Development of acid-free chitosan films in food coating applications: Provolone cheese as a case study

Chitosan has been extensively explored in food coatings. Still, its practical application is largely hampered by its conventional wet processing in acetic acid, whose residuals negatively impact food quality and safety. Here, we propose a new method to formulate chitosan coatings for food applications by avoiding organic acid processing and validate them on a cheese model. The procedure entails modifying a previously reported process based on HCl chitosan treatment and neutralising the resulting gel. The obtained chitosan is solubilised in water using carbonic acid that forms in situ by dissolving carbon dioxide gas. The reversibility of water carbonation allows for easy removal of carbonic acid residues, resulting in acid-free chitosan films and coatings. The performance of the coating was tested against state-of-the-art chitosan-based and polymeric coatings. We preliminarily characterised the films' properties (water stability, barrier, and optical properties). Then, we assessed the performance of the coating on Provolone cheese as a food model (mass transfer and texture profiles over 14 days). The work demonstrated the advantage of the proposed approach in solving some main issues of food quality and safety, paving the way for an effective application of chitosan in future food contact applications.

Dialdehyde cellulose (DAC) and polyethyleneimine (PEI) coated polyvinylidene fluoride (PVDF) membrane for simultaneously removing emulsified oils and anionic dyes

Developing high-efficiency membrane for oil and dye removal is very urgent, because wastewater containing them can cause great damage to human and environment. In this study, a coated membrane was fabricated by applying DAC and PEI onto the commercial PVDF microfiltration membrane for supplying the demand. The coated membrane presents superhydrophlic and superoleophobic properties with a water contact angle of 0o and underwater oil contact angle exceed 150°, as well as excellent low underwater oil adhesion performance. The coated membrane shows high separation efficiency exceeded 99.0% and flux 350.0 L·m-2·h-1 when used for separating for six kinds of oil including pump oil, sunflower oil, n-hexadecane, soybean oil, diesel and kerosene in water emulsions. Additionally, the coated membrane can effectively remove anionic dyes, achieving rejection rates of 94.7%, 93.4%, 92.3%, 90.7% for the CR, MB, RB5, AR66, respectively. More importantly, the membrane was able to simultaneously remove emulsified oil and soluble anionic dyes in wastewater containing both of them. Therefore, this novel coated membrane can be a promising candidate for treating complex wastewater.

Capillary electrophoresis using triple layer modified capillary facilitating salivary ion analyses: Application to search for potential stress markers induced by cold pressure test

In this study, we introduce a novel approach for the analysis of salivary ions using capillary electrophoresis (CE) with a triple-layer coated capillary. The capillary is sequentially coated with cationic silylating reagents, poly(vinylsulfonate), and polybrene to form a custom designed surface that effectively inhibits adsorption of protein matrix on the capillary inner wall and allows for reproducible ion analysis. For the CE with capacitively coupled contactless conductivity detection, we used suitable background electrolytes (BGEs) for salivary ion analysis. Anions were separated using a mixture of 2-(N-morpholino)ethanesulfonic acid and l-arginine, and cations were separated using that with 18-crown-6. This setup enabled rapid separation, within 4 min, together with sensitive detection. We quantified nine common anions and five cations typically found in saliva samples using this CE method, both before and after a cold pressure test (CPT, a standard stress test). The CE system demonstrated consistent ion separation across 30 consecutive measurements without requiring capillary replacement. Notably, the salivary ion balance remained predominantly anion-rich, regardless of the CPT. Cold water exposure induced greater variation in the total anion concentration than in the total cation concentration. Further analysis using multiple regression analysis revealed strong relationships between nitrate and nitrite, formate and phosphate, and potassium and nitrate, before and after the CPT. Notably, potassium and nitrate ions exhibited variations in response to stress. These results provided a method for assessing salivary ion composition and insights into the potential of salivary ions as biomarkers for stress.

An effective preserving strategy for strawberries by constructing pectin/starch coatings reinforced with functionalized eggshell fillers

Food waste occurs frequently worldwide, though hunger and malnutrition issues have received global attention. Short-term spoilage of perishable foods causes a significant proportion of food waste. Developing simple, green, and low-cost strategies to preserve the freshness of perishable foods is important to address this issue and improving food safety. By using strawberries as the model perishable fruit, this study reported a pectin/carboxy methyl starch sodium (PC) based coating using epigallocatechin gallate-loaded eggshell powder (ES@EGCG) as the functional fillers. In comparison to PC coating, the PC-ES@EGCG coating displayed much-enhanced performance, such as enhanced mechanical (2 folds) and barrier (water vapor & oxygen) properties. This composite coating reduced the weight loss of strawberries from over 60% to around 30% after 7-day storage. Coated strawberries exhibit better freshness retention, which achieves the purpose of preserving strawberries during storage. This study provided a cost-effective and eco-friendly coating strategy for reducing food waste.

Breathable and wearable graphene/waterborne polyurethane coated regenerated polyethylene terephthalate fabrics for motion sensing and thermal therapy

The functional utilization of recycled polymers has emerged as a current prominent and timely subject. Flexible wearable devices with high sensitivity to conductivity have garnered significant attention in the fields of human healthcare monitoring and personal heat management. One significant obstacle that needs to be addressed is the simultaneous maintenance of both sensing functionality and durability in composite fabrics. In this paper, a collection of durable, breathable, and flexible smart fabric was produced using the scratch coating method. The fabrics were created by utilizing a regenerated polyethylene terephthalate fabric as a base material, incorporating graphene microsheets (G) as a conductive agent, and applying a waterborne polyurethane layer as a surface protective coating. Furthermore, an investigation was conducted to assess their sensing performance and electrothermal performance. The composite fabric exhibits significant advantages in terms of high conductivity (592 S/m), wide strain range, high sensitivity (Gauge factor = 6.04) and fantabulous dynamic stability (2000 cycles) at a mass ratio of Graphene/WPU loading of 8:2. These sensors were successfully utilized to monitor various degrees of real-time human body movements, ranging from significant deformation bending of elbows to slight deformation swallowing. Furthermore, the sensors also exhibit a significant electric heating effect. Specifically, when a voltage of 10 V is applied, the sensors can reach a steady state temperature of 53.3 °C within a mere 30 s. This discovery holds potential for the development of wearable heaters that can be used for on-demand thermal therapy, functional protective clothing, and medical electric heating wearables.

The Preservation Effect of Chitosan-hawthorn Leaf Extract Coating on Strawberries

Strawberries rapidly deteriorate postharvest, necessitating effective measures to extend their shelf life. This study focused on developing an eco-friendly chitosan-based protective film for strawberry preservation. Strawberries were treated with a coating solution containing varying concentrations of hawthorn leaf extract (HLE) (0.4%, 0.7%, and 1.0%), 1.5% chitosan (CH), and 1% acetic acid. The results demonstrated that coating strawberry fruit with 1% CH-HLE notably delayed fruit spoilage. In-depth analysis revealed that, compared with the uncoated strawberry fruits, the 1% CH-HLE coating effectively reduced weight loss, the respiration intensity, malondialdehyde (MDA) levels, and superoxide anion (O2·-) production. Additionally, the coated strawberries exhibited improved firmness, total soluble solids (TSS), vitamin C (Vc) content, titratable acidity (TA), and total phenolic compound (TPC) content. The enzyme activities of superoxide dismutase (SOD) and catalase (CAT) in the CH-HLE-coated strawberries were greater than those in their uncoated counterparts. The application of a 1% CH-HLE coating successfully delayed spoilage and extend the shelf life of the strawberries by approximately 4-5 days. These findings suggest that CH-HLE has significant potential as a resource for protecting fruits and vegetables, offering an environmentally sustainable solution for postharvest preservation.

