A Trans-Atlantic Perspective on Stagnation in Clinical Translation of Antimicrobial Strategies for the Control of Biomaterial-Implant-Associated Infection

Trans-mucosal platforms for dental implants: Strategies to induce muco-integration and shield peri-implant diseases

OBJECTIVES

Trans-mucosal platforms connecting the bone-anchored implants to the prosthetic teeth are essential for the success of oral rehabilitation in implant dentistry. This region promotes a challenging environment for the successfulness of dental components due to the transitional characteristics between soft and hard tissues, the presence of bacteria, and mechanical forces. This review explored the most current approaches to modify trans-mucosal components in terms of macro-design and surface properties.

METHODS

This critical review article revised intensely the literature until July 2023 to demonstrate, discuss, and summarize the current knowledge about marketable and innovative trans-mucosal components for dental implants.

RESULTS

A large number of dental implant brands have promoted the development of several implant-abutment designs in the clinical market. The progress of abutment designs shows an optimistic reduction of bacteria colonization underlying the implant-abutment gap, although, not completely inhibited. Fundamental and preclinical studies have demonstrated promising outcomes for altered-surface properties targeting antibacterial properties and soft tissue sealing. Nanotopographies, biomimetic coatings, and antibiotic-release properties have been shown to be able to modulate, align, orient soft tissue cells, and induce a reduction in biofilm formation, suggesting superior abilities compared to the current trans-mucosal platforms available on the market.

SIGNIFICANCE

Future clinical implant-abutments show the possibility to reduce peri-implant diseases and fortify soft tissue interaction with the implant-substrate, defending the implant system from bacteria invasion. However, the absence of technologies translated to commercial stages reveals the need for findings to "bridge the gap" between scientific evidences published and applied science in the industry.

Potential clinical value of catheters impregnated with antimicrobials for the prevention of infections associated with peritoneal dialysis

INTRODUCTION

Peritoneal dialysis (PD) is a widely used dialysis modality, which offers the advantage of being a home therapy but is associated with a risk of potentially serious infections, including exit site infection, catheter tunnel infection, and peritonitis that may result in morbidity, technique failure, and increased mortality. Catheters impregnated with antimicrobials hold promise as a novel technique to reduce PD associated infections.

AREAS COVERED

We describe PD modalities, catheters, technique, complications, and the microbiology of associated infections, as well as standard measures to reduce the risk of infection. A novel technique for the impregnation of silicone devices with antimicrobial agents has been used to produce antimicrobial impregnated ventricular shunt catheters with proven clinical efficacy that have now been adopted as the standard of care to reduce neurosurgical infections. Using the same technology, we have developed PD and urinary catheters impregnated with sparfloxacin, triclosan, and rifampicin. Safety and tolerability have been demonstrated in urinary catheters, and a similar study is planned in PD catheters.

EXPERT OPINION

Catheters impregnated with antimicrobials offer a simple technique to reduce PD associated infections and thereby enable more people to enjoy the advantages of PD. Clinical trials are needed to establish efficacy.

Biodegradable interbody cages for lumbar spine fusion: Current concepts and future directions

