Co, Ni, Cu, Zn, Hg) and metalloids from group 13-16 of the periodic table (e.g., Al, Ga, As, Sn, Sb, Pb, Bi) have increasingly Copper (Cu) and its alloys have been shown to eradicate a wide range of multidrug-resistant microbes upon direct contact. In this study, a facile one-step laser texturing (LT) process is demonstrated to effectively enhance the bactericidal properties of copper surfaces via concurrent selective modification of surface topography and chemistry of laser textured copper (LT-Cu). Surface morphology and elemental composition are analyzed via field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), and Raman spectroscopy. Surface area and pore size of LT-Cu is determined by Barrett-Joyner-Halenda (BJH) and Brunauer-Emmett-Teller (BET) analysis. It reveals direct formation of mesoporous structures with higher surface oxide (Cu 2 O and CuO), which provide a highly stable superhydrophilic property to the LT-Cu surfaces. The antibacterial properties of LT-Cu are tested against pathogenic bacterial strains with different concentrations including Pseudomonas aeruginosa, and methicillinresistant Staphylococcus aureus (MRSA USA300) at 10 5 CFU mL −1 , and Escherichia coli and Staphylococcus aureus at high bacterial concentrations of 10 8 CFU mL −1 using standard contact killing tests. The analysis shows that LT-Cu needs 40, 90, 60, and 120 min to completely eradicate the respective bacterial strain. The LT-Cu causes membrane damage to the bacterial cells immediately after exposure. Furthermore, the biocompatibility of LT-Cu is investigated by in vitro immune-staining assays with mammary stromal fibroblasts and T4-2 cells.

Chronic nonhealing wounds are a growing socioeconomic problem that affects more than 6 million people annually solely in the United States. These wounds are colonized by bacteria that often develop into biofilms that act as a physical and chemical barrier to therapeutics and tissue oxygenation leading to chronic inflammation and tissue hypoxia. Although wound debridement and vigorous mechanical abrasion techniques are often used by clinical professionals to manage and remove biofilms from wound surfaces, such methods are highly nonselective and painful. In this study, we have developed a flexible polymer composite microneedle array that can overcome the physicochemical barriers (i.e., bacterial biofilm) present in chronic nonhealing wounds and codeliver oxygen and bactericidal agents. The polymeric microneedles are made by using a facile UV polymerization process of polyvinylpyrrolidone and calcium peroxide onto a flexible polyethylene terephthalate substrate for conformable attachment onto different locations of the human body surface. The microneedles effectively elevate the oxygen levels from 8 to 12 ppm once dissolved over the course of 2 h while also providing strong bactericidal effects on both liquid and biofilm bacteria cultures of both Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa) bacterial strains commonly found in dermal wounds. Furthermore, the results from the ex vivo assay on a porcine wound model indicated successful insertion of the microneedles into the tissue while also providing effective bactericidal properties against both Gram-positive and Gram-negative within the complex tissue matrix. Additionally, the microneedles demonstrate high levels of cytocompatibility with less than 10% of apoptosis throughout 6 days of continuous exposure to human dermal fibroblast cells. The demonstrated flexible microneedle array can provide a better approach for increasing the effectiveness of topical tissue oxygenation as well as the treatment of infected wounds with intrinsically antibiotic resistant biofilms.

No abstract

Wound-associated infections are a significant and rising health concern throughout the world owing to aging population, prevalence of diabetes, and obesity. In addition, the rapid increase of life-threatening antibiotic resistant infections has resulted in challenging wound complications with limited choices of effective therapeutics. Recently, topical ozone therapy has shown to be a promising alternative approach for treatment of non-healing and infected wounds by providing strong antibacterial properties while stimulating the local tissue repair and regeneration. However, utilization of ozone as a treatment for infected wounds has been challenging thus far due to the need for large equipment usable only in contained, clinical settings. This work reports on the development of a portable topical ozone therapy system comprised of a flexible and disposable semipermeable dressing connected to a portable and reusable ozonegenerating unit via a flexible tube. The dressing consists of a multilayered structure with gradient porosities to achieve uniform ozone distribution. The effective bactericidal properties of the ozone delivery platform were confirmed with two of the most commonly pathogenic bacteria found in wound infections, Pseudomonas aeruginosa and Staphylococcus epidermidis. Furthermore, cytotoxicity tests with human fibroblasts cells indicated no adverse effects on human cells.