Effect of EVA film and chitosan coating on quality and physicochemical characteristics of mango fruit during postharvest storage

Mango (Mangifera indica L.) is a major tropical fruit, but a short postharvest life hampers marketing. The objective of this work is to assess the influence of a novel nanocomposite poly (ethylene-co-vinyl acetate) (EVA) film and Chitosan (CTS) affect on mango postharvest quality while stored at 20 °C. The results showed that the film coating treatment reduced the decay rate and weight loss of mangoes, maintaining good postharvest quality of mango fruit. The film coating treatment increased the antioxidant capacity of mangoes by inhibiting PPO activity and increasing the activity of antioxidant enzymes. ACS, ACO, and ethylene release were all suppressed, as well as the expression of the ethylene receptors genes ETR1, ETR2, and ERS2, thus delaying mango aging. After harvest, the EVA treatment was superior to the CTS treatment in mango preservation.

Degradable chitosan-based bioplastic packaging: Design, preparation and applications

Food packaging is an essential part of food transportation, storage and preservation. Biodegradable biopolymers are a significant direction for the future development of food packaging materials. As a natural biological polysaccharide, chitosan has been widely concerned by researchers in the field of food packaging due to its excellent film-forming property, good antibacterial property and designability. Thus, the application research of chitosan-based food packaging films, coatings and aerogels has been greatly developed. In this review, recent advances on chitosan-based food packaging materials are summarized. Firstly, the development background of chitosan-based packaging materials was described, and then chitosan itself was introduced. In addition, the design, preparation and applications of films, coatings and aerogels in chitosan-based packaging for food preservation were discussed, and the advantages and disadvantages of each research in the development of chitosan-based packaging materials were analyzed. Finally, the application prospects, challenges and suggestions for solving the problems of chitosan-based packaging are summarized and prospected.

Techniques, applications and prospects of polysaccharide and protein based biopolymer coatings: A review

The growing relevance of sustainable materials has recently led to the exploration of naturally derived biopolymeric hydrogels as coating materials due to their biodegradability, biocompatibility, ease of fabrication and modification. Although many review articles exist on biopolymeric coatings, they mainly focus on a specific polysaccharide, protein biopolymer, or a particular application- biomedical engineering or food preservation. The current review first summarizes the commonly used polysaccharide and protein-based biopolymers like chitosan, alginate, carrageenan, pectin, cellulose, starch, pullulan, agarose and silk fibroin, gelatin, respectively, with a systematic description of the techniques widely used for physical coating on substrates. Then, broad applications of these biopolymeric coatings on various substrates in biomedical engineering- 3D scaffolds, biomedical implants, and nanoparticles are described in detail. It also entails the application of biopolymeric coatings for food preservation in the form of food packaging and edible coatings. A brief discussion on the newly discovered interest in exploring biopolymers for anticorrosive coating applications is also included. Finally, concluding remarks on the role of biopolymer microstructures in forming homogeneous coatings, prospective alternatives to the currently used biopolymers as coating material and the advent of computer-aided technologies to expedite experimental findings are presented.

Zigzag Hopping Site Embedded Covalent Organic Frameworks Coating for Zn Anode

Precise design and tuning of Zn hopping/transfer sites with deeper understanding of the dendrite-formation mechanism is vital in artificial anode protective coating for aqueous Zn-ion batteries (AZIBs). Here, we probe into the role of anode-coating interfaces by designing a series of anhydride-based covalent organic frameworks (i.e., PI-DP-COF and PI-DT-COF) with specifically designed zigzag hopping sites and zincophilic anhydride groups that can serve as desired platforms to investigate the related Zn2+ hopping/transfer behaviours as well as the interfacial interaction. Combining theoretical calculations with experiments, the ABC stacking models of these COFs endow the structures with specific zigzag sites along the 1D channel that can accelerate Zn2+ transfer kinetics, lower surface-energy, homogenize ion-distribution or electric-filed. Attributed to these superiorities, thus-obtained optimal PI-DT-COF cells offer excellent cycling lifespan in both symmetric-cell (2000 cycles at 60 mA cm-2) and full-cell (1600 cycles at 2 A g-1), outperforming almost all the reported porous crystalline materials.

Recent advances in starch-based coatings for the postharvest preservation of fruits and vegetables

Efficient and low-cost postharvest preservation of fruits and vegetables has always been one of the urgent problems to be solved in the food field. Due to the wide sources, good environmental and human safety, and high biodegradability, starch-based coating preservation method has great application prospects in the postharvest preservation of fruits and vegetables. However, starch materials also have the disadvantages of poor mechanical properties and easy water absorption performance, which makes it difficult to fully meet the requirements in practical production. Therefore, starch is often used in combination with other components to form composite materials. This paper began with an introduction to the preservation principles of edible starch-based coatings, including inherent properties and extra functional properties. Besides, the preservation principles of edible coatings and the recent advances in the field of fruit and vegetable preservation were also comprehensively reviewed, focusing on the preparation and application of starch-based coatings. The information will contribute to the further development of starch-based coatings to improve the postharvest preservation effect of fruits and vegetables.

Harmless pre-lithiation via advantageous surface reconstruction in sacrificial cathode additives for lithium-ion batteries

Sacrificial cathode additives have emerged as a tempting strategy to compensate the initial capacity loss (ICL) in Li-ion batteries (LIBs) manufacturing. However, the utilization of sacrificial cathode additives inevitably brings residuals, side reactions, and negative impacts in which relevant researches are still in the early stage. In this study, we conduct a systematic investigation on the effects of employing a nickel-based sacrificial additive, Li2Cu0.1Ni0.9O2 (LCNO), and propose a feasible strategy to achieve advantageous surface reconstruction on LCNO. Specifically, we build a Li5AlO4 (LAO) coating layer on the LCNO through dry ball milling and annealing treatment. This process not only consumes surface residual lithium compounds on LCNO but also demonstrates minimal detrimental effects on its performance. The surface reconstructed LCNO (SR-LCNO) reveals mitigated gas generation and suppressed structure degradation under high working voltage (＞4.1 V), thereby causing negligible negative effects on the cycling capability and rate performance of commercial cathode materials. The full cells containing SR-LCNO deliver significantly improved electrochemical properties, with no observed exacerbation of side reactions. This work awakes the awareness of the prudent utilization of sacrificial cathode additives and provides an effective strategy for harmless pre-lithiation via surface reconstructed sacrificial cathode additives.

Evaluation of the EMBOPIPE flow diverter device: in vivo and in vitro experiments

BACKGROUND

Although flow diverter device (FDD) has brought revolutionized advances in endovascular treatment of intracranial aneurysms, it also presents considerable drawbacks as well, as the innovation for novel device has never stopped. This preclinical research aims to evaluate the safety and efficacy of a newly developed FDD, the EMBOPIPE, through in vivo and in vitro experiments.

METHODS

Aneurysms were induced in 20 New Zealand white rabbits which were randomized to three follow-up groups according to the time elapsed after EMBOPIPE implantation (28, 90, and 180 days). Additional EMBOPIPEs were implanted in the abdominal aorta to cover the renal artery in nine rabbits. Angiography was performed immediately after device placement in all groups. Aneurysm occlusion, patency of renal arteries, and pathological outcomes were assessed. For the in vitro experiments, we measured the thrombogenic potential of EMBOPIPEs (n = 5) compared with bare stents (n = 5) using the Chandler loop model. Evaluation indicators were the platelet counts, macroscopic observations and scanning electron microscopy.

RESULTS

EMBOPIPEs were successfully deployed in 19 of 20 rabbit aneurysms (95.0%). The rates of complete or near-complete aneurysm occlusion were 73.3%, 83.3%, and 100% in the 28-, 90-, and 180-day groups, respectively. All renal arteries covered by EMBOPIPEs remained patent, and the mean difference in renal artery diameter before and after the device placement in the three groups was 0.07 mm, 0.10 mm, and 0.10 mm, respectively (p = 0.77). Renal pathology was normal in all cases. The pathological findings of the aneurysms were as follows: thickened and adequate neointimal coverage at the aneurysm neck, minimal inflammatory response, near-complete smooth muscle cell layer, and endothelialization along the device. In vitro experiments showed that the platelet counts were significantly higher in EMBOPIPE blood samples than in bare stent samples and that platelet adhesion to the device was lower in the EMBOPIPE stent struts compared with bare stent struts through macroscopic observations and scanning electron microscopy.

