Engineering Antifouling and Antibacterial Stainless Steel for Orthodontic Appliances through Layer-by-Layer Deposition of Nanocomposite Coatings

A Review of Antimicrobial Polymer Coatings on Steel for the Food Processing Industry

This article will focus on the issue of protection against the pathogenic biofilm development on steel surfaces within the food sectors, highlighting steel's prominence as a material choice in these areas. Pathogenic microorganism-based biofilms present significant health hazards in the food industry. Current scientific research offers a variety of solutions to the problem of protecting metal surfaces in contact with food from the growth of pathogenic microorganisms. One promising strategy to prevent bacterial growth involves applying a polymeric layer to metal surfaces, which can function as either an antiadhesive barrier or a bactericidal agent. Thus, the review aims to thoroughly examine the application of antibacterial polymer coatings on steel, a key material in contact with food, summarizing research advancements in this field. The investigation into polymer antibacterial coatings is organized into three primary categories: antimicrobial agent-releasing coatings, contact-based antimicrobial coatings, and antifouling coatings. Antibacterial properties of the studied types of coatings are determined not only by their composition, but also by the methods for applying them to metal and coating surfaces. A review of the current literature indicates that coatings based on polymers substantially enhance the antibacterial properties of metallic surfaces. Furthermore, these coatings contribute additional benefits including improved corrosion resistance, enhanced aesthetic appeal, and the provision of unique design elements.

Preparation and reverse recycling logistics of a new type of nano-filled antibacterial layer packaging film for dairy products

Introduction: Dairy products are loved by people because of their high nutritional value, but they have also become the most ideal breeding places for microorganisms. Some dairy packaging has the problem of lax sealing, resulting in products susceptible to contamination and deterioration. The harmful microorganisms and bacteria contained in them will pose a serious threat to people's health. Therefore, a good antibacterial protection is very important for dairy products. The purpose of this paper is to study the preparation and reverse recycling logistics of a new type of nano-filled antibacterial layer packaging film for dairy products. Methods: A new type of nano-filled antibacterial layer packaging film is prepared by extrusion casting method, and its mechanical properties and antibacterial properties are analyzed. Results: The experimental results in this article show that the prepared new nano-filled antibacterial layer packaging film has lower light transmittance and water vapor transmission rate, and has obvious antibacterial properties against Staphylococcus aureus and Escherichia coli, and has good barrier properties. Discussion: The antibacterial rate of the bacteria in the petri dish is as high as 99.97% after being placed for 120 days, and the antibacterial performance can be enhanced by the ratio of glycerol and starch content, and the new nano-filled antibacterial film prepared is degradable Sex, can be better recycled.

Corrosion of Fixed Orthodontic Appliances: Causes, Concerns, and Mitigation Strategies

The orthodontic supply market is a prosperous billion-dollar industry, driven by an increasing demand for orthodontic appliances. The supremacy of metallic first-generation biomaterials is evident for manufacturing brackets, archwires, bands, and other components due to their well-recognized chemical inertness, spontaneous passivation, biocompatibility, and favorable mechanical properties combination. However, the oral cavity is the ultimate corrosion-promoting environment for any metallic material. In this work, the general picture of the intraoral degradation of fixed orthodontic appliances is first addressed, from the causes to the harmful effects and their oral clinical implications. Current mitigation strategies are also pointed out, including the alloys’ bulk composition adjustment combined with new and advanced manufacturing processes and/or their surface treatment or coating deposition. The versatile use of thin films and coatings stands out with different deposition technologies: Many in vivo and in vitro efforts have been devoted to oral aging, from monolithic to composite architectures and micro- to nano-scale materials, to meet the best and safest oral practice demands. Unfortunately, literature data suggest that even the existing commercially available protective coatings have drawbacks and are fallible. Further multidisciplinary research is still required to effectively mitigate the corrosion behavior of fixed orthodontic appliances.

Chemically revised conducting polymers with inflammation resistance for intimate bioelectronic electrocoupling

Conducting polymers offer attractive mixed ionic-electronic conductivity, tunable interfacial barrier with metal, tissue matchable softness, and versatile chemical functionalization, making them robust to bridge the gap between brain tissue and electronic circuits. This review focuses on chemically revised conducting polymers, combined with their superior and controllable electrochemical performance, to fabricate long-term bioelectronic implants, addressing chronic immune responses, weak neuron attraction, and long-term electrocommunication instability challenges. Moreover, the promising progress of zwitterionic conducting polymers in bioelectronic implants (≥4 weeks stable implantation) is highlighted, followed by a comment on their current evolution toward selective neural coupling and reimplantable function. Finally, a critical forward look at the future of zwitterionic conducting polymers for in vivo bioelectronic devices is provided.

