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Surface modification of hemocompatible copolymers on silicone elastomers (SEs) is crucial for the long-term use of medical devices. Both physical adsorption and chemical conjugation are important for modification of SE. Oxygen plasma treatment is widely used to produce silanol groups on SE for silane coupling. However, the plasma reaction is difficult to apply to the surface modification of three-dimensional complex devices. This study demonstrated an appropriate and efficient method with alkaline solution for producing silanol groups on SE for modifying phosphorylcholine-based copolymer with organosilane (cross-MPC copolymer). A 2.5 wt% aqueous solution of potassium hydroxide (KOH) was effective in producing silanol groups and for coating the cross-MPC copolymer. Additionally, we successfully modified the cross-MPC copolymer on the inner surface of SE tubes after pretreatment with the 2.5 wt% KOH aqueous solution, and the copolymer film was coated homogeneously. The cross-MPC copolymer film on SE was stable for one month under fluidic condition with a shear stress of 3.2 Pa. The hollow fiber membrane with the polymer coating inhibited blood coagulation after one week implantation with extracorporeal circulation device using a goat. Therefore, pretreatment of SE using an alkaline solution is an appropriate method for producing silanol groups for coating the cross-MPC copolymer by silane-coupling reaction.

Background: This study was designed to evaluate the long-term durability, oxygenation, and pressure loss of newly developed, methacryloyloxyethyl phosphorylcholine (MPC)-polymer-coated, nonporous silicone hollow fiber-membrane lungs in vivo using a pulmonary artery-to-left-atrium paracorporeal configuration., Methods: An extracorporeal circuit from the pulmonary artery (device inflow) to the left atrium (device outflow) was established using dedicated composite vascular grafts in three healthy female goats for the prototype lung testing., Results: Duration of testing the prototype lungs was 52, 57, or 100 days. Averages of oxygen transfer rates (ml/min) at the beginning of the evaluation were 77.6 ± 17.5 at 1 L/min blood flow, 137.1 ± 58.0 at 2 L/min, and 188.9 ± 86.4 at 3 L/min. Consistent oxygen transfer performance was maintained throughout the experiments. Electron microscopy revealed minimal thrombus formation on the hollow fiber membranes inside the lungs. Native lungs were maintained in good condition without appreciable congestion in all three subjects., Conclusions: The longevity of the hollow fibers documented here is a key requirement for the development of a device for long-term respiratory support. The pulmonary artery-to-left-atrial configuration established with our composite vascular grafts could maintain long-term functionality., (© 2024 The Author(s). Artificial Organs published by International Center for Artificial Organ and Transplantation (ICAOT) and Wiley Periodicals LLC.)

Drug-eluting stents (DES) are the best choice of the current era to open the occluded arteries. Its success depends upon the concentration of the drug and overall release kinetics, which in turn is subjected to the polymeric drug carrier and mechanism of drug release at the target area. Each generation of DES possess different characteristics based on different aspects i.e., polymer type, coating layer thickness, and drug concentration have been discussed. This review paper discusses all the polymers utilized in DES systems and their release profiles when combined with multiple drugs for the treatment of coronary heart disease. Drug-coated metal stents are used to support and improve the quality of life of patients with cardiovascular diseases. This review describes the properties of drug-eluting stent from different generations and challenges they offered. Nature of polymeric drug carriers affects the inflammation, lesion healing, rate of restenosis, and thrombosis. Ongoing research in DES technology aims to avoid the challenges offered by non-erodible polymeric drug carriers. Third-generation DES utilizes PLA-based polymers which are biocompatible, flexible, and erodible. Bioresorbable DES is future of DES technology; however, it is still in primitive stages and overcoming the issues of mechanical strength and corrosion. [ABSTRACT FROM AUTHOR]