CONCLUSIONS

The EMBOPIPE can achieve high rates of aneurysm occlusion while maintaining excellent branch artery patency. It exhibited wonderful pathological results. This novel device with phosphorylcholine surface modification could reduce platelet thrombus attached to the stent struts.

A biodegradable PVA coating constructed on the surface of the implant for preventing bacterial colonization and biofilm formation

BACKGROUND

Bone implant infections pose a critical challenge in orthopedic surgery, often leading to implant failure. The potential of implant coatings to deter infections by hindering biofilm formation is promising. However, a shortage of cost-effective, efficient, and clinically suitable coatings persists. Polyvinyl alcohol (PVA), a prevalent biomaterial, possesses inherent hydrophilicity, offering potential antibacterial properties.

METHODS

This study investigates the PVA solution's capacity to shield implants from bacterial adhesion, suppress bacterial proliferation, and thwart biofilm development. PVA solutions at concentrations of 5%, 10%, 15%, and 20% were prepared. In vitro assessments evaluated PVA's ability to impede bacterial growth and biofilm formation. The interaction between PVA and mCherry-labeled Escherichia coli (E. coli) was scrutinized, along with PVA's therapeutic effects in a rat osteomyelitis model.

RESULTS

The PVA solution effectively restrained bacterial proliferation and biofilm formation on titanium implants. PVA solution had no substantial impact on the activity or osteogenic potential of MC3T3-E1 cells. Post-operatively, the PVA solution markedly reduced the number of Staphylococcus aureus and E. coli colonies surrounding the implant. Imaging and histological scores exhibited significant improvements 2 weeks post-operation. Additionally, no abnormalities were detected in the internal organs of PVA-treated rats.

CONCLUSIONS

PVA solution emerges as an economical, uncomplicated, and effective coating material for inhibiting bacterial replication and biofilm formation on implant surfaces, even in high-contamination surgical environments.

Preparation and characterizations of antibacterial iodine-containing coatings on pure Ti

Iodine-containing coatings were prepared on pure Ti surfaces via electrochemical deposition to enhance their antibacterial properties. The factors influencing iodine content were analyzed using an orthogonal experiment. The electrochemically deposited samples were characterized using scanning electron microscopy with energy dispersive spectroscopy and X-ray photoelectron spectroscopy, and their antibacterial properties and cytotoxicity were evaluated. The results showed that changing the deposition time is an effective way to control the iodine content. The iodine content, coating thickness, and adhesion of the samples increased with deposition time. Iodine in the coatings mainly exists in three forms, which are I2, I3-, and pentavalent iodine. For samples with iodine-containing coatings, the antibacterial ratios against E. coli and S. aureus were greater than 90% and increased with increasing iodine content. Although the samples with iodine-containing coatings showed some inhibition of the proliferation of MC3T3-E1 cells, the cell viabilities were all higher than 80%, suggesting that iodine-containing coatings are biosafe.

Innovative strategies for enhancing gas separation: Ionic liquid-coated PES membranes for improved CO2/N2 selectivity and permeance

As a cost-effective advancement in membrane technology, this study investigates the impact of PEG additive and CBT on the structural, stability, and gas permeance properties of PES-coated membranes, utilizing 1-dodecyl-3-methylimidazolium chloride ionic liquid ([DDMI][Cl] IL) as a carrier liquid. BET and FT-IR analyses highlight the significant enhancement in performance through the immobilization of pores with [DDMIM][Cl] IL. The investigation focuses on PES-M5-coated membranes, revealing excellent stability in finger-like pore structures prepared through direct immersion and nitrogen pressure immobilization. PES-M5-coated membranes with [DDMIM][Cl] IL via direct immersion experience lower weight loss than those coated using nitrogen pressure, with critical pressures at 1.4 and 1.25 bar, respectively. The study identifies PES-coated membranes, particularly PES-M25 (20.88 GPU) with macro-void pores and PES-M5 (29 GPU) with finger-like pores, exhibiting the highest CO2 permeance and CO2/N2 selectivity. As a cost-effective advancement in membrane technology, ionic liquids are employed in support membranes to enhance gas separation. Employing pure PES membranes with varying pore structures, created through the NIPS method, the study immobilizes [DDMI][Cl] IL in membrane pores through nitrogen pressure and direct immersion. Results underscore the successful application of porous support materials coated with ionic liquids for continuous CO2 and sulfur compound separation, showcasing competitive permeability and selectivity compared to traditional polymer membranes.

An in vitro pilot study investigating placenta-derived mesenchymal stem cell coating on polypropylene mesh materials

INTRODUCTION AND HYPOTHESIS

Polypropylene meshes (PM) used in pelvic organ prolapse surgery are being withdrawn from the market. Although concerns about the usage of PMs in stress incontinence surgery have been raised, it is still one of the best methods of curing stress urinary incontinence. With advancements in stem cell-based therapies, especially mesenchymal stem cells (MSCs), it is believed that coating the synthetic meshes with MSCs may minimize excessive tissue reactions ultimately leading to clinical problems such as pain, erosion or extrusion of the implanted material. In our study we tried to show the possibility of coating the PM with placenta-derived MSCs.

METHODS

Mesenchymal stem cells obtained from six placentas were isolated, cultured, and identified. MSCs were then soaked in either fibronectin or collagen prior to co-culturing with strips of PMs. One group is used as a control, and hence was not pretreated before co-culturing. Specimens were fixed and stained with both Gram and hematoxylin and eosin and marked with Vybran Dil and DAPI. All preparations were examined under a light microscope. The IMAGEJ program was utilized to determine the surface area of meshes coated with MSCs.

RESULTS

We clearly showed that PMs can be coated successfully with placenta-derived MSCs. The percentage of the coated area is significantly increased when meshes were pretreated with fibronectin or collagen (p<0.0001).

CONCLUSIONS

Placenta-derived MSCs can successfully coat PMs. The immunomodulatory properties of MSCs, which may be of great advantage in preventing the side effects of meshes, should be tested by in vivo and hopefully human studies before clinical applications.

Implants coating strategies for antibacterial treatment in fracture and defect models: A systematic review of animal studies

Objective

Fracture-related infection (FRI) remains a major concern in orthopaedic trauma. Functionalizing implants with antibacterial coatings are a promising strategy in mitigating FRI. Numerous implant coatings have been reported but the preventive and therapeutic effects vary. This systematic review aimed to provide a comprehensive overview of current implant coating strategies to prevent and treat FRI in animal fracture and bone defect models.

Methods

A literature search was performed in three databases: PubMed, Web of Science and Embase, with predetermined keywords and criteria up to 28 February 2023. Preclinical studies on implant coatings in animal fracture or defect models that assessed antibacterial and bone healing effects were included.

Results

A total of 14 studies were included in this systematic review, seven of which used fracture models and seven used defect models. Passive coatings with bacteria adhesion resistance were investigated in two studies. Active coatings with bactericidal effects were investigated in 12 studies, four of which used metal ions including Ag+ and Cu2+; five studies used antibiotics including chlorhexidine, tigecycline, vancomycin, and gentamicin sulfate; and the other three studies used natural antibacterial materials including chitosan, antimicrobial peptides, and lysostaphin. Overall, these implant coatings exhibited promising efficacy in antibacterial effects and bone formation.

Conclusion

Antibacterial coating strategies reduced bacterial infections in animal models and favored bone healing in vivo. Future studies of implant coatings should focus on optimal biocompatibility, antibacterial effects against multi-drug resistant bacteria and polymicrobial infections, and osseointegration and osteogenesis promotion especially in osteoporotic bone by constructing multi-functional coatings for FRI therapy.

The translational potential of this paper

The clinical treatment of FRI is complex and challenging. This review summarizes novel orthopaedic implant coating strategies applied to FRI in preclinical studies, and offers a perspective on the future development of orthopaedic implant coatings, which can potentially contribute to alternative strategies in clinical practice.