Lumbar fusion often remains the last treatment option for various acute and chronic spinal conditions, including infectious and degenerative diseases. Placement of a cage in the intervertebral space has become a routine clinical treatment for spinal fusion surgery to provide sufficient biomechanical stability, which is required to achieve bony ingrowth of the implant. Routinely used cages for clinical application are made of titanium (Ti) or polyetheretherketone (PEEK). Ti has been used since the 1980s; however, its shortcomings, such as impaired radiographical opacity and higher elastic modulus compared to bone, have led to the development of PEEK cages, which are associated with reduced stress shielding as well as no radiographical artefacts. Since PEEK is bioinert, its osteointegration capacity is limited, which in turn enhances fibrotic tissue formation and peri-implant infections. To address shortcomings of both of these biomaterials, interdisciplinary teams have developed biodegradable cages. Rooted in promising preclinical large animal studies, a hollow cylindrical cage (Hydrosorb™) made of 70:30 poly-l-lactide-co-d, l-lactide acid (PLDLLA) was clinically studied. However, reduced bony integration and unfavourable long-term clinical outcomes prohibited its routine clinical application. More recently, scaffold-guided bone regeneration (SGBR) with application of highly porous biodegradable constructs is emerging. Advancements in additive manufacturing technology now allow the cage designs that match requirements, such as stiffness of surrounding tissues, while providing long-term biomechanical stability. A favourable clinical outcome has been observed in the treatment of various bone defects, particularly for 3D-printed composite scaffolds made of medical-grade polycaprolactone (mPCL) in combination with a ceramic filler material. Therefore, advanced cage design made of mPCL and ceramic may also carry initial high spinal forces up to the time of bony fusion and subsequently resorb without clinical side effects. Furthermore, surface modification of implants is an effective approach to simultaneously reduce microbial infection and improve tissue integration. We present a design concept for a scaffold surface which result in osteoconductive and antimicrobial properties that have the potential to achieve higher rates of fusion and less clinical complications. In this review, we explore the preclinical and clinical studies which used bioresorbable cages. Furthermore, we critically discuss the need for a cutting-edge research program that includes comprehensive preclinical in vitro and in vivo studies to enable successful translation from bench to bedside. We develop such a conceptual framework by examining the state-of-the-art literature and posing the questions that will guide this field in the coming years.

Challenges and solutions in polymer drug delivery for bacterial biofilm treatment: A tissue-by-tissue account

To tackle the emerging antibiotic resistance crisis, novel antimicrobial approaches are urgently needed. Bacterial communities (biofilms) are a particular concern in this context. Biofilms are responsible for most human infections and are inherently less susceptible to antibiotic treatments. Biofilms have been linked with several challenging chronic diseases, including implant-associated osteomyelitis and chronic wounds. The specific local environments present in the infected tissues further contribute to the rise in antibiotic resistance by limiting the efficacy of systemic antibiotic therapies and reducing drug concentrations at the infection site, which can lead to reoccurring infections. To overcome the shortcomings of systemic drug delivery, encapsulation within polymeric carriers has been shown to enhance antimicrobial efficacy, permeation and retention at the infection site. In this Review, we present an overview of current strategies for antimicrobial encapsulation within polymeric carriers, comparing challenges and solutions on a tissue-by-tissue basis. We compare challenges and proposed drug delivery solutions from the perspective of the local environments for biofilms found in oral, wound, gastric, urinary tract, bone, pulmonary, vaginal, ocular and middle/inner ear tissues. We will also discuss future challenges and barriers to clinical translation for these therapeutics. The following Review demonstrates there is a significant imbalance between the research focus being placed on different tissue types, with some targets (oral and wound biofims) being extensively more studied than others (vaginal and otitis media biofilms and endocarditis). Furthermore, the importance of the local tissue environment when selecting target therapies is demonstrated, with some materials being optimal choices for certain sites of bacterial infection, while having limited applicability in others.

Infections @ Trauma/Orthopedic Implants: Recent Advances on Materials, Methods, and Microbes-A Mini-Review

Implants and materials are indispensable in trauma and orthopedic surgery. The continuous improvements of implant design have resulted in an optimized mechanical function that supports tissue healing and restoration of function. One of the still unsolved problems with using implants and materials is infection. Trauma and material implantation change the local inflammatory situation and enable bacterial survival and material colonization. The main pathogen in orthopedic infections is Staphylococcus aureus. The research efforts to optimize antimicrobial surfaces and to develop new anti-infective strategies are enormous. This mini-review focuses on the publications from 2021 with the keywords S. aureus AND (surface modification OR drug delivery) AND (orthopedics OR trauma) AND (implants OR nails OR devices). The PubMed search yielded 16 original publications and two reviews. The original papers reported the development and testing of anti-infective surfaces and materials: five studies described an implant surface modification, three developed an implant coating for local antibiotic release, the combination of both is reported in three papers, while five publications are on antibacterial materials but not metallic implants. One review is a systematic review on the prevention of stainless-steel implant-associated infections, the other addressed the possibilities of mixed oxide nanotubes. The complexity of the approaches differs and six of them showed efficacy in animal studies.