The aim of this project is to fabricate hydrogen-rich silicone doped with magnetic nanoparticles for use as a temperature change indicator in magnetic resonance imaging-guided (MRIg) thermal ablations. To avoid clustering, the particles of mixed MnZn ferrite were synthesized directly in a medical-grade silicone polymer solution. The particles were characterized by transmission electron microscopy, powder X-ray diffraction, soft X-ray absorption spectroscopy, vibrating sample magnetometry, temperature-dependent nuclear magnetic resonance relaxometry (20 °C to 60 °C, at 3.0 T), and magnetic resonance imaging (at 3.0 T). Synthesized nanoparticles were the size of 4.4 nm ± 2.1 nm and exhibited superparamagnetic behavior. Bulk silicone material showed a good shape stability within the study's temperature range. Embedded nanoparticles did not influence spin–lattice relaxation, but they shorten the longer component of spin–spin nuclear relaxation times of silicone's protons. However, these protons exhibited an extremely high r2* relaxivity (above 1200 L s−1 mmol−1) due to the presence of particles, with a moderate decrease in the magnetization with temperature. With an increased temperature decrease of r2*, this ferro–silicone can be potentially used as a temperature indicator in high-temperature MRIg ablations (40 °C to 60 °C). [ABSTRACT FROM AUTHOR]

Antibiotic resistance continues to be a most serious threat to public health. This situation demands that the scientific community increase their efforts for the discovery of alternative strategies to circumvent the problems associated with conventional small molecule therapeutics. The Global Antimicrobial Resistance and Use Surveillance System (GLASS) Report (published in June 2021) discloses the rapidly increasing number of bacterial infections that are mainly caused by antimicrobial-resistant bacteria. These concerns have initiated various government agencies and other organizations to educate the public regarding the appropriate use of antibiotics. This review discusses a brief highlight on the timeline of antimicrobial drug discovery with a special emphasis on the historical development of antimicrobial resistance. In addition, new antimicrobial targets and approaches, recent developments in drug screening, design, and delivery were covered. This review also discusses the emergence and roles of various antibiotic adjuvants and combination therapies while shedding light on current challenges and future perspectives. Overall, the emergence of resistant microbial strains has challenged drug discovery but their efforts to develop alternative technologies such as nanomaterials seem to be promising for the future. [ABSTRACT FROM AUTHOR]

The fabrication of macromolecular architectures with high aspect ratio and well‐defined internal and external morphologies remains a challenge. The combination of template chemistry and self‐assembly concepts to construct peculiar polymer architectures via a bottom‐up approach is an emerging approach. In this study, a cylindrical template—namely a core–shell molecular polymer brush—and linear diblock copolymers (DBCP) associate to produce high aspect ratio polymer particles via interpolyelectrolyte complexation. Induced, morphological changes are studied using cryogenic transmission electron and atomic force microscopy, while the complexation is further followed by isothermal titration calorimetry and ξ‐potential measurements. Depending on the nature of the complexing DBCP, distinct morphological differences can be achieved. While polymers with a non‐ionic block lead to internal compartmentalization, polymers featuring zwitterionic domains lead to a wrapping of the brush template. [ABSTRACT FROM AUTHOR]

Antibiotic resistance due to suboptimal targeting and inconsistent antibiotic release at bacterial infection sites has driven the formulation of stimuli‐responsive nanocarriers for antibacterial therapy. Unlike conventional nanocarriers, stimuli‐responsive nanocarriers have the ability to specifically enhance targeting and drug release profiles. There has been a significant escalation in the design and development of novel nanomaterials worldwide; in particular, intrinsic stimuli‐responsive antibiotic nanocarriers, due to their enhanced activity, improved targeted delivery, and superior potential for bacterial penetration and eradication. Herein, we provide an extensive and critical review of pH‐, enzyme‐, redox‐, and ionic microenvironment‐responsive nanocarriers that have been reported in literature to date, with an emphasis on the mechanisms of drug release, the nanomaterials used, the nanosystems constructed and the antibacterial efficacy of the nanocarriers. The review also highlights further avenues of research for optimizing their potential and commercialization. This review confirms the potential of intrinsic stimuli‐responsive nanocarriers for enhanced drug delivery and antibacterial killing. This article is categorized under:Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious DiseaseNanotechnology Approaches to Biology > Nanoscale Systems in Biology [ABSTRACT FROM AUTHOR]

With a growing health threat of bacterial resistance to antibiotics, the nanomaterials have been extensively studied as an alternative. It is assumed that antimicrobial nanomaterials can affect bacteria by several mechanisms simultaneously and thereby overcome antibiotic resistance. Another promising potential use is employing nanomaterials as nanocarriers for antibiotics in order to overcome bacterial defense mechanisms. The passive targeting of nanomaterials is the often used strategy for bacterial treatment, including intracellular infections of macrophages. Furthermore, the specific targeting enhances the efficacy of antimicrobials and reduces side effects. This review aims to discuss advantages, disadvantages, and challenges of nanomaterials in the context of the targeting strategies for antimicrobials as advanced tools for treatments of bacterial infections. This article is categorized under:Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease [ABSTRACT FROM AUTHOR]