Advanced nanofibrous sorbents for the extraction of pollutants from river water and protein-containing matrices

The extraction efficiencies of thirty types of fibers produced by meltblown, alternating current electrospinning, and meltblown-co-electrospinning technologies were tested as advanced sorbents for on-line solid-phase extraction in a high-performance liquid chromatography system have been tested and compared with a commercial C18 sorbent. The properties of each fiber, which were often depended on the production process, and their applicability were demonstrated with the extraction of the model analytes nitrophenols and chlorophenols from various matrices including river water and to purify complex matrix human serum and bovine serum albumin from macromolecular ballast. Polycaprolactone fibers outperformed other polymers and were selected for subsequent modifications including (i) incorporation of hybrid carbon nanoparticles, i.e., graphene, activated carbon, and carbon black into the polymer prior to fiber fabrication, and (ii) surface modification by dip coating with polyhydroxy modifiers including graphene oxide, tannin, dopamine, hesperidin, and heparin. These novel fibrous sorbents were comparable to commercial C18 sorbent and provided excellent analyte recoveries of 70-112% even from the protein-containing matrices.

Failures analysis of tube coating in Circulating Fluidized Bed (CFB) boiler

Circulating Fluidized Bed (CFB) boiler often experience leaks in the wall tube due to corrosion and abrasion of the bed material after use that varies between 3 and 8 months. To avoid erosion corrosion, a coating was done in the form of Chrome Clad Tube Armor (CTA). In this research, a Failure Analysis (FA) was performed on the characterization of the boiler tube using several types of samples, which are Wall Tube Without Coating (WT) and CTA (in new condition and after eight months of use). Macro visual, Field emission scanning electron microscopes (FE-SEM), Fourier-transform infrared spectroscopy (FTIR), corrosion, and Thermogravimetric analysis (TGA) tests showed that the CTA type has better corrosion and thermal resistance. The hardness values of the CTA and WT coating substrates after eight months of use were 197.75 and 195.2 HV. The failure mechanism on the tube was caused by high temperatures (long-term overheating) and friction between the tube and the fluid or metal. Wall tubes in furnaces fail due to erosion and corrosion due to fluid and solid particle mixtures and environmental contact.

Research progress of metal biomaterials with potential applications as cardiovascular stents and their surface treatment methods to improve biocompatibility

Facing the growing issue of cardiovascular diseases, metallic materials with higher tensile strength and fatigue resistance play an important role in treating diseases. This review lists the advantages and drawbacks of commonly used medical metallic materials for vascular stents. To avoid post-procedural threats such as thrombosis and in-stent restenosis, surface treatments, and coating methods have been used to further improve the biocompatibility of these materials. Surface treatments including laser, plasma treatment, polishing, oxidization, and fluorination can improve biocompatibility by modifying the surface charges, surface morphology, and surface properties of the material. Coating methods based on polymer coatings, carbon-based coatings, and drug-functional coatings can regulate the surface properties, and also serve as an effective barrier to the interaction of metallic biomaterial surfaces with biomolecules, which can be used to improve corrosion resistance and stability, as well as improve their biocompatibility. Biocompatibility serves as the most fundamental property of cardiovascular stents, and maintaining the excellent and stable biocompatibility of cardiovascular stent surfaces is a current research bottleneck. Few reviews have been published on metallic biomaterials as cardiovascular stents and their surface treatments. For the purpose of advancing research on cardiovascular stents, common metal biomaterials, surface treatment methods, and coating methods to improve biocompatibility and comprehensive properties of the materials are described in this review. Finally, we suggest future directions for stent development, including continuously improving the durability and stability of permanent stents, accelerating the development of biodegradable stents, and strengthening feedback to improve the safety and reliability of cardiovascular stents.

Prediction of phase composition and mechanical properties Fe-Cr-C-B-Ti-Cu hardfacing alloys: Modeling and experimental Validations

Alloys of the Fe-Cr-C-B-Ti alloy system are characterized by brittleness, which can be eliminated by the copper alloy, while corrosion resistance and abrasive wear resistance are significantly reduced. In this article, comprehensive investigations are carried out on the microstructure and mechanical properties of the proposed high-copper boron-containing alloy 110Cr4Cu7Ti1VB. Systematic theoretical and experimental studies encompassed thermodynamic calculations in ThermoCALC, production of flux-cored wires for hardfacing and welding, receipt of SEM images, acquisition of load and unload diagrams (discharge) via instrumental indentation on various phases of the deposited metal, and determination of chemical composition at indentation points through local chemical analysis. Mechanical properties of some phases such as γ-Fe phase (austenite), hemioboride Fe2(В,С) and boron cementite Fe3(В,С) and titanium carbide TiC in Fe-Cr-C-B-Ti-Сг alloy were determined by using density functional theory (DFT) implemented in the CASTEP code. We also compared these compounds; properties with other available commercial compounds, where available. With the knowledge of calculated elastic constants, the moduli, the Pugh's modulus ratio G/B, the Poisson's ratio v and the hardness of the title phases, 110Cr4Cu7Ti1VB were further predicted and discussed.

Use of Aureobasidium in a sustainable economy

Aureobasidium is omnipresent and can be isolated from air, water bodies, soil, wood, and other plant materials, as well as inorganic materials such as rocks and marble. A total of 32 species of this fungal genus have been identified at the level of DNA, of which Aureobasidium pullulans is best known. Aureobasidium is of interest for a sustainable economy because it can be used to produce a wide variety of compounds, including enzymes, polysaccharides, and biosurfactants. Moreover, it can be used to promote plant growth and protect wood and crops. To this end, Aureobasidium cells adhere to wood or plants by producing extracellular polysaccharides, thereby forming a biofilm. This biofilm provides a sustainable alternative to petrol-based coatings and toxic chemicals. This and the fact that Aureobasidium biofilms have the potential of self-repair make them a potential engineered living material avant la lettre. KEY POINTS: •Aureobasidium produces products of interest to the industry •Aureobasidium can stimulate plant growth and protect crops •Biofinish of A. pullulans is a sustainable alternative to petrol-based coatings •Aureobasidium biofilms have the potential to function as engineered living materials.

Integrating experimental and theoretical studies in the development of a novel alginate-based bio-composite for copper anticorrosion in 3.5 % NaCl environments

The development of new coatings based on a biopolymer, epichlorohydrin-modified alginate, and alginate-epichlorohydrin-SrTiO3 nanocomposites incorporating SrTiO3 (STO) nanoparticles in the alginate (Alg) matrix (Alg-Ep-STO), has been addressed in this study. Various characterization techniques were employed to analyze the prepared compounds, including X-ray diffraction spectroscopy (XRD), Fourier-transform infrared spectroscopy (FTIR), as well as surface analysis methods such as Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX). Furthermore, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarisation (PDP) methods were used to evaluate corrosion inhibition and protection durability. The results demonstrate that the incorporation of STO nanoparticles into the alginate matrix with epichlorohydrin significantly improved the metal's resistance to corrosion. The experimental findings received reinforcement from various computational methods, including density functional theory (DFT), Molecular Dynamics (MD) and Monte Carlo (MC) simulations, which were employed to investigate the interactions between the Alg-Ep-STO nanocomposite and the copper surface. The computational outcomes revealed that the Alg-Ep-STO nanocomposite exhibits robust adhesion to the copper surface, maintaining a flat orientation, with its alignment being notably influenced by the presence of STO nanoparticles.

Bioactive apatite-wollastonite glass ceramics coating on metallic titanium for biomedical applications: effect of boron

Metallic titanium (Ti) implant surfaces need improvement for bioproperties and antibacterial behavior. For this purpose, a new boron-doped bioactive apatite-wollastonite (AW) coating was successfully developed on the Ti plate surface. The effects of boron addition on the microstructure, mechanical properties, and bioproperties of the AW coating were investigated. With the addition of boron (B), the AW coating morphology became less porous and compact. In terms of bio properties, the rate of apatite formation increased with the addition of B, and the cell viability rate increased from approximately 66-81%. B addition increased the elastic modulus of the AW coating from about 24-46 GPa and increased its hardness about 2.5 times. In addition, while no antibacterial activity was observed in the AW coating, the addition of boron slightly introduced antibacterial properties. The novel AW/B composite coating obtained is promising for Ti implant surfaces.