Antibiotic-loaded amphora-shaped pores on a titanium implant surface enhance osteointegration and prevent infections

Artificial prostheses for joint replacement are indispensable in orthopedic surgery. Unfortunately, the implanted surface is attractive to not only host cells but also bacteria. To enable better osteointegration, a mechanically stable porous structure was created on a titanium surface using laser treatment and metallic silver particles were embedded in a hydrophilic titanium oxide layer on top. The laser structuring resulted in unique amphora-shaped pores. Due to their hydrophilic surface conditions and capillary forces, the pores can be loaded preoperative with the antibiotic of choice/need, such as gentamicin. Cytotoxicity and differentiation assays with primary human osteoblast-like cells revealed no negative effect of the surface modification with or without gentamicin loading. An in vivo biocompatibility study showed significantly enhanced osteointegration as measured by push-out testing and histomorphometry 56 days after the implantation of the K-wires into rat femora. Using a S. aureus infection model, the porous, silver-coated K-wires slightly reduced the signs of bone destruction, while the wires were still colonized after 28 days. Loading the amphora-shaped pores with gentamicin significantly reduced the histopathological signs of bone destruction and no bacteria were detected on the wires. Taken together, this novel surface modification can be applied to new or established orthopedic implants. It enables preoperative loading with the antibiotic of choice/need without further equipment or post-coating, and supports osteointegration without a negative effect of the released dug, such as gentamicin.

The future of basic science in orthopaedics and traumatology: Cassandra or Prometheus?

Orthopaedic and trauma research is a gateway to better health and mobility, reflecting the ever-increasing and complex burden of musculoskeletal diseases and injuries in Germany, Europe and worldwide. Basic science in orthopaedics and traumatology addresses the complete organism down to the molecule among an entire life of musculoskeletal mobility. Reflecting the complex and intertwined underlying mechanisms, cooperative research in this field has discovered important mechanisms on the molecular, cellular and organ levels, which subsequently led to innovative diagnostic and therapeutic strategies that reduced individual suffering as well as the burden on the society. However, research efforts are considerably threatened by economical pressures on clinicians and scientists, growing obstacles for urgently needed translational animal research, and insufficient funding. Although sophisticated science is feasible and realized in ever more individual research groups, a main goal of the multidisciplinary members of the Basic Science Section of the German Society for Orthopaedics and Trauma Surgery is to generate overarching structures and networks to answer to the growing clinical needs. The future of basic science in orthopaedics and traumatology can only be managed by an even more intensified exchange between basic scientists and clinicians while fuelling enthusiasm of talented junior scientists and clinicians. Prioritized future projects will master a broad range of opportunities from artificial intelligence, gene- and nano-technologies to large-scale, multi-centre clinical studies. Like Prometheus in the ancient Greek myth, transferring the elucidating knowledge from basic science to the real (clinical) world will reduce the individual suffering from orthopaedic diseases and trauma as well as their socio-economic impact.

The rationale behind implant coatings to promote osteointegration, bone healing or regeneration

Implant loosening, bone healing failure, implant-associated infections, and large bony defects remain challenges in orthopedic surgery. Implant surface modifications and coatings are being developed to promote osteointegration, prevent colonization by bacteria, and release bioactive factors. The following mini-review briefly discusses the clinical problem, explains the four "osteos", presents examples of coatings used for different orthopedic indications, and finally raises awareness of the coating and translational requirements.

Metallic-nanoparticle release systems for biomedical implant surfaces: effectiveness and safety

The current focus of bioengineering for implant devices involves the development of functionalized surfaces, bioactive coatings, and metallic nanoparticles (mNPs) with a controlled release, together with strategies for the application of drugs in situ, aiming at reducing infection rates, with an improvement of clinical outcomes. Controversially, negative aspects, such as cytotoxicity, mNP incorporation, bioaccumulation, acquired autoimmunity, and systemic toxicity have gained attention at the same status of importance, concerning the release of mNPs from these surface systems. The balance between the promising prospects of system releasing mNPs and the undesirable long-term adverse reactions require further investigation. The scarcity of knowledge and the methods of analysis of nanoscale-based systems to control the sequence of migration, interaction, and nanoparticle incorporation with human tissues raise hesitation about their efficacy and safety. Looking ahead, this innovative approach requires additional scientific investigation for permitting an evolution of implants without counterpoints, while updating implant surface technologies to a new level of development. This critical review has explored the promising properties of metals at the nano-scale to promote broad-spectrum bacterial control, allowing for a decrease in using systemic antibiotics. Attempts have also been made to discuss the existing limitations and the future challenges regarding these technologies, besides the negative findings that are explored in the literature.

