Nanoparticle Coatings Research Articles

Green synthesized silver nanoparticles from eucalyptus leaves can enhance shelf life of banana without penetrating in pulp.

Bananas are exposed to serious post-harvest problems resulting in agricultural and economic losses across the world. The severity of problem is linked with the process of rapid ripening and pathogens attack. Such problems have led to economic losses as well as a lower yield of nutritionally rich bananas. The global demand to increase the life span of bananas and their protection from pathogens-borne diseases urged the use of antimicrobial edible coatings of nanoparticles. The present experiment has explored the innovative development of green synthesized nanoparticles from Eucalyptus leaf extract (ELE) to increase the shelf life of bananas up to 32 days from the day of collection. Statistically significant results were recorded (P = 0.05) by applying five different concentrations of silver nanoparticles (AgNPs) in ranges of 0.01-0.05%. Various morphological and physiological parameters such as color, decay, firmness, weight loss, pulp to peel ratio, pH, titrable acidity (TA), phenolic contents, protein estimation, ethylene production, starch content and total soluble sugars were measured in Cavendish banana (Basrai). Bananas treated with 0.01% AgNPs showed maximum control on its ripeness over morphological and physiological changes. The increase in shelf life was in order 0.01%>0.02%>0.03%>0.04%>0.05%> control. Further, AgNPs reduced the process of ripening by controlling ethylene production. The result has also proved the safety of banana consumption by simple removal of banana peel as penetration of AgNPs from the peel to the pulp was not detected. It is recommended to use 0.01% AgNPs to enhance the shelf life of banana without effecting its nutritive value.

Impact of Longkong Pericarp Extract on the Physicochemical Properties of Alginate-Based Edible Nanoparticle Coatings and Quality Maintenance of Shrimp (Penaeus monodon) during Refrigerated Storage.

The objective of this study was to evaluate the impact of varying concentrations of longkong pericarp extract (LPE) on the physicochemical properties of alginate-based edible nanoparticle coatings (NP-ALG) on shrimp. For developing the nanoparticles, the alginate coating emulsion with different LPE concentrations (0.5, 1.0, and 1.5%) was ultrasonicated at 210 W with a frequency of 20 kHz for 10 min and a pulse duration of 1s on and 4 off. After that, the coating emulsion was separated into four treatments (T): T1: Coating solution containing basic ALG composition and without the addition of LPE or ultrasonication treatment; T2: ALG coating solution converted into nano-sized particles with ultrasonication and containing 0.5% LPE; T3: ALG coating solution converted into nano-sized particles with ultrasonication and containing 1.0% LPE; T4: ALG coating solution converted into nano-sized particles with ultrasonication and containing 1.5% LPE. A control (C) was also used, where distilled water was used instead of ALG coating. Before coating the shrimp, all the coating materials were tested for pH, viscosity, turbidity, whiteness index, particle size, and polydispersity index. The control samples had the highest pH and whiteness index and was followed by the lowest viscosity and turbidity (p < 0.05). Among the T1-T4 coating materials, T4 coating had higher turbidity, particle size, polydispersity index, but lower pH, viscosity, and whiteness index (p < 0.05). To study the quality and shelf-life of the shrimp, all coated shrimp samples were refrigerated at 4 °C for a period of 14 days. At 2-day intervals, physiochemical and microbial analyses were performed. The coated shrimp also had a lower increase in pH and weight loss over the storage period (p < 0.05). Coatings containing 1.5% LPE significantly reduced the polyphenol oxidase activity in the shrimp (p > 0.05). The addition of LPE to NP-ALG coatings demonstrated dose-dependent antioxidant activity against protein and lipid oxidation. The highest LPE concentration (1.5%) led to increased total and reactive sulfhydryl content, along with a significant decrease in carbonyl content, peroxide value, thiobarbituric acid reactive substances, p-anisidine, and totox values at the end of the storage period (p < 0.05). Additionally, NP-ALG-LPE coated shrimp samples exhibited an excellent antimicrobial property and significantly inhibited the growth of total viable count, lactic acid bacteria, Enterobacteriaceae, and psychotropic bacteria during storage. These results suggested that NP-ALG-LPE 1.5% coatings effectively maintained the quality as well as extended the shelf-life of shrimp during 14 days of refrigerated storage. Therefore, the use of nanoparticle-based LPE edible coating could be a new and effective way to maintain the quality of shrimp during prolonged storage.

Intensification of Heat Transfer During Boiling and Condensation by Means of Micro- and Nanoparticle Coatings

Intensification of Heat Transfer During Boiling and Condensation by Means of Micro- and Nanoparticle Coatings

Exploring multielement nanogranular coatings to forestall implant-related infections.