Natural deep eutectic solvents (NADES)-Extracted Anthocyanins: Bioaccessibility in electrospun PEO microfibers

Anthocyanins extracted with deep eutectic solvent (NADES) (chlorine-chloride: xylitol, 5:2) were used to produce polyethylene oxide (PEO) composites through electrospinning technique, analyzing their microscopic and physical characteristics. The coated anthocyanins were then subjected to in vitro gastrointestinal digestion to evaluate their bioaccessibility compared to lyophilized jussara pulp. The remaining total anthocyanin content (TAC) after intestinal in vitro digestion did not change significantly among the assessed samples, and both showed around 30% recovery. The TAC recovery after the gastric phase, on the other hand, showed a major difference (70.84% vs. 48.13%), revealing that the composites fabricated by the electrospinning technique can significantly maintain anthocyanins NADES-extracted stability during the gastric phase of digestion, potentially allowing better absorption trough stomach wall. The results can be considered a first step to applying anthocyanins-encapsulated in foodstuff as a natural pigment.

Impact of nanoscale silicon dioxide coating of stainless-steel surfaces on Listeria monocytogenes

High resistance to environmental factors as well as the ability to form biofilms allow Listeria monocytogenes to persist for a long time in difficult-to-reach places in food-producing plants. L. monocytogenes enters final products from contaminated surfaces in different areas of plants and poses a health risk to consumer. Modified surfaces are already used in the food industry to prevent cross-contamination. In this study, stainless-steel surfaces were coated with nanoscale silicon dioxide and the effects on attachment, bacterial growth and detachment of L. monocytogenes were evaluated. Attachment was considered for three different ways of application to simulate different scenarios of contamination. Bacterial growth of L. monocytogenes on the surface was recorded over a period of up to 8 h. Detachment was tested after cleaning inoculated stainless-steel surfaces with heated distilled water or detergent. Coating stainless-steel surfaces with nanoscale silica tends to reduce adherence and increased detachment and does not influence the bacterial growth of L. monocytogenes. Further modifications of the coating are necessary for a targeted use in the reduction of L. monocytogenes in food-processing plants.

Study on mechanism of cellulose nanocrystals on hydrophobic phthalocyanine green in aqueous phase

Phthalocyanine green is a hydrophobic pigment with excellent properties, which is usually dispersed in the organic phase. However, most organic phases are volatile and harmful to the environment and organisms. Therefore, phthalocyanine green dispersed in the aqueous phase has development potential. In this work, cellulose nanocrystals (CNCs) were used as dispersant and stabilizer to disperse phthalocyanine green in the aqueous phase. Phthalocyanine green was added to CNCs colloid to prepare phthalocyanine green suspensions with good dispersibility and stability. The particle size, zeta potential, absorbance and microstructure of the phthalocyanine green suspensions were tested and analyzed. The results showed that CNCs had good dispersibility and stability to phthalocyanine green due to charge repulsion and steric hindrance. The phthalocyanine green suspensions were nano-sized and had well compatibility with different types of coating forming substances. The coatings of the mixture had good water resistance, adhesion and mechanical properties. The suspensions had the application property and could be mixed with coating forming substances to prepare coating materials. As a renewable and easily degraded biomass resource, CNCs are expected to become a new dispersant and stabilizer for pigment.

Performance of graphene oxide as a water-repellent coating nanomaterial to extend the service life of concrete structures

Surface treatments help to protect the built heritage against damage (environmental, accidental, etc.), reducing repair and restitution costs and increasing the useful life of building materials. The use of nanomaterials is currently the most important field of research in surface treatment technology for the preservation of building materials and, more specifically, to improve their durability and prevent their deterioration, extending their useful life. This paper studies the influence of a graphene oxide (GO) suspension as a surface treatment on the properties of concrete. The results indicate that, at best, surface treatment with GO can decrease both the water absorption and capillary absorption of concrete by about 15 %. The increase in the amount of GO deposited as a surface treatment leads to a further reduction in concrete water absorption. It is shown that, at best, GO coating also reduces water penetration at low and high pressures by approximately 20 % and 60 %, respectively. In addition, scanning electron microscopy analysis shows that GO surface treatment facilitates the hydration process and densifies the concrete microstructure. A simple aqueous suspension of GO is revealed as a tool with a high potential to protect concrete surfaces in a fast and cost-effective way, thanks to the easy application by spraying and the small amount of material needed to obtain great results.

Interfacial Activity of Janus Particle: Unity of Molecular Surfactant and Homogeneous Particle

Janus particles with different compositions and properties segmented to different regions on the surface of one objector provide more opportunities for interfacial engineering. As a novel interfacial active material, Janus particles integrate the amphiphilic properties of molecular surfactants and the Pickering effect of homogeneous particles. In this research, the outstanding properties of Janus particles on various interfaces are examined from both theoretical and practical perspectives, and the advantages of Janus particles over molecular surfactants and homogeneous particle surfactants are analyzed. We believe that Janus particles are ideal tools for interface regulation and functionalization in the future.

Nanocoating and its application as antimicrobials in the food industry: A review

Nanocoatings are ultra-thin layers on the nanoscale (<100 nm) that are deposited on the substrate to improve their properties and functionality. These nanocoatings provide significant advantages compared to traditional coating, including stain resistance, antimicrobial and antioxidant activities, odor control and delivery of active agents, and liquid repellence properties. In the food industry, nanocoating is widely used in the food packaging sector. In this regard, nanocoating offers antimicrobials and antioxidant properties to active food packaging by incorporating active bioactive compounds into materials used in already existing packaging. The application of nanocoating is applied to these kinds of food packaging with nano coating to improve shelf life, safety, and quality of food packaging. In smart/intelligent packaging, the active packaging coating is promising food packaging, which is designed by releasing preservatives and nanocoating as an antimicrobial, antifungal, antioxidant, barrier coating, and self-cleaning food contact surfaces. In addition, nanocoating can be used for food contact surfaces, kitchen utensils, and food processing equipment to create antimicrobial, antireflective, and dirt-repellent properties. These are critical properties for food processing, especially for meat and dairy processing facilities, which can reduce biofilm formation and prevent cross-contamination. Recently, appreciable growth in the development of the application of nanocoating as edible films for coating food products has emerged to improve food safety issues. In this regard, much scientific research in the area of nanocoating fruits and vegetables, and other food products was performed to address food safety issues. Hence, this promising technology can be a great addition to the agricultural and food industries. Thus, this review addresses the most relevant information about this technology and the applications of nanocoating in the food industry.

Polysaccharide-based hydrogels for medical devices, implants and tissue engineering: A review

Hydrogels are highly biocompatible biomaterials composed of crosslinked three-dimensional networks of hydrophilic polymers. Owing to their natural origin, polysaccharide-based hydrogels (PBHs) possess low toxicity, high biocompatibility and demonstrate in vivo biodegradability, making them great candidates for use in various biomedical devices, implants, and tissue engineering. In addition, many polysaccharides also show additional biological activities such as antimicrobial, anticoagulant, antioxidant, immunomodulatory, hemostatic, and anti-inflammatory, which can provide additional therapeutic benefits. The porous nature of PBHs allows for the immobilization of antibodies, aptamers, enzymes and other molecules on their surface, or within their matrix, potentiating their use in biosensor devices. Specific polysaccharides can be used to produce transparent hydrogels, which have been used widely to fabricate ocular implants. The ability of PBHs to encapsulate drugs and other actives has been utilized for making neural implants and coatings for cardiovascular devices (stents, pacemakers and venous catheters) and urinary catheters. Their high water-absorption capacity has been exploited to make superabsorbent diapers and sanitary napkins. The barrier property and mechanical strength of PBHs has been used to develop gels and films as anti-adhesive formulations for the prevention of post-operative adhesion. Finally, by virtue of their ability to mimic various body tissues, they have been explored as scaffolds and bio-inks for tissue engineering of a wide variety of organs. These applications have been described in detail, in this review.