Escherichia coli Colonization of Intestinal Epithelial Layers In Vitro in the Presence of Encapsulated Bifidobacterium breve for Its Protection against Gastrointestinal Fluids and Antibiotics

Encapsulation of probiotic bacteria can enhance their functionality when used in combination with antibiotics for treating intestinal tract infections. The interaction strength of encapsulating shells, however, varies among the encapsulation methods and impacts encapsulation. Here, we compared the protection offered by encapsulating shells with different interaction strengths toward probiotic Bifidobacterium breve against simulated gastric fluid and tetracycline, including protamine-assisted SiO2 nanoparticle yolk-shell packing (weak interaction across a void), alginate gelation (intermediate interaction due to hydrogen binding), and ZIF-8 mineralization (strong interaction due to coordinate covalent binding). The presence of encapsulating shells was demonstrated using X-ray-photoelectron spectroscopy, particulate microelectrophoresis, and dynamic light scattering. Strong interaction upon ZIF-8 encapsulation caused demonstrable cell wall damage to B. breve and slightly reduced bacterial viability, delaying the growth of encapsulated bacteria. Cell wall damage and reduced viability did not occur upon encapsulation with weakly interacting yolk-shells. Only alginate-hydrogel-based shells yielded protection against simulated gastric acid and tetracycline. Accordingly, only alginate-hydrogel-encapsulated B. breve operated synergistically with tetracycline in killing tetracycline-resistant Escherichia coli adhering to intestinal epithelial layers and maintained surface coverage of transwell membranes by epithelial cell layers and their barrier integrity. This synergy between alginate-hydrogel-encapsulated B. breve and an antibiotic warrants further studies for treating antibiotic-resistant E. coli infections in the gastrointestinal tract.

A Hyaluronic Acid Hydrogel Loaded with Gentamicin and Vancomycin Successfully Eradicates Chronic Methicillin-Resistant Staphylococcus aureus Orthopedic Infection in a Sheep Model

Implantable orthopedic devices have had an enormously positive impact on human health; however, despite best practice, patients are prone to developing orthopedic device-related infections (ODRI) that have high treatment failure rates. One barrier to the development of improved treatment options is the lack of an animal model that may serve as a robust preclinical assessment of efficacy. We present a clinically relevant large animal model of chronic methicillin-resistant Staphylococcus aureus (MRSA) ODRI that persists despite current clinical practice in medical and surgical treatment at rates equivalent to clinical observations. Furthermore, we showed that an injectable, thermoresponsive, hyaluronic acid-based hydrogel loaded with gentamicin and vancomycin outperforms current clinical practice treatment in this model, eliminating bacteria from all animals. These results confirm that local antibiotic delivery with an injectable hydrogel can dramatically increase treatment success rates beyond current clinical practice, with efficacy proven in a robust animal model.

Antimicrobial loading of nanotubular titanium surfaces favoring surface coverage by mammalian cells over bacterial colonization

Titanium is frequently used for dental implants, percutaneous pins and screws or orthopedic joint prostheses. Implant surfaces can become peri-operatively contaminated by surgically introduced bacteria during implantation causing lack of surface coverage by mammalian cells and subsequent implant failure. Especially implants that have to function in a bacteria-laden environment such as dental implants or percutaneous pins, cannot be surgically implanted while being kept sterile. Accordingly, contaminating bacteria adhering to implant surfaces hamper successful surface coverage by mammalian cells required for long-term functioning. Here, nanotubular titanium surfaces were prepared and loaded with Ag nanoparticles or gentamicin with the aim of killing contaminating bacteria in order to favor surface coverage by mammalian cells. In mono-cultures, unloaded nanotubules did not cause bacterial killing, but loading of Ag nanoparticles or gentamicin reduced the number of adhering Staphylococcus aureus or Pseudomonas aeruginosa CFUs. A gentamicin-resistant Staphylococcus epidermidis was only killed upon loading with Ag nanoparticles. However, unlike low-level gentamicin loading, loading with Ag nanoparticles also caused tissue-cell death. In bi-cultures, low-level gentamicin-loading of nanotubular titanium surfaces effectively eradicated contaminating bacteria favoring surface coverage by mammalian cells. Thus, care must be taken in loading nanotubular titanium surfaces with Ag nanoparticles, while low-level gentamicin-loaded nanotubular titanium surfaces can be used as a local antibiotic delivery system to negate failure of titanium implants due to peri-operatively introduced, contaminating bacteria without hampering surface coverage by mammalian cells.