Functional Surface Coatings on Orthodontic Appliances: Reviews of Friction Reduction, Antibacterial Properties, and Corrosion Resistance

Surface coating technology is an important way to improve the properties of orthodontic appliances, allowing for reduced friction, antibacterial properties, and enhanced corrosion resistance. It improves treatment efficiency, reduces side effects, and increases the safety and durability of orthodontic appliances. Existing functional coatings are prepared with suitable additional layers on the surface of the substrate to achieve the abovementioned modifications, and commonly used materials mainly include metal and metallic compound materials, carbon-based materials, polymers, and bioactive materials. In addition to single-use materials, metal-metal or metal-nonmetal materials can be combined. Methods of coating preparation include, but are not limited to, physical vapor deposition (PVD), chemical deposition, sol-gel dip coating, etc., with a variety of different conditions for preparing the coatings. In the reviewed studies, a wide variety of surface coatings were found to be effective. However, the present coating materials have not yet achieved a perfect combination of these three functions, and their safety and durability need further verification. This paper reviews and summarizes the effectiveness, advantages and disadvantages, and clinical perspectives of different coating materials for orthodontic appliances in terms of friction reduction, antibacterial properties, and enhanced corrosion resistance, and discusses more possibilities for follow-up studies as well as for clinical applications in detail.

Mussel-Inspired Multicomponent Codeposition Strategy toward Antibacterial and Lubricating Multifunctional Coatings on Bioimplants

Bacterial infections and limited surface lubrication are the two key challenges for bioimplants in dynamic contact with tissues. However, the simultaneous lubricating and antibacterial properties of the bioimplants have rarely been investigated. In this work, we successfully developed a multifunctional coating with simultaneous antibacterial and lubricating properties for surface functionalization of bioimplant materials. The multifunctional coating was fabricated on a polyurethane (PU) substrate via polydopamine (PDA)-assisted multicomponent codeposition, containing polyethyleneimine (PEI) and trace amounts of copper (Cu) as synergistic antibacterial components and zwitterionic poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) as the lubricating component. The obtained PDA(Cu)/PEI/PMPC coating showed excellent antibacterial activity (antibacterial efficiency: ∼99%) to both Escherichia coli and Staphylococcus aureus compared with bare PU. The excellent antibacterial properties were attributed to the combined effect of anti-adhesion capability of hydrophilic PMPC and PEI and bactericidal activity of Cu in the coating. Meanwhile, the coefficient of friction of the coating was significantly decreased by ∼52% compared with bare PU owing to the high hydration feature of PMPC, suggesting the superior lubricating property. Furthermore, the PDA(Cu)/PEI/PMPC coating was highly biocompatible toward human umbilical vein endothelial cells demonstrated by in vitro cytotoxicity tests. This study not only contributes to the chemistry of PDA-assisted multicomponent codeposition but also provides a facile and practical way for rational design of multifunctional coatings for medical devices.

Organic Bioelectronics for In Vitro Systems

Bioelectronics have made strides in improving clinical diagnostics and precision medicine. The potential of bioelectronics for bidirectional interfacing with biology through continuous, label-free monitoring on one side and precise control of biological activity on the other has extended their application scope to in vitro systems. The advent of microfluidics and the considerable advances in reliability and complexity of in vitro models promise to eventually significantly reduce or replace animal studies, currently the gold standard in drug discovery and toxicology testing. Bioelectronics are anticipated to play a major role in this transition offering a much needed technology to push forward the drug discovery paradigm. Organic electronic materials, notably conjugated polymers, having demonstrated technological maturity in fields such as solar cells and light emitting diodes given their outstanding characteristics and versatility in processing, are the obvious route forward for bioelectronics due to their biomimetic nature, among other merits. This review highlights the advances in conjugated polymers for interfacing with biological tissue in vitro, aiming ultimately to develop next generation in vitro systems. We showcase in vitro interfacing across multiple length scales, involving biological models of varying complexity, from cell components to complex 3D cell cultures. The state of the art, the possibilities, and the challenges of conjugated polymers toward clinical translation of in vitro systems are also discussed throughout.