a broad spectrum of applications due to their unique characteristics such as high mechanical flexibility, low cost, and scalable manufacturing. [1][2][3][4] However, many of the materials and processes used in PE devices often depend on nonbiodegradable polymer supporting substrates (such as silicone elastomers, polyethylene terephthalate, polyimide, etc.). [5][6][7][8][9] Considering the widespread implementation of PE, spanning from soft robots, human-machine interface, and flexible displays to advanced healthcare and virtual reality in the near future, the buildup of discarded electronic waste (e-waste) will cause adverse environmental effects. Recently, the United Nations has reported that by 2030 e-waste will grow up to 74 million metric tons on the planet, which will demand extensive landfill space for its appropriate disposal or recycling. [10] Therefore, researchers and scientists are highly inspired to find sustainable substitutes with the desired characteristics to address the concerns mentioned above.Recently, paper-based transient bioelectronics (PTB) composed of biodegradable materials have emerged as a new class of technology that can fully degrade to benign and environmentally safe by-products after they have served their primary function. [11][12][13][14] Despite the known bioresorbable characteristics of the paper substrates in PTB, the conductive traces and circuitry in these devices must be made from highly conductive and bioresorbable materials through Paper-based electronics are emerging as a new class of technology with broad areas of application. Despite several efforts to fabricate new types of flexible electronic devices by screen printing of conductive paste, many of them are often nonbiodegradable, toxic, and expensive, limiting their practical use in bioresorbable paper-based electronics. To address this need, a highly conductive and biodegradable bimodal conductive paste is developed using cost-effective zinc-based micro and nanoparticles with a facile low-temperature sintering process compatible with paper substrates. The two-step sintering process involves the removal of the insulating zinc oxide layer by spray coating acetic acid followed by a heat press sintering process to ensure the formation of highly packed and continuous metallic traces. The required conditions for the heat press sintering process are systematically studied using electrical, optical, and mechanical characterization techniques. The results of these investigations revealed an ultra-packed microstructure with high electrical conductivity (0.5 × 10 5 S m −1 ) and low oxide content that is obtained with a heat press sintering setting of 220 °C for 60 s. Finally, as a proof of concept, the conductive paste with an optimized sintering process is used to fabricate a wearable wireless heater for remote-controlled release of therapeutics. The controlled delivery of the system is validated in the practical and on-demand delivery of antibiotics for eradicating commonly found bacteria such as Staphylococcus aureus in derm...

The problematic combination of a rising prevalence of skin and soft tissue infections and the growing rate of life-threatening antibiotic resistant infections presents an urgent, unmet need for the healthcare industry. These evolutionary resistances originate from mutations in the bacterial cell walls which prevent effective diffusion of antibiotics. Gram-negative bacteria are of special consideration due to the natural resistance to many common antibiotics due to the unique bilayer structure of the cell wall. The system developed here provides one solution to this problem through a wearable therapy that delivers and utilizes gaseous ozone as an adjunct therapy with topical antibiotics through a novel dressing with drug-eluting nanofibers (NFs). This technology drastically increases the sensitivity of Gram-negative bacteria to common antibiotics by using oxidative ozone to bypass resistances created by the bacterial cell wall. To enable simple and effective application of adjunct therapy, ozone delivery and topical antibiotics have been integrated into a single application patch. The drug delivery NFs are generated via electrospinning in a fast-dissolve PVA mat without inducing decreasing gas permeability of the dressing. A systematic study found ozone generation at 4 mg/h provided optimal ozone levels for high antimicrobial performance with minimal cytotoxicity. This ozone treatment was used with adjunct therapy delivered by the system in vitro. Results showed complete eradication of Gram-negative bacteria with ozone and antibiotics typically used only for Gram-positive bacteria, which showed the strength of ozone as an enabling adjunct treatment option to sensitize bacteria strains to otherwise ineffective antibiotics. Furthermore, the treatment is shown through biocompatibility testing to exhibit no cytotoxic effect on human fibroblast cells.

No abstract

Enhancement of intensity and wavelength tunability of emission are desirable features for light emitting device applications. We report on the large and tunable blue shift (60 nm) in emission from an environment-sensitive fluorophore (Coumarin153) embedded in Ag plasmonic random media. Coumarin 153 having emission at 555 nm, show a systematic blue shift (to 542 nm, 503 nm and 495 nm ) upon infiltration into random media fabricated by Ag nanowires of different aspect ratio (hence surface plasmon resonances at 426 nm, 445 nm, 464 nm). The blue shift is due to fast dynamic surface enhanced fluorescence mechanism and can be tuned by controlling the surface plasmon resonance and hotspot density in random media. Enhanced emission at desired wavelength is achieved by using nanostructures having higher extinction coefficient but same surface plasmon resonance. Ag nanostructures of different aspect ratio used for fabricating the random media are synthesized by chemical route.