Single-stage revision of MRSA orthopedic device-related infection in sheep with an antibiotic-loaded hydrogel

Local antimicrobial therapy is an integral aspect of treating orthopedic device-related infection (ODRI), which is conventionally administered via polymethyl-methacrylate (PMMA) bone cement. PMMA, however, is limited by a suboptimal antibiotic release profile and a lack of biodegradability. In this study, we compare the efficacy of PMMA versus an antibiotic-loaded hydrogel in a single-stage revision for chronic methicillin-resistant Staphylococcus aureus (MRSA) ODRI in sheep. Antibiofilm activity of the antibiotic combination (gentamicin and vancomycin) was determined in vitro. Swiss alpine sheep underwent a single-stage revision of a tibial intramedullary nail with MRSA infection. Local gentamicin and vancomycin therapy was delivered via hydrogel or PMMA (n = 5 per group), in conjunction with systemic antibiotic therapy. In vivo observations included: local antibiotic tissue concentration, renal and liver function tests, and quantitative microbiology on tissues and hardware post-mortem. There was a nonsignificant reduction in biofilm with an increasing antibiotic concentration in vitro (p = 0.12), confirming the antibiotic tolerance of the MRSA biofilm. In the in vivo study, four out of five sheep from each treatment group were culture-negative. Antibiotic delivery via hydrogel resulted in 10-100 times greater local concentrations for the first 2-3 days compared with PMMA and were comparable thereafter. Systemic concentrations of gentamicin were minimal or undetectable in both groups, while renal and liver function tests were within normal limits. This study shows that a single-stage revision with hydrogel or PMMA is equally effective, although the hydrogel offers certain practical benefits over PMMA, which make it an attractive proposition for clinical use.

New developments in anti-biofilm intervention towards effective management of orthopedic device related infections (ODRI's)

Orthopedic device related infections (ODRI's) represent a difficult to treat situation owing to their biofilm based nature. Biofilm infections once established are difficult to eradicate even with an aggressive treatment regimen due to their recalcitrance towards antibiotics and immune attack. The involvement of antibiotic resistant pathogens as the etiological agent further worsens the overall clinical picture, pressing on the need to look into alternative treatment strategies. The present review highlightes the microbiological challenges associated with treatment of ODRI's due to biofilm formation on the implant surface. Further, it details the newer anti-infective modalities that work either by preventing biofilm formation and/or through effective disruption of the mature biofilms formed on the medical implant. The study, therefore aims to provide a comprehensive insight into the newer anti-biofilm interventions (non-antibiotic approaches) and a better understanding of their mechanism of action essential for improved management of orthopedic implant infections.

Prevention of Prosthetic Joint Infection: From Traditional Approaches towards Quality Improvement and Data Mining

A projected increased use of total joint arthroplasties will naturally result in a related increase in the number of prosthetic joint infections (PJIs). Suppression of the local peri-implant immune response counters efforts to eradicate bacteria, allowing the formation of biofilms and compromising preventive measures taken in the operating room. For these reasons, the prevention of PJI should focus concurrently on the following targets: (i) identifying at-risk patients; (ii) reducing “bacterial load” perioperatively; (iii) creating an antibacterial/antibiofilm environment at the site of surgery; and (iv) stimulating the local immune response. Despite considerable recent progress made in experimental and clinical research, a large discrepancy persists between proposed and clinically implemented preventative strategies. The ultimate anti-infective strategy lies in an optimal combination of all preventative approaches into a single “clinical pack”, applied rigorously in all settings involving prosthetic joint implantation. In addition, “anti-infective” implants might be a choice in patients who have an increased risk for PJI. However, further progress in the prevention of PJI is not imaginable without a close commitment to using quality improvement tools in combination with continual data mining, reflecting the efficacy of the preventative strategy in a particular clinical setting.