Physical stability, microstructure and antimicrobial properties of konjac glucomannan coatings enriched with Litsea cubeba essential oil nanoemulsion and its effect on citruses preservation

This study purposed to develop konjac glucomannan (KGM) based antimicrobial coatings containing Litsea cubeba essential oil nanoemulsion (LNE) for citruses preservation. Physical stability, rheological, structural and antimicrobial properties of the coating solutions were investigated, along with the release characteristics of Litsea cubeba essential oil (LCO). Results showed that the coating solutions displayed shear thinning behavior. The oil droplets were distributed homogeneously in KGM phase with good stability. The coating structure became loose with increasing LNE content due to LNE interfering with molecular interactions and entanglement of KGM. The coating solutions showed stronger antibacterial activity against Escherichia coli than against Staphylococcus aureus and were effective in inhibiting the growth of Penicillium italicum on citrus surfaces. KGM-LNE 10 negatively affected citruses due to phytotoxicity caused by high levels of LCO. LCO was released slowly and continuously from the coatings, and its release was faster in deionized water than in an ethanol-water solution. KGM-LNE 2.5 coated citruses had the least weight loss, the greatest hardness, and kept the minimum changes in total soluble solids, total acid and vitamin C content, implying that KGM-LNE 2.5 best maintained the quality of citruses. The findings suggest that KGM-based coatings containing LNE have high potential for citruses preservation.

Effect of coating with combined chitosan and gallic acid on shelf-life stability of Jeju black cattle beef

OBJECTIVE

Beef of Jeju black cattle (JBC) is considered as a healthy meat type due to its significantly higher unsaturated fatty acids (UFA). Lipid (e.g., UFA) is highly susceptible to oxidizing agents, which results in the quality deterioration and economic value loss of meat products. Therefore, development and application of novel preservative techniques is necessary to improve the shelf-life stability of high-UFA beef. The objective of this study was to assess the applicability of chitosan-based coatings in preservation of JBC beef.

METHODS

Different coating solutions: 2% chitosan alone, and 2% chitosan containing 0.1% or 0.3% gallic acid were prepared to investigate their applicability in preservation of fresh beef during storage. Jeju black cattle beef (2-cm thick steaks) were non-coated (control) or coated with the above coating solutions, placed on trays, over-wrapped with plastic film and stored at 4°C. The microbiological indices, color, total volatile basic nitrogen (TVBN) and lipid oxidation of the beef were investigated after 1, 10, and 21 days of storage.

RESULTS

Coating with 2% chitosan alone reduced the spoilage bacteria count, TVBN and thiobarbituric acid reactive substances levels in the beef compared with control during storage (p<0.05). Noticeably, coating with 2% chitosan containing 0.1% or 0.3% gallic acid was more effective on retardation of spoilage bacteria growth, lipid oxidation and discoloration in the beef compared to the chitosan coating alone over the storage period (21 days) (p<0.05).

CONCLUSION

Taken together, the combined chitosan and gallic acid coating could be used as a bio-preservative technique in the meat industry.

Advancements in coating technologies: Unveiling the potential of chitosan for the preservation of fruits and vegetables

Post-harvest losses of fruits and vegetables pose a significant challenge to the agriculture industry worldwide. To address this issue, researchers have turned to natural and eco-friendly solutions such as chitosan coatings. Chitosan, a biopolymer derived from chitin, has gained considerable attention due to its unique properties such as non-toxicity, biodegradability, biocompatibility and potential applications in post-harvest preservation. This review article provides an in-depth analysis of the current state of research on chitosan coatings for the preservation of fruits and vegetables. Moreover, it highlights the advantages of using chitosan coatings, including its antimicrobial, antifungal, and antioxidant properties, as well as its ability to enhance shelf-life and maintain the quality attributes of fresh product. Furthermore, the review discusses the mechanisms by which chitosan interacts with fruits and vegetables, elucidating its antimicrobial activity, modified gas permeability, enhanced physical barrier and induction of host defense responses. It also examines the factors influencing the effectiveness of chitosan coatings, such as concentration, molecular weight, deacetylation degree, pH, temperature, and application methods.

Comparative Evaluation of Wear Strength and Compressive Strength of Two Pit and Fissure Sealants with a Nanofilled Resin Coating: An In Vitro Study

Introduction

The role of sealants for pits and fissures has been emphasized in caries prevention. Considering the advantages of a surface sealer and the effects of its application over restorative materials; the study is aimed at evaluating two pit and fissure sealants with a nanofilled resin coating.

Materials and methods

In this in vitro double-blinded study, a total of 60 caries-free extracted third molars were collected and divided into two groups of 30 each receiving either a resin-based sealant (Helioseal F) or a glass ionomer-based sealant (GC Fuji VII). Each sample was then applied with GCoat Plus surface sealer. 15 samples each containing GC Fuji VII and 15 containing Helioseal F were then subjected to wear. Another 15 samples of GC Fuji VII and 15 of Helioseal F were subjected to compressive load.

Results

On assessing the wear strength, the weight loss in group I (resin sealant with surface sealer) was 1.73 ± 0.50 (μg) which was statistically significant (p = 0.023). There was no significant difference in comparing the wear depth between both groups. There was a high statistically significant difference when assessing the compressive strength, group II (glass ionomer sealant with surface sealer) had 3566.4 ± 757 (μm) when compared to group I (resin sealant with surface sealer) 1568.53 ± 680 (p ≤ 0.01).

Conclusion

Sealants are known for their poor retention and keeping that in mind we designed this study to evaluate the physical properties of sealants with a resin coating over them. Within the limitations of this study, the conclusions are glass ionomer sealant showed greater resistance to wear when compared to the resin-based sealant and the resin-based sealant showed higher compressive strength values than the glass ionomer sealant.

How to cite this article

Gunasekaran R, Sharmin D, Baghkomeh PN, et al. Comparative Evaluation of Wear Strength and Compressive Strength of Two Pit and Fissure Sealants with a Nanofilled Resin Coating: An In Vitro Study. Int J Clin Pediatr Dent 2024;17(1):31-35.

Sonocatalytic induced dye degradation and antibacterial performance of SrTiO3 nanoparticles embedded cotton fabric

In the present work, a pigment paste was prepared by adding strontium titanate (SrTiO3) nanoparticles (NPs) particles to a water and adhesive binder paste. Screen printing was utilized to embed the cotton fabric with the prepared pigment paste. Sonocatalytic induced antibacterial and dye mineralization abilities were evaluated for the printed fabric. The produced samples were examined for efficacy against the pathogens E. coli and S. aureus. The prepared SrTiO3 embedded cotton fabric inhibited (after 2 h) E. coli and S. aureus by 99.3% and 96.09%, respectively. The coated fabric was able to reduce pathogens by more than 92% even after 15 washing cycles. The Rhodamine B (RhB) dye was mineralized by 53% in 210 min by STO printed fabric as opposed to about 8% by pristine cotton. The results revealed that the intrinsic properties of cotton including tensile, abrasion, and air permeability remained unaffected by the printing of STO-NPs onto fabric.

STAR® total ankle replacements with BONIT® coating: A prospective 2-17 year follow-up study of 474 ankles from a single center

BACKGROUND

Different coatings of the metal implants of STAR prostheses have been used since 1999. In Europe metal implants with a double calcium-phosphate coating (BONIT) on a titanium sprayed surface have been available since 1999.

METHODS

We present a 2-17 year follow-up of a consecutive series from a single center with 474 STAR ankle replacements where the BONIT type of coating has been used.

RESULTS

55 prostheses (12%) have been revised, the majority of them due to fracture of the mobile bearing. 22 prostheses (5%) have been converted to an arthrodesis. Analysis of survival of the specific components showed an estimated 10-year survival rate of the tibia component, talus component and polyethylene mobile bearing of 99%, 98% and 84%, respectively. The corresponding estimated 15-year survival was 98%, 98% and 74%, respectively.

CONCLUSION

This study showed an extraordinary high survival rate of the metal implants.

LEVEL OF EVIDENCE

Level III, prospective cohort series.

