed by crystal violet staining. Both QAL and QAH derivatives exerted a bactericidal and/or inhibitory activity on the growth of P. aeruginosa and S. epidermidis. The same compounds also showed marked dose-dependent anti-biofilm activity. Furthermore, the high molecular weight derivative (QAH) was used to functionalize titanium plates. The successful functionalization, demonstrated by electron microscopy, was able to partially inhibit the adhesion of S. epidermidis at 6 h of incubation. The shown ability of the chitosan derivatives tested to both inhibit bacterial growth and/or biofilm formation of clinically relevant bacterial species reveals their potential as multifunctional molecules against bacterial infections.

Approaches based on passive and active antibacterial coating on titanium to achieve antibacterial activity

Titanium (Ti) and its alloys are widely applied as orthopedic implants for hip and knee prosthesis, fixation, and dental implants. However, Ti and its alloys are bioinert and susceptible to bacteria and biofilm formation. Strategies for improving the antibacterial properties of Ti can be divided into two approaches, namely, passive coating and active coating on the Ti surface. Passive coating on Ti mainly kills the bacteria in contact but does not kill plankton or bacteria dwell in the bone tissue around the Ti implant. Active coating mainly involves the release of antibacterial agents to kill the bacteria, but this may result in the development of bacterial resistance. Both strategies include advantages and disadvantages. This article reviews the current and potential future approaches for improving antibacterial activity on Ti. We mainly focus on current approaches for fabricating antibacterial Ti and its limitations and countermeasures, and provide direction for further studies of biofunctionalization of Ti with antibacterial properties. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A:2531-2539, 2018.

Disulfide bond reconstruction: A novel approach for grafting of thiolated chitosan onto wool

Chitosan, a natural biopolymer, is used as a multifunctional agent for modification of wool either through chemical crosslinking or physical coating. For the first time, wool fabric has been modified with chitosan through disulfide bond breaking and reforming reactions. The chitosan was thiolated and then grafted onto the reduced wool fibers through disulfide bonds. In order to understand the mechanism of the grafting of thiolated chitosan onto wool, glutathione was used as a model compound for wool in the research. The structures of thiolated chitosan reacted with glutathione and wool fabrics grafted with thiolated chitosan were investigated by FTIR, ¹³CNMR, XPS, XRD, SEM. The dyeability, shrink-resistance and biocompatibility were also tested. The results suggested that glutathione reacted with thiolated chitosan and formed disulfide bond. The thiolated chitosan-grafted wool fabric had good shrink-resistance and dyeability. Hydrophilicity and antibacterial properties were also improved compared with untreated wool fabric. The results provide a novel approach for modification of wool through fiber-intrinsic groups like disulfide bonds.

Additively Manufactured Macroporous Titanium with Silver-Releasing Micro-/Nanoporous Surface for Multipurpose Infection Control and Bone Repair - A Proof of Concept

Restoring large-scale bone defects, where osteogenesis is slow while infections lurk, with biomaterials represents a formidable challenge in orthopedic clinics. Here, we propose a scaffold-based multipurpose anti-infection and bone repairing strategy to meet such restorative needs. To do this, personalized multifunctional titanium meshes were produced through an advanced additive manufacturing process and dual "TiO₂-poly(dopamine)/Ag (nano)" post modifications, yielding macroporous constructs with micro-/nanoporous walls and nanosilver bullets immobilized/embedded therein. Ultrahigh loading capacity and durable release of Ag⁺ were accomplished. The scaffolds were active against planktonic/adherent bacteria (Gram-negative and positive) for up to 12 weeks. Additionally, they not only defended themselves from biofilm colonization but also helped destroy existing biofilms, especially in combination with antibiotics. Further, the osteoblasts/bacteria coculture study displayed that the engineered surfaces aided MG-63 cells to combat bacterial invasion. Meanwhile, the scaffolds elicited generally acceptable biocompatibility (cell adhesion, proliferation, and viability) and hastened osteoblast differentiation and maturation (alkaline phosphatase production, matrix secretion, and calcification), by synergy of micro-/nanoscale topological cues and bioactive catecholamine chemistry. Although done ex vivo, these studies reveal that our three-in-one strategy (infection prophylaxis, infection fighting, and bone repair) has great potential to simultaneously prevent/combat infections and bridge defected bone. This work provides new thoughts to the use of enabling technologies to design biomaterials that resolve unmet clinical needs.