Phosphonate/zwitterionic/cationic terpolymers as high-efficiency bactericidal and antifouling coatings for metallic substrates

Bacteria associated infection is a critical challenge for metallic implants and devices in biomedical applications. Here, we report phosphonate/zwitterionic/quaternary amine terpolymers as a new type of antifouling and bactericidal coating for metallic substrates. Through reversible-addition fragmentation chain transfer polymerization (RAFT) and quaternization, well-controlled phosphonate/zwitterionic/cationic terpolymers with identical phosphonate segments (repeat units of 15) and varied zwitterionic and cationic components (nSBMA : nTMAEMA = 64 : 0, 54 : 18, 18 : 32, 9 : 52, and 0 : 70) were precisely prepared. The polymers can be coated on TC4 substrates based on the strong coordination between phosphonate groups and metallic substrates, as evidenced by water contact angle and XPS tests. Bactericidal evaluation revealed that the antibacterial efficiency was enhanced with the increase of cationic content in the coating polymers. TC4 substrates coated with the polymer coating with a cationic segment of 70 repeat units were able to kill 97.5 and 94.0% of S. aureus and E. coli, respectively. By virtue of the antifouling ability of the zwitterionic component and the bactericidal ability of the cationic component, the antibacterial efficiency was increased to 99.5% without significant compromising of the cytocompatibility. Meanwhile, the dual functional terpolymers could be easily applied on other metallic substrates, such as titanium, stainless steel, and Ni/Cr alloy, which were able to kill up to 97.9% of S. aureus and 99.9% of E. coli, respectively, endowing the excellent antibacterial properties to general bio-metals. The high-efficiency antibacterial modification strategy demonstrated here may find many applications on metallic implants and devices to combat bacterial associated infections.

In Vitro Bioactivity and Antibacterial Activity of Strontium-, Magnesium-, and Zinc-Multidoped Hydroxyapatite Porous Coatings Applied via Atmospheric Plasma Spraying

The beneficial effects of Sr- and Mg-doped hydroxyapatite (HAp) on osteoblast proliferation and bone regeneration have been investigated in the past, and the antibacterial ability of Zn ions is well known. However, HAp coatings doped with these three elements via thermal spraying have not yet been investigated. In this study, HAp powder was synthesized at different pH values (4, 6, 8, and 10) and calcined at different temperatures (200, 400, 600, 800, and 1000 °C) to obtain HAp with the highest purity. Subsequently, strontium-, magnesium-, and zinc-doped HAp powders were synthesized at the optimal pH value and calcination temperature. The HAp powder was then coated onto Ti disks using atmospheric plasma spraying (APS) or vapor-induced pore-forming atmospheric plasma spraying (VIPF-APS) techniques at different working currents (350, 400, and 450 A) and spraying distances (10 and 15 cm). X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy equipped with energy-dispersive spectroscopy were used for material characterization to determine the optimal parameters. With these optimal coating parameters, HAp, Zn-HAp, SrMg-HAp, and ZnSrMg-HAp powders were deposited onto the Ti disks using VIPF-APS and named HAp-Ti, Zn-HAp-Ti, SrMg-HAp-Ti, and ZnSrMg-HAp-Ti, respectively. The in vitro bioactivity of these four groups was evaluated using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and alkaline phosphatase (ALPase) activity assay. Besides, the antibacterial activities against Prevotella nigrescens, Porphyromonas gingivalis, and Fusobacterium nucleatum were assessed. The results showed that the purity of HAp synthesized at pH 10 and 800 °C was 98.40%. A porous coating without cracks was obtained at a 10 cm spraying distance and 400 A working current using VIPF-APS. SrMg-HAp-Ti and ZnSrMg-HAp-Ti resulted in higher osteoblast proliferation and ALPase activity than the control. Moreover, both Zn-HAp-Ti and ZnSrMg-HAp-Ti exhibited antibacterial activity against the three bacteria. Therefore, ZnSrMg-HAp has potential as a coating for biomedical materials due to its ability to reduce bacterial infection and enhance osseointegration.

A mussel-bioinspired multi-functional hyperbranched polymeric coating with integrated antibacterial and antifouling activities for implant interface modification

On the basis of a function integrating strategy, a mussel-inspired hyperbranched polymeric coating with antibacterial and antifouling properties was ingeniously designed and synthesized for the interface modification of implants.