Effects of preharvest chitosan-Myrtus communis essential oil composite and postharvest nanocellulose on quality of strawberry

The objective of this study was to investigate the effects of preharvest chitosan-Myrtus communis essential oil composite (1.5 and 3.0 %) and postharvest nanocellulose (0.3 and 0.6 %) on the quality of strawberries. The gas chromatography-mass spectrometry (GC/MS) analysis led to identification of 32 compounds in the Myrtus communis essential oil. The study showed that using CHS-ES composite coating for foliar application could increase the lifespan of the fruit by up to 24 days. This is because it increases the levels of components, such as phenol content (TPC) total flavonoids content (TFC) vitamin C, firmness and SSC. It also enhances the effectiveness of enzymes such, as glutathione peroxidase (GSH POD) and polyphenol oxidase (PPO). The use of CHS-ES treatments reduced the weight loss of fruits between 50 and 80 %, which is very important from the commercial point of view and maintaining nutritional properties, marketability and appearance. The microscopic analysis further revealed that using CHS-ES composite + nanocellulose coating produced a more continuous and uniform surface than the control. In general, this method is both safe and environmentally friendly while also proving to be effective, in preserving and enhancing the quality of strawberries.

Crosslinked carboxymethyl cellulose colloidal solution for cotton thread coating in wound dressing: A rheological study

Cotton thread therapeutic properties as a wound dressing can be enhanced by utilising carboxymethyl cellulose-nanoparticles (CMC/NPs) colloidal solution as a coating solution. Nanoparticles such as graphene oxide (GO), graphene quantum dots (GQD), and silver nanoparticles (AgNP) stability in CMC was investigated through the rheological analysis and UV-Vis spectroscopy of the colloidal solutions. Citric acid (CA) acted as a crosslinker and was utilised to crosslink the colloidal solution with cotton thread. These CMC/NPs coated threads were subjected to mechanical properties and antibacterial activity analysis. Results obtained indicate less nanoparticle agglomeration and were stable in the CMC-based nanofluid. CMC/NPs rheological study suggested that colloidal solutions exhibited shear thinning behaviour and behaved as non-Newtonian fluids with n < 1. Crosslinked CMC/NPs appeared in a gel-like state as the viscoelasticity of the solution increased. Among the colloidal solutions, CMC/AgNP showed the highest enhancement with a significant difference at p < 0.05 in terms of mechanical and antibacterial properties. Consequently, the rheological properties and stability of CMC/NPs might influence the coating solution's appearance and refine the cotton thread's microstructure for a functional wound dressing to be further utilised as a coating solution for antibacterial cotton thread wound dressing material.

Synthesis, optimization via response surface methodology, and structural properties of carboxymethylcellulose/curcumin/graphene oxide biocomposite films/coatings for the shelf-life extension of shrimp

In this study, carboxymethylcellulose (CMC), curcumin (Cur), and graphene oxide (GO) were used to prepare a novel biocomposite film (CMC-Cur-GO). A central composite design under response surface methodology was employed to optimize the films in terms of water vapor permeability (WVP) and swelling percentage (SP). Under the optimum conditions, which the rates of CMC, GO and curcumin were found to be 1350 mg, 29.99 mg, and 0.302 g, respectively, WVP and SP of CMC-Cur-GO were obtained 0.902 × 10-8 (g/m·h·Pa) and 13.62 %, respectively. The biocomposite films (CMC, CMC-Cur, CMC-GO and CMC-Cur-GO) were characterized by Fourier transform infrared spectroscopy, field-emission scanning electron microscope, thermal gravimetric analysis, X-ray diffraction analysis, ultraviolet-vis light transmittance, moisture content, and mechanical properties. Compared with pure CMC film, the tensile strength, elongation at break and Young's modulus of CMC-Cur-GO were significantly improved by up to 75 %, 41 % and 23 %, respectively (p < 0.05). Then, CMC-Cur-GO was applied as a coating solution for the shrimps. The coated shrimps with the CMC-Cur-GO significantly (p < 0.05) showed a noteworthy improvement in microbial quality (total and psychrotrophic bacterial count), chemical deterioration and lipid oxidation (pH and total volatile basic nitrogen, peroxide value and thiobarbituric acid) and physical characteristic (weight loss) as compared to other samples. The CMC-Cur-GO coating could increase the shelf life of shrimp under refrigerated storage.

Effect of chitosan-based bio coating on mechanical, structural and physical characteristics of microfiber based paper packaging: An alternative to wood pulp/plastic packaging

Limnocharis flava is a noxious aquatic weed that poses a threat to paddy cultivation. The high cellulose and low lignin contents in this plant make it a potential raw material for papermaking. Against this backdrop, this study was taken up to develop Limnocharis flava (LF) based sheets containing natural fibres from Banana (B), Pineapple (P), and Rice Straw (RS) as reinforcing agents. The influence of carboxymethyl cellulose (CMC) as a binder on the LF-based sheets was also studied. To enhance the mechanical and moisture resistance properties, a chitosan coating was provided to the sheets. Analytical tests for mechanical properties, water barrier properties, functional groups, structure and microstructure, thermal properties and biodegradability were performed. Among the samples, LF + B showed the highest tensile strength (34.86 Mpa) and bursting strength (13.055 kg/cm2), while LF + R had higher puncture and tearing strengths. Chitosan coating was found to enhance the sheets and improve the water barrier properties mechanically. The contact angle of LF + B increased from 91.6° to 110.65°, while the water vapour transmission rate of LF reduced from 532.18 to 404.47 on providing chitosan coating. The significant interactions of reinforcing agents were confirmed by the results of FTIR and that of the coating by the SEM micrographs. The LF-based sheets were also found to have decent thermal stability. The high value of the crystallinity index in LF + R samples supported their remarkable mechanical properties. This study proclaims the notable suitability of Limnocharis flava in manufacturing paper for packaging applications.

Antimicrobial mechanism of cuprous oxide (Cu2O) coatings

Some very effective antimicrobial coatings exploit copper or cuprous oxide (Cu2O) as the active agent. The aim of this study is to determine which species is the active antimicrobial - dissolved ions, the Cu2O solid, or reactive oxygen species. Copper ions were leached from Cu2O into various solutions and the leachate tested for both dissolved copper and the efficacy in killing Pseudomonas aeruginosa. The concentration of copper species leached from Cu2O into aqueous solution varied greatly with the composition of the aqueous solution. For a range of solution buffers, killing of P. aeruginosa was highly correlated with the concentration of copper in the leachate. Further, 10 µL bacterial suspension droplets were placed on Cu2O coatings, with or without a polymer barrier layer, and tested for bacterial kill. Killing occurred without contact between bacterium and solid, demonstrating that contact with Cu2O is not necessary. We therefore conclude that soluble copper species are the antimicrobial agent, and that the most potent species is Cu+. The solid quickly raises and sustains the concentration of soluble copper species near the bacterium. Killing via soluble copper ions rather than contact should allow copper coatings to kill bacteria even when fouled, which is an important practical consideration.

Fabrication of MnO2 coating on aluminum honeycomb for fast catalytic decomposition of ozone at room temperature

Herein, the coating of MnO2 nanomaterials on the surface of aluminum honeycomb was carried out to meet the requirements of high air velocity, low pressure drop and high activity in ozone removal scenarios. A commercially readily available waterborne silica sol mixed with waterborne acrylate latex was creatively utilized as the binder. A series of coating samples were prepared by spray coating method and evaluated focusing on their adhesion strength and catalytic activity towards ozone decomposition in an air duct at room temperature, by varying MnO2/binder mass ratio and number of sprayings. It was found that the adhesion strength of the catalytic coatings on the aluminum honeycomb increased with the increase of binder mass ratio, but the increased binder made the catalyst particles closely packed, resulting in reduced exposure of active sites and decrease of ozone conversion. Accordingly, catalyst slurry with 81.8 wt.% MnO2 in dry coating and spraying times of two were determined as the optimal process parameters. As-prepared aluminum honeycomb filter with MnO2 layer of 50 µm thickness achieved ozone conversion of 29.3%±1.7% under conditions of air velocity 3.0 m/sec, relative humidity ∼50%, room temperature (26°C) and initial ozone concentration of 200 ppbV. This filter can be well adaptable to indoor air purification equipment operating at high air velocity with low wind resistance.