Smart, Photothermally Activated, Antibacterial Surfaces with Thermally Triggered Bacteria-Releasing Properties

The development of effective antibacterial surfaces to prevent the attachment of pathogenic bacteria and subsequent bacterial colonization and biofilm formation is critically important for medical devices and public hygiene products. In the work reported herein, a smart antibacterial hybrid film based on tannic acid/Fe³⁺ ion (TA/Fe) complex and poly(N-isopropylacrylamide) (PNIPAAm) is deposited on diverse substrates. This surface is shown to have bacteria-killing and bacteria-releasing properties based on, respectively, near-infrared photothermal activation and subsequent cooling. The TA/Fe complex has three roles in this system: (i) as a universal adhesive "anchor" for surface modification, (ii) as a high-efficiency photothermal agent for ablation of attached bacteria (including multidrug resistant bacteria), and (iii) as a robust linker for immobilization of NH₂-terminated PNIPAAm via either Michael addition or Schiff base formation. Moreover, because of the thermoresponsive properties of the immobilized PNIPAAm, almost all of the killed bacteria and other debris can be removed from the surface simply by lowering the temperature. It is shown that this hybrid film can maintain good antibacterial performance after being used for multiple "kill-and-release" cycles and can be applied to various substrates regardless of surface chemistry or topography, thus providing a broadly applicable, simple, and reliable solution to the problems associated with surface-attached bacteria in various healthcare applications.

Enhanced bacterial killing by vancomycin in staphylococcal biofilms disrupted by novel, DMMA-modified carbon dots depends on EPS production

Alternatives for less and less effective antibiotic treatment of bacterial infections, are amongst others based on nanotechnological innovations, like carbon-dots. However, with a focus on chemistry, important characteristics of bacterial strains, like (in-)ability to produce extracellular-polymeric-substances (EPS) are often neglected. EPS is the glue that certain bacterial strains produce to keep a biofilm together. Here we report on synthesis of novel, pH-responsive, 2,3-dimethylmaleic-anhydride modified carbon-dots (C_DMMA-dots). C_DMMA-dots, like unmodified C-dots without DMMA, were little bactericidal. However, C_DMMA-dots reduced volumetric-bacterial-density within the acidic-environment of a biofilm for a non-EPS-producing Staphylococcus epidermidis strain, indicative for a more open structure. Such a structural disruption was not observed for an EPS-producing strain. Disrupted biofilms of the non-EPS-producing strain pre-exposed to C_DMMA-dots at pH 5.0, were more amenable to vancomycin penetration and killing of their inhabitants than biofilms of EPS-producing-staphylococci. Herewith, we describe a new role of carbon-dots as synthetic disruptants of biofilm structure. It is a partial success story, identifying the challenge of making carbon-dots that act as a universal disruptant for biofilms of strains with different microbiological characteristics, most notably the ability to produce or not-produce EPS. Such carbon-dots, will enable more effective clinical treatment of bacterial infections combined with current antibiotics.

Self-defensive antimicrobial biomaterial surfaces

Self-defensive biomaterial surfaces are being developed in order to mitigate infection associated with tissue-contacting biomedical devices. Such infection occurs when microbes colonize the surface of a device and proliferate into a recalcitrant biofilm. A key intervention point centers on preventing the initial colonization. Incorporating antimicrobials within a surface coating can be very effective, but the traditional means of antimicrobial delivery by continuous elution can often be counterproductive. If there is no infection, continuous elution creates conditions that promote the development of resistant microbes throughout the patient. In contrast, a self-defensive coating releases antimicrobial only when and only where there is a microbial challenge to the surface. Otherwise, the antimicrobial remains sequestered within the coating and does not contribute to the development of resistance. A self-defensive surface requires a local trigger that signals the microbial challenge. Three such triggers have been identified as: (1) local pH lowering; (2) local enzyme release; and (3) direct microbial-surface contact. This short review highlights the need for self-defensive surfaces in the general context of the device-infection problem and then reviews key biomaterials developments associated with each of these three triggering mechanisms.