As we approach the post-antibiotic era, the development of innovative antimicrobial strategies that carry out their activities through non-specific mechanisms could limit the onset and spread of drug resistance. In this context, the use of nanogranular coatings of multielement nanoparticles (NPs) conjugated to the surface of implantable biomaterials might represent a strategy to reduce the systemic drawbacks by locally confining the NPs effects against either prokaryotic or eukaryotic cells. In the present study, two new multielement nanogranular coatings combining Ag and Cu with either Ti or Mg were synthesized by a gas phase physical method and tested against pathogens isolated from periprosthetic joint infections to address their potential antimicrobial value and toxicity in an in vitro experimental setting. Overall, Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli displayed a significantly decreased adhesion when cultured on Ti-Ag-Cu and Mg-Ag-Cu coatings compared to uncoated controls, regardless of their antibiotic resistance traits. A dissimilar behavior was observed when Pseudomonas aeruginosa was cultured for 30 and 120 minutes upon the surface of Ti-Ag-Cu and Mg-Ag-Cu-coated discs. Biofilm formation was mainly reduced by the active effect of Mg-Ag-Cu compared to Ti-Ag-Cu and, again, coatings had a milder effect on P. aeruginosa, probably due to its exceptional capability of attachment and matrix production. These data were further confirmed by the evaluation of bacterial colonization on nanoparticle-coated discs through confocal microscopy. Finally, to exclude any cytotoxic effects on eukaryotic cells, the biocompatibility of NPs-coated discs was studied. Results demonstrated a viability of 95.8% and 89.4% of cells cultured in the presence of Ti-Ag-Cu and Mg-Ag-Cu discs, respectively, when compared to negative controls. In conclusion, the present study demonstrated the promising anti-adhesive features of both Ti-Ag-Cu and Mg-Ag-Cu coatings, as well as their action in hampering the biofilm formation, highlighting the safe use of the tested multi-element families of nanoparticles as new strategies against bacterial attachment to the surface of biomedical implants.

Using visible light to activate antiviral and antimicrobial properties of TiO2 nanoparticles in paints and coatings: focus on new developments for frequent-touch surfaces in hospitals.

Indoor visible-light photocatalytic activation of reactive oxygen species (ROS) over TiO2 nanoparticles in paint to kill bacteria and coat frequently touched surfaces in the medical and food industries.

Impact of Green Gold Nanoparticle Coating on Internalization, Trafficking, and Efficiency for Photothermal Therapy of Skin Cancer.

Skin cancer is a global health issue and mainly composed of melanoma and nonmelanoma cancers. For the first clinical proof of concept on humans, we decided to study good prognosis skin cancers, i.e., carcinoma basal cell. In UE, the first-line treatment remains surgical resection, healing most of the tumors, but presents aesthetic disadvantages with a high reoccurrence rate on exposed areas. Moreover, the therapeutic indications could extend to melanoma and metastasis, which is a different medical strategy that could combine this treatment. Indeed, patients with late-stage melanoma are in a therapeutic impasse, despite recent targeted and immunological therapies. Photothermal therapy using gold nanoparticles is the subject of many investigations due to their strong potential to treat cancers by physical, thermal destruction. We developed gold nanoparticles synthesized by green chemistry (gGNPs), using endemic plant extract from Reunion Island, which have previously showed their efficiency at a preclinical stage. Here, we demonstrate that these gGNPs are less cytotoxic than gold nanoparticles synthesized by Turkevich's method. Furthermore, our work describes the optimization of gGNP coating and stabilization, also taking into consideration the gGNP path in cells (endocytosis, intracellular trafficking, and exocytosis), their specificity toward cancerous cells, their cytotoxicity, and their in vivo efficiency. Finally, based on the metabolic switch of cancerous cells overexpressing Glut transporters in skin cancers, we demonstrated that glucose-stabilized gGNP (gGNP@G) enables a quick internalization, fourfold higher in cancerous cells in contrast to healthy cells with no side cytotoxicity, which is particularly relevant to target and treat cancer.

A Facile Method to Coat Nanoparticles with Lipid Bilayer Membrane: Hybrid Silica Nanoparticles Disguised as Biomembrane Vesicles by Particle Penetration of Concentrated Lipid Layers.