Development of mussel-inspired chitosan-derived edible coating for fruit preservation

Fruit rotting at the postharvest stage severely limits their marketing supply chains and shelf-life. Thus, developing a green and cost-effective approach to extend the shelf-life of perishable foods is highly desired. In this study, inspired by the mussel-adhesion strategy, a multifunctional fruit coating material has been developed using a quaternized catechol-functionalized chitosan (CQ-CS) grafted with 2, 3-epoxypropyl trimethyl ammonium chloride and 3, 4-dihydroxy benzaldehyde. The as-prepared CQ-CS coating exhibited excellent mechanical properties, universal surface adhesion abilities, antimicrobial and antioxidant capacities without any potential toxicity effects. Using strawberry and banana as model fruits, we showed that the CQ-CS coating could effectively maintain the fruit's firmness and color, decrease the weight loss rate, and prevent microbial growth, thus finally extending their shelf- life when compared to uncoated samples, indicating the universal application of the as-prepared CQ-CS coating. These findings demonstrated that this novel conformal coating of CQ-CS has great potential for fruit preservation in the food industry.

Novel surface-treatment for bottom ash from municipal solid waste incineration to reduce the heavy metals leachability for a sustainable environment

Unconventional treatments can provide a modification to convert ash waste into valuable materials that can be used in various applications. This study focuses on bottom ash (BA) collected from a local incineration plant and characterizes its chemical composition before and after pretreatment by coating with polymers. The toxicity-characteristic leaching procedure (TCLP) was used to identify selected heavy metal leaching after treatment with vinyl-terminated polydimethylsiloxane (PDMS) of different molecular weights. BA coatings were incorporated in two ratios, 0.5% and 1%, by milling to avoid heavy metal leaching. The results showed that all the coating batches had reduced concentrations of copper (Cu), manganese (Mn), and zinc (Zn), whereas the concentrations of chromium (Cr) and cadmium (Cd) showed higher amounts of BAV34 (0.5%) and BAV25 (1%). The treated BA with GP demonstrated percentages of reduction of 70%, 65%, 80%, 75%, 90%, and 80% for Cu, Mn, Ni, Zn, Pb, and Cd, respectively. The milling procedure reduced the particle size of the coated ash. Hydrophobicity was observed in all coating batches compared to untreated BA. The thermogravimetric analysis (TGA) results showed variations between BA and treated BA, which confirmed that PDMS caused surface modification. These features have potential significance for extending the use of coated ash as a sustainable material for construction applications.

Surface modification of FeⅢ-juglone coating on nanofiltration membranes for efficient biofouling mitigation

Nanofiltration membranes have increasingly played a vital role in the purification of surface water and the recycling of wastewater. However, the problem of membrane biofouling, which leads to shortened service life and increased energy consumption, has hindered the widespread application of nanofiltration membranes. In this study, we developed functionalized nanofiltration membranes with anti-adhesive and anti-biofouling properties by coordinating FeIII and juglone onto commercial nanofiltration membranes in a facile and viable manner. Due to the hydrophilic nature of the FeⅢ-juglone coating as well as its ultra-thin thickness and minimal impact on the membrane pores, the permeance of the optimally modified membrane even increased slightly (14 %). The outstanding anti-adhesive property of the FeⅢ-juglone coating was demonstrated by a significant reduction in the adsorption of proteins and bacteria. Furthermore, the modified membranes exhibited lower flux decline amplitude and reduced biofilm deposition during dynamic fouling experiment, further supporting the outstanding anti-biofouling performance of the nanofiltration membrane after the modification with FeⅢ-juglone coating. This study presents a novel and feasible approach for simultaneously improving the water permeance, anti-adhesive property and anti-biofouling property of commercial nanofiltration membranes.

Evaluation of the quality features of electrospray-coated pineapple slices with pomegranate and grape seed oil-enriched emulsions

The quality characteristics of pineapple slices coated with emulsions enriched with pomegranate seed oil (PSO) and grape seed oil (GSO) by electrospray coating (ESC) and dip-coating (DC) methods were investigated. The ESC method was evaluated as an alternative to conventional DC. Pineapple slices were stored in clear polystyrene cups for seven days at 5 °C and 80% RH. The weight loss (%), pH, titratable acidity, color, firmness, total antioxidant activity (TAA), total phenolic content (TPC), microbiological, and sensory qualities of fresh-cut pineapple slices were evaluated. Coated samples had significantly lower weight loss values than the non-coated samples after 7 days of storage. The usage of GSO-enriched emulsion with the ESC method was found to be more successful in preserving the titratable acidity. Although all the samples exhibited a significant decrease in yellowness (b*), the electrospray-coated pineapple slices had the highest. Incorporating GSO into the emulsions helped protect the tissue of the fresh-cut pineapples, regardless of the coating method used. The TPC and TAA values of the samples coated by the ESC method with emulsions enriched with PSO showed a lower decrease compared to other treatments. It was determined that the ESC method was more successful in preserving the sensory qualities of fresh-cut pineapples. These findings suggested that using ESC as a coating method with EO-enriched emulsions has positive effects on the quality features of fresh-cut pineapples.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-023-05839-4.

A practical green synthesis method of Ag NPs using rosy periwinkle plant leaves for solar panel coating

Coated silver nanoparticles (Ag NPs) are currently receiving interest because of their numerous uses in various fields of electronics, antimicrobials, manufacturing sectors, optical science, and pharmaceuticals. Among others, it gained significant attention in the power electronic system. The goal of the proposed study is to use a cost-effective coating material for solar panels; to accomplish this, silver nanoparticles were synthesized from the leaves of the Rosy Periwinkle plants. Green synthesis and characterization, such as Ultraviolet Visible Spectrometer (UV-Vis) analysis, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), and Fourier Transform Infrared Spectroscopy (FTIR), were carried out after the silver nanoparticles have been collected prior coating. As a consequence, the effectiveness is determined based on the conductivity test, and the resulting Ag NPs are then applied to the c-si layer of the solar panel. Additionally, a modelling and experimental analysis are performed in this study to ascertain the suggested framework's ability to measure energy before and after coating panels with Ag NPs. Specifically, the Voltage Current (VI) and Power Voltage (PV) characteristics were validated in this study for analyzing the effectiveness and the obtained results revealed that the coating of green synthesized Ag NPs generated 2 % more power than the reference solar panel under the same conditions. Further, hardware testing and simulation were both used to confirm the outcomes and effectiveness of the suggested method. The open circuit voltage (Voc), short circuit current (Isc), maximum peak voltage (Vmp), maximum peak current (Imp), and efficiency are taken into account when assessing how well the suggested system performs at tracking. Moreover, the current density characteristics were evaluated with respect to various irradiation conditions for both the typical solar as well as Ag NPs coated panels. From the observation, it is noted that the efficiency level of coated panel was improved up to 19.20 %, 18 %, and 17.20 % for the irradiations of 200 W/m2, 500 W/m2, and 1000 W/m2 respectively.

Effect of 3.5 % NaCl solution with different Na2S concentrations on ultrasonic cavitation erosion behaviors of HVOF sprayed WC-Ni coatings

In this article, the WC-10Ni coatings were fabricated by HVOF spray, then the ultrasonic cavitation erosion performances of the coatings in distilled water and 3.5 wt% NaCl solution with various Na2S concentrations (0, 20 and 200 ppm) were investigated. The results of the cumulative volume loss of the coating in different mediums showed that the coating exhibited enhanced cavitation erosion resistance with the increase of Na2S concentrations in medium. The reason for the improvement on the cavitation erosion performance was the growth of corrosion product films containing sulphide. In comparison with the coating after cavitation erosion in medium without Na2S, no large craters and deep grooves were observed on the eroded coating surface in medium with Na2S. The ultrasonic cavitation damage of the coating manifests as the spall of the metal binder phase (Ni) and exposure of the hard phase (WC).