This study evaluated the effect of experimental coatings, containing zwitterion or hydrophilic monomers, on the adherence ofCandida albicans,Candida glabrata,andStreptococcus mutansto an acrylic resin. Acrylic samples (smooth or rough surfaces) were left untreated (control) or coated with one of the following experimental coatings: 3-hydroxypropylmethacrylate (HP) or sulfobetaine methacrylate (S), at concentrations of 25, 30, or 35%. Half of the specimens were coated with saliva. The adhesion test was performed by incubating specimens inC. albicans,C. glabrata, andS. mutanssuspensions at 37°C for 90 min. The number of adhered microorganisms was determined by metabolic activity (XTT) and by cell viability (CFU). All coated specimens exhibited lower absorbance and CFU values compared to control specimens. Saliva and roughness did not promote microorganism adherence. An XPS analysis confirmed the modification in the chemical composition of the coatings in the experimental samples. These experimental coatings significantly reduced the adherence ofC. albicans,C. glabrataandS. mutansto acrylic resin. [ABSTRACT FROM AUTHOR]

Background: Ligand targeted therapy (LTT) is a powerful pharmaceutical strategy to achieve selective drug delivery to pathological cells, for both therapeutic and diagnostic purposes, with the advantage of limited side effects and toxicity. This active drug targeting approach is based on the discovery that there are receptors overexpressed on pathological cells, compared to their expression in normal tissues. Purpose: The purpose of this article is to review recently published data on LTT with applications, both in the field of cancer therapy and other diseases. Moreover, data on LTT exploiting receptors overexpressed at cytoplasmatic level are also reviewed. Methods: Data were deduced from Medline (PubMed) and SciFinder and their selections were made with preference to papers where the most relevant receptors were involved. Results: Several groups have reported improved delivery of targeted nanocarriers, as compared to nontargeted ones, to pathological cells. LTT offers several advantages, but there are also limitations in the development of this strategy. Moreover, LTT have shown encouraging results in in vitro and in animal models in vivo; hence their clinical potential awaits investigation. Conclusion: Recent studies highlight that the ligand density plays an important role in targeting efficacy. Furthermore, LTT applications in diseases different from cancer and those exploiting receptors overexpressed at cytoplasmatic level are growing. [ABSTRACT FROM AUTHOR]

Intravascular catheters (IVCs) and other medical tubing are commonly made of polymeric materials such as polyurethane (PU). Polymers tend to be fouled by surface absorption of proteins and platelets, often resulting in the development of bacterial infections and thrombosis during catheterization, which can lead to embolism and death. Existing solutions to fouling are based on coating the IVCs with hydrophilic, anti-thrombogenic, or antimicrobial materials. However, the delamination of the coatings themselves is associated with significant morbidity, as reported by the United States Food and Drug Administration (FDA). We developed a lubricious, antimicrobial, and antithrombogenic coating complex, which can be covalently attached to the surface of industrial PU catheters. The coating complex is pre-synthesized and comprises 2-methacryloyloxyethyl phosphorylcholine (MPC) as an antifouling agent, covalently attached to branched polyethyleneimine (bPEI) as a lubricating agent. The two-step coating procedure involves PU-amine surface activation using a diisocyanate, followed by chemical grafting of the bPEI-S-MPC complex. Compared with neat PU, the coating was found to reduce the coefficient of friction of the IVC surface by 30% and the hemolysis ratio by more than 50%. Moreover, the coating exhibited a significant antimicrobial activity under JIS Z2801:2000 standard compared with neat PU. Finally, in in-vivo acute rabbit model studies, the coating exhibited significant antithrombogenic properties, reducing the thrombogenic potential to a score of 1.3 on coated surfaces compared with 3.3 on uncoated surfaces. The materials and process developed could confer lubricious, antithrombogenic, and antimicrobial properties on pre-existing PU-based catheters. [ABSTRACT FROM AUTHOR]