Managing bacterial biofilms with chitosan-based polymeric nitric oxides: Inactivation of biofilm bacteria and synergistic effects with antibiotics

In this study, we developed a new approach in the preparation of chitosan-based polymeric nitric oxides. Chitosan film (unreacted chitosan) reacted with glutaraldehyde to introduce aldehyde groups onto the material surface (glutaraldehyde-treated chitosan). Glutaraldehyde-treated chitosan reacted with a small-molecule nitric oxide donor, 3,3-bis(aminoethyl)-1-hydroxy-2-oxo-1-triazene, to covalently immobilize nitric oxide–releasing moieties onto the polymer (chitosan-based polymeric nitric oxide). Chitosan-based polymeric nitric oxide showed sustained release of nitric oxide. The activation energies and rate constants of nitric oxide release were determined. The released nitric oxide provided potent antimicrobial effects against Gram-positive and Gram-negative bacteria living in biofilms, and the chitosan-based polymeric nitric oxide film showed added/synergistic effects with common antibiotics. At 4°C, the chitosan-based polymeric nitric oxide could be stored for more than 1 month, without significantly losing nitric oxide–releasing capabilities. Furthermore, chitosan-based polymeric nitric oxide showed excellent biocompatibility with mammalian cells, pointing to great potentials of the new materials for a wide range of biomedical applications.

Interactions among osteoblastic cells, Staphylococcus aureus, and chitosan-immobilized titanium implants in a postoperative coculture system: An in vitro study

Biomaterial-related infections (BRIs) have become a major challenge in the field of orthopedic implants. In this study, we delved into the problem of BRI and attempted to reduce the possibility of BRI incidence via surface modification of titanium (Ti) with chitosan (SA-CS-Ti). To comprehensively evaluate the anti-infection potential of SA-CS-Ti, we first constructed a postoperative infection (POI) model with varying concentrations of bacteria (10²  CFU/sample and 10⁴  CFU/sample) and a constant number of SaOS-2 cells (10⁵ /sample). Then, we biologically characterized the interactions between the SaOS-2 cells, bacteria, and different Ti implants using the POI model. The results from the osteoblastic cell and bacterial attachment tests demonstrated that the SA-CS-Ti surfaces exhibit superior osteogenic behavior relative to other Ti surfaces studied while showing significant anti-infective activities in the POI model with a low infection ratio (bacteria: cell ratio of 0.001:1) 30 min after infection. Additionally, the SA-CS-Ti surfaces showed significantly reduced (p < 0.05) bacteria proliferation compared to the control Ti surfaces (UN-Ti), demonstrating their antifouling property. The significantly increased (p < 0.05) sensitivity of Staphylococcus. aureus adhered to the SA-CS-Ti surfaces against cefazolin (1 mg/L treatment) and gentamicin (10 mg/L and 100 mg/L treatment) in the coculture system augmented potential of SA-CS-Ti to be used as orthopedic implants. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 586-594, 2016.

Facile Fabrication of Lubricant-Infused Wrinkling Surface for Preventing Thrombus Formation and Infection

Despite the advanced modern biotechniques, thrombosis and bacterial infection of biomedical devices remain common complications that are associated with morbidity and mortality. Most antifouling surfaces are in solid form and cannot simultaneously fulfill the requirements for antithrombosis and antibacterial efficacy. In this work, we present a facile strategy to fabricate a slippery surface. This surface is created by combining photografting polymerization with osmotically driven wrinkling that can generate a coarse morphology, and followed by infusing with fluorocarbon liquid. The lubricant-infused wrinkling slippery surface can greatly prevent protein attachment, reduce platelet adhesion, and suppress thrombus formation in vitro. Furthermore, E. coli and S. aureus attachment on the slippery surfaces is reduced by ∼98.8% and ∼96.9% after 24 h incubation, relative to poly(styrene-b-isobutylene-b-styrene) (SIBS) references. This slippery surface is biocompatible and has no toxicity to L929 cells. This surface-coating strategy that effectively reduces thrombosis and the incidence of infection will greatly decrease healthcare costs.

Bacteria and osteoblast adhesion to chitosan immobilized titanium surface: A race for the surface

In order to evaluate the anti-infective efficacy of the titanium implant materials, two co-culture systems, a low-bacteria/osteoblast (L-B) and a high-bacteria/osteoblast system (H-B), were established. Untreated (UN-Ti), sulfuric acid-treated (SA-Ti), and chitosan immobilized titanium (SA-CS-Ti) materials were developed and evaluated. Bacteria and osteoblast behaviors, including initial attachment (evaluated at 30 mins), adhesion (evaluated at 4 h), and osteoblast spreading on each material surface were evaluated using quantification assays, scanning electron microscopy (SEM), and confocal microscopy. Quantification analysis at 30 mins showed significantly higher number of osteoblast present on SA-CS-Ti in both L-B (10,083 ± 2626) and H-B (23,592 ± 2233) than those on the UN-Ti (p<0.05). SEM observation and confocal microscopy results showed more surface area was occupied by adhered osteoblasts on SA-CS-Ti than UN-Ti and SA-Ti in both co-culture systems at 30 mins. At all time points, SA-CS-Ti had the lowest level of bacterial adhesion compared to UN-Ti and SA-Ti in both co-culture systems. A significantly (p<0.05) lower number of bacteria were recovered from SA-CS-Ti (2233 ± 681) in the H-B system compared to UN-Ti (5367 ± 1662) and SA-Ti (4533 ± 680) at 4h. Quantitative and qualitative co-culture results show the great potential of chitosan immobilization onto implant materials to prevent implant-associated infections.