Antibacterial Performance of Cu-Bearing Stainless Steel against Staphylococcus aureus and Pseudomonas aeruginosa in Whole Milk

Pathogen microorganisms exist in various environments such as dairy processing facilities. They are not easily eliminated, and significantly raise the risk of bacterial contamination. The inhibition ability of a novel type 304 Cu-bearing stainless steel （304CUSS） with nano-sized Cu-rich precipitates against Staph-ylococcus aureus （S. aureus） and Pseudomonas aeruginosa （P. aeruginosa） added whole milk was investigated in this study. The results showed that after 24 h contact, the inhibition rates of the 304CUSS against S. aureus and P. aeruginosa added whole milk reached 99.2% ± 0.3% and 99.3% ± 0.2%, respectively, in contrast with the 304SS. In the plain whole milk, the inhibition rate of the 304CUSS also reached 66.9% ± 2.0% compared with the 304SS. The results demonstrated that the 304CUSS killed majority of the planktonic bacteria, and inhibited sessile bacteria adherence to the steel surface in the whole milk with and without bacteria addition, significantly reducing the bacterial growth rate. These research outcomes explicitly show an application potential of this novel antibacterial stainless steel in the dairy related food industry.

Additively manufactured Ti–Ta–Cu alloys for the next-generation load-bearing implants

Bacterial colonization of orthopedic implants is one of the leading causes of failure and clinical complexities for load-bearing metallic implants. Topical or systemic administration of antibiotics may not offer the most efficient defense against colonization, especially in the case of secondary infection, leading to surgical removal of implants and in some cases even limbs. In this study, laser powder bed fusion was implemented to fabricate Ti3Al2V alloy by a 1:1 weight mixture of CpTi and Ti6Al4V powders. Ti-Tantalum(Ta)–Copper(Cu) alloys were further analyzed by the addition of Ta and Cu into the Ti3Al2V custom alloy. The biological,mechanical, and tribo-biocorrosion properties of Ti3Al2V alloy were evaluated. A 10 wt.% Ta(10Ta) and 3 wt.% Cu(3Cu) were added to the Ti3Al2V alloy to enhance biocompatibility and impart inherent bacterial resistance. Additively manufactured implants were investigated for resistance against Pseudomonas aeruginosa and Staphylococcus aureus strains of bacteria for up to 48 h. A 3 wt.% Cu addition to Ti3Al2V displayed improved antibacterial efficacy, i.e.78%–86% with respect to CpTi. Mechanical properties for Ti3Al2V–10Ta–3Cu alloy were evaluated, demonstrating excellent fatigue resistance, exceptional shear strength, and improved tribological and tribo-biocorrosion characteristics when compared to Ti6Al4V. In vivo studies using a rat distal femur model revealed improved early-stage osseointegration for alloys with10 wt.% Ta addition compared to CpTi and Ti6Al4V. The 3 wt.% Cu-added compositions displayed biocompatibility and no adverse infammatory response in vivo. Our results establish the Ti3Al2V–10Ta–3Cu alloy’s synergistic effect on improving both in vivo biocompatibility and microbial resistance for the next generation of load-bearing metallic implants.

Wearable pressure sensors based on antibacterial and porous chitosan hydrogels for full-range human motion detection

Wearable pressure sensors made from conductive hydrogels hold significant potential in health monitoring.However,limited pressure range(Pa to hundreds of kPa)and inadequate antibacterial properties restrict their practical applications in diagnostic and health evaluation.Herein,a wearable high-performance pressure sensor was assembled using a facilely prepared porous chitosan-based hydrogel,which was constructed from commercial phenolphthalein particles as a sacrificial template.The relationship between the porosity of hydrogels and sensing performance of sensors was systematically explored.Herein,the wearable pressure sensor,featuring an optimized porosity of hydrogels,exhibits an ultrawide sensing capacity from 4.83 Pa to 250 k Pa(range-to-limit ratio of 51,760)and high sensitivity throughout high pressure ranges(0.7 kPa~(-1),120–250 kPa).The presence of chitosan endows these hydrogels with outstanding antibacterial performance against E.coli and S.aureus,making them ideal candidates for use in wearable electronics.These features allow for a practical approach to monitor full-range human motion using a single device with a simple structure.

An ultra-thin piezoelectric nanogenerator with breathable,superhydrophobic,and antibacterial properties for human motion monitoring

Piezoelectric nanogenerators(PENGs)are promising for harvesting renewable and abundant mechanical energy with high efficiency.Up to now,published research studies have mainly focused on increasing the sensitivity and output of PENGs.The technical challenges in relation to practicability,comfort,and antibacterial performance,which are critically important for wearable applications,have not been well addressed.To overcome the limitations,we developed an all-nanofiber PENG(ANF-PENG)with a sandwich structure,in which the middle poly(vinylidene fluoride-co-hexafluoropropylene(P(VDF-HFP))/ZnO electrospun nanofibers serve as the piezoelectric layer,and the above and below electrostatic direct-writing P(VDF-HFP)/ZnO nanofiber membranes with a 110 nm Ag layer on one side that was plated by vacuum coating technique serve as the electrode layer.As the ANF-PENG only has 91μm thick and does not need further encapsulating,it has a high air permeability of 24.97 mm/s.ZnO nanoparticles in ANF-PENG not only improve the piezoelectric output,but also have antibacterial function(over 98%).The multifunctional ANF-PENG demonstrates good sensitivity to human motion and can harvest mechanical energy,indicating great potential applications in flexible self-powered electronic wearables and body health monitoring.