Three-Dimensional Hierarchical Wrinkles on Polymer Films: From Chaotic to Ordered Antimicrobial Topographies

Microbial contamination of polymer surfaces has become a significant challenge in domestic, industrial, and biomedical applications. Recent progress in our understanding of how topographical features of different length scales can be used to effectively and selectively control the attachment and proliferation of different cell types has provided an alternative strategy for imparting antibacterial activity to these surfaces. Among the well-recognized engineered models of antibacterial surface topographies, self-organized wrinkles have shown particular promise with respect to their antimicrobial characteristics. Here, we critically review the mechanisms by which wrinkles form on the surface of different types of polymer material and how they interact with various biomolecules and cell types. We also discuss the feasibility of using this antimicrobial strategy in real-life biomedical applications.

Sodium triphosphate–capped silver nanoparticles on a decellularized scaffold-based polyurethane vascular patch for bacterial infection inhibition and rapid endothelialization

With increasing incidence rate of cardiovascular diseases and implant-related infections, there is growing demand for vascular patches that can promote endothelialization and resist bacterial infection. In this work, we immobilized sodium triphosphate–capped silver nanoparticles onto a polyurethane film to obtain a composite film and evaluated its in vitro biocompatibility. Subsequently, we anchored sodium triphosphate–capped silver nanoparticles onto a polyurethane-coated decellularized scaffold to prepare a vascular patch and investigated its in vivo performance in a mouse model. The prepared vascular patch demonstrated excellent biocompatibility and potent antibacterial activity against Escherichia coli and Staphylococcus aureus. It still maintained the surgical artery patency at 30 days after implantation. At the same time, the endothelialization at the surgical site was achieved, showing its ability to facilitate endothelialization. Therefore, it may be a promising candidate for combating bacterial infection and treating diseased blood vessels.

Artificial Channels in an Infectious Biofilm Created by Magnetic Nanoparticles Enhanced Bacterial Killing by Antibiotics

The poor penetrability of many biofilms contributes to the recalcitrance of infectious biofilms to antimicrobial treatment. Here, a new application for the use of magnetic nanoparticles in nanomedicine to create artificial channels in infectious biofilms to enhance antimicrobial penetration and bacterial killing is proposed. Staphylococcus aureus biofilms are exposed to magnetic-iron-oxide nanoparticles (MIONPs), while magnetically forcing MIONP movement through the biofilm. Confocal laser scanning microscopy demonstrates artificial channel digging perpendicular to the substratum surface. Artificial channel digging significantly (4-6-fold) enhances biofilm penetration and bacterial killing efficacy by gentamicin in two S. aureus strains with and without the ability to produce extracellular polymeric substances. Herewith, this work provides a simple, new, and easy way to enhance the eradication of infectious biofilms using MIONPs combined with clinically applied antibiotic therapies.

Penetration and Accumulation of Dendrons with Different Peripheral Composition in Pseudomonas aeruginosa Biofilms

Multidrug resistant bacterial infections threaten to become the number one cause of death by the year 2050. Development of antimicrobial dendritic polymers is considered promising as an alternative infection control strategy. For antimicrobial dendritic polymers to effectively kill bacteria residing in infectious biofilms, they have to penetrate and accumulate deep into biofilms. Biofilms are often recalcitrant to antimicrobial penetration and accumulation. Therefore, this work aims to determine the role of compact dendrons with different peripheral composition in their penetration into Pseudomonas aeruginosa biofilms. Red fluorescently labeled dendrons with pH-responsive NH₃⁺ peripheral groups initially penetrated faster from a buffer suspension at pH 7.0 into the acidic environment of P. aeruginosa biofilms than dendrons with OH or COO^- groups at their periphery. In addition, dendrons with NH₃⁺ peripheral groups accumulated near the top of the biofilm due to electrostatic double-layer attraction with negatively charged biofilm components. However, accumulation of dendrons with OH and COO^- peripheral groups was more evenly distributed across the depth of the biofilms than NH₃⁺ composed dendrons and exceeded accumulation of NH₃⁺ composed dendrons after 10 min of exposure. Unlike dendrons with NH₃⁺ groups at their periphery, dendrons with OH or COO^- peripheral groups, lacking strong electrostatic double-layer attraction with biofilm components, were largely washed-out during exposure to PBS without dendrons. Thus, penetration and accumulation of dendrons into biofilms is controlled by their peripheral composition through electrostatic double-layer interactions, which is an important finding for the further development of new antimicrobial or antimicrobial-carrying dendritic polymers.