Polyhexamethylene biguanide chemically modified cotton with desirable hemostatic,inflammation-reducing,intrinsic antibacterial property for infected wound healing

Medical cotton dressing is cheap and widely used in diversified fields,but in the application of promoting wound healing,the continuous research of multifunctional medical cotton dressing is still of great significance.Here,we developed a fresh type of antibacterial cotton dressing through a succinct strategy based on chemically anchoring polyhexamethylene biguanide(PHMB).Intriguingly,after PHMB modification,the cotton dressing exhibited outstanding antibacterial performance which could maintain>99.99%antibacterial rate after several treatments,including washing 50 times,repeated use 10 times,UV irradiation for 7 days,cationic dyes dying,and conditioned under 90℃water bath for 2 h.In addition,the water contact angle of cotton dressing increased dramatically from 0°to 111°,which could facilitate bacterial adhesion,thus further enhance the antibacterial efficiency,and easily remove the bacterial debris.Apart from that,the developed cotton dressing showed good cytocompatibility,promoted blood clotting and expression of platelets,and promoted the wound healing process in the infection intervened skin wound model.Taken together,this antibacterial cotton dressing with desirable blood clotting,sustained protection against bacterial infection and bacterial removal features shows the potential to be a candidate for infected skin wound healing.

Electrospun PVA Nanofibrous Membranes Reinforced with Silver Nanoparticles Impregnated Cellulosic Fibers:Morphology and Antibacterial Property

To enhance the mechanical and antibacterial properties of silver nanoparticle impregnated cellulosic fibers,carboxy-cellulose nanocrystals(CCNs)were grafted with chitooligosaccharide(COS),which was used as a stabilizer for silver nanoparticles(AgNPs).Nanofibrous membranes reinforced with silver nanoparticle impregnated cellulosic fibers(CCN-COS-AgNP)were prepared via electrospinning using polyvinyl alcohol(PVA)as a matrix.The effects of CCN-COS-AgNP contents on the morphology,surface composition,mechanical properties,and antibacterial performances of the prepared CCN-COS-AgNP/PVA membranes were examined.The addition of CCN-COS-AgNP certainly improved the mechanical properties and antibacterial performances of the PVA nanofibers.The tensile strength was significantly increased from 4.40 MPa to 8.60 MPa when 8%CCN-COS-AgNP(mass ratio)was introduced.When 10%(mass ratio)CCN-COS-AgNP was added,the nanofibers showed an excellent antibacterial activity for S.aureus(Staphylococcus aureus)and E.coli(Escherichia coli),with the maximum inhibition zones of 2.30 and 1.60 cm,respectively.Moreover,the 2%(mass ratio)CCN-COS-AgNP/PVA fibrous membrane showed 126%cell viability for mg63 human osteoblasts.The electrospun PVA membrane has great potential application in biomedical field.

Preparation of green cellulose diacetate-based antibacterial wound dressings for wound healing

Managing wounds is a growing universal problem and developing effective wound dressings to staunch bleeding and protect wounds from bacterial infections is an increasingly serious challenge.In this work,a remolding electrospinning nanofiber three-dimensional structure wound dressing(CCP)was prepared with superhydrophilicity,high water absorption and absorbing capacity,excellent hemostatic capacity and antibacterial ability,and biocompatibility to promote wound healing.Polyhexamethylene guanidine hydrochloride(PHMG)was grafted to cellulose diacetate(CDA)wound dressing surface through an amide reaction.A water contact angle analysis demonstrated that CCP wound dressing could be beneficial to promote wound exudate management effectively with rapid absorption of water within 0.2 s.In vitro hemo-and cytocompatibility assay showed that a CCP wound dressing had no significant hemotoxicity or cytoxicity.Specifically,CCP wound dressings could be beneficial to accelerate wound hemostasis and further reduce mortality caused by uncontrolled bleeding.Furthermore,CCP wound dressings have an excellent antibacterial ability,which could be beneficial to inhibit wound inflammatory over-reaction and promote normal wound healing.Combined together,the prepared wound dressing in this research effort is expected to have high-potential in clinical applications.

Flexible coatings with microphase separation structure attained by copolymers and ultra-fine nanoparticles for endurable antifouling

Incorporating antibacterial agent into biomimetic coating inspired by natural organisms with micronano structure surface has generated more interest for antifouling applications.In this work,poly(dimethylsiloxane)(PDMS)-based triblock copolymers and sub-20 nm nanoparticles Ag and heterogeneous Fe_(3)O_(4)-coated Ag(Fe_(3)O_(4)@Ag)were used to construct microphase separation topography with oriented copolymer blocks structure.The artificial surface was verified by atomic force microscopy and scanning electron microscopy images.Meanwhile,the surface exhibited relative stable hydrophobic property,which was demonstrated by the water contact angle and dynamic air-bubble contact angle measurements.Consequently,after immersed in BSA solution 24 h and 720 h,the actual BSA absorption amount of the surface with Fe_(3)O_(4)@Ag nanoparticles was as low as 10%and 27%that of the initial BSA amount,respectively.Moreover,the surface also showed remarkable antibacterial performance,which effectively suppressed the growth rate of Escherichia coli.The strategy of constructing the flexible micro p hase separation structure by introducing heterogeneous inorganic antibacterial nanoparticles into a block copolymer substrate opens up a new way to create an antifouling surface coating.