Natural membrane vesicles, including extracellular vesicles and enveloped viruses, participate in various events in vivo. To study and manipulate these events, biomembrane-coated nanoparticles inspired by natural membrane vesicles are developed. Herein, an efficient method is presented to prepare organic-inorganic hybrid materials in high yields that can accommodate various lipid compositions and particle sizes. To demonstrate this method, silica nanoparticles are passed through concentrated lipid layers prepared using density gradient centrifugation, followed by purification, to obtain lipid membrane-coated nanoparticles. Various lipids, including neutral, anionic, and cationic lipids, are used to prepare concentrated lipid layers. Single-particle analysis by imaging flow cytometry determines that silica nanoparticles are uniformly coated with a single lipid bilayer. Moreover, cellular uptake of silica nanoparticles is enhanced when covered with a lipid membrane containing cationic lipids. Finally, cell-free protein expression is applied to embed a membrane protein, namely the Spike protein of severe acute respiratory syndrome coronavirus 2, into the coating of the nanoparticles, with the correct orientation. Therefore, this method can be used to develop organic-inorganic hybrid nanomaterials with an inorganic core and a virus-like coating, serving as carriers for targeted delivery of cargos such as proteins, DNA, and drugs.

Corrosion Protection Evaluation of Copper Coated with a Block Copolymer and Block Coploymer/Carbon Black Nanoparticles in 3 wt% NaCl Solution

AbstractThis paper presents a successful preparation of SEBS (a copolymer polystyrene‐block‐poly (ethylene‐ran‐butylene)‐block‐polystyrene) and SEBS‐CB (SEBS‐Carbon Black nanoparticles) coatings on a copper surface following a well‐defined immersion protocol. Such coatings′ protection capacity was tested in a 3 wt% NaCl medium using potentiodynamic polarization, cyclic voltammetry (CV), and electrochemical impedance techniques (EIS). The electrochemical measurements indicate that SEBS and SEBS‐CB are cathodic‐type inhibitors mainly hindering the diffusion of oxygen molecules toward the copper substrate. It also indicates the decrease in chloride ion attack on the coated copper layer. Not only that, but it also affirms the decrease in ‘s transport to the bulk solution, resulting in our sample being further protected at more positive potential. Cu‐SEBS‐CB electrodes showed a slight improvement in corrosion protection compared to Cu‐SEBS electrodes. π‐π stacking was associated with improving the performance of these coatings. The keys functions of incorporating CB are improving the electrode conductivity and having a denser and more compact coating than that without CB. The order of inhibition efficiency obtained by potentiodynamic polarization is in good agreement with the results achieved by electrochemical impedance spectroscopy. Also, the inhibition efficiency of Cu‐SEBS and Cu‐SEBS‐CB increases with increasing the ratio of SEBS. Adsorption of SEBS and SEBS‐CB on copper surface follows the Langmuir isotherm.

Probing the interactions of guanine on silver nanoparticles by surface-enhanced Raman spectroscopy on an electrochemical system

As a typical deoxyribonucleic acid (DNA) base with diverse amino/imino groups, guanine has remarkable Raman activity; however, its Raman modes are largely forbidden in solid Raman measurements, which hinders full understanding of the chemistry of such DNA bases. Here a study on surface-enhanced Raman scattering (SERS) of guanine is reported by employing colloidal silver nanoparticles modified on the silver electrode as substrate. High-quality SERS spectra with potential dependence were obtained, shedding light on the varying adsorption behavior of guanine on the nano-surface. High-quality SERS spectra have also been obtained for picolinic acid molecules. The good stability and homogeneous size distribution of silver nanoparticle coatings provide a highly SERS-active substrate for detecting DNA-bases and probing their local interactions.

Zaštita od korozije mekog čelika korišćenjem premaza od nanomaterijala

Effectiveness of nanoparticle coatings in preventing corrosion of mild steel metal samples were experimentally determined. TiO2 and ZrO2 nanoparticles coatings were done by brush coating. Different samples were prepared by varying the parameters such as thickness of coatings, concentration of nanoparticles and temperature of heat treatment. Corrosion rate of both uncoated mild steel and coated using TiO2, ZrO2 samples was determined in the corrosive environments of 1M HCl and 3.5 wt% NaCl. From the experiments it was found that the coated mild steel samples prepared at temperature 80oC are more effective than samples prepared at 200 oC. It is observed that TiO2 coatings prepared with ratio 2:0.3, 0.182 mm coating thickness and heat treated at 80oC, and ZrO2 coatings with thickness of 0.185 mm, prepared from nanoparticle paste of 1:0.3 ratios, heat treated at 80 oC, have shown better protection for mild steel in 1M HCl and 3.5% NaCl solutions compared with other TiO2 and ZrO2 coatings.

A novel method for the synthesis of core-shell nanoparticles for functional applications based on long-term confinement in a radio frequency plasma.

A novel combined setup of a Haberland type gas aggregation source and a secondary radio frequency discharge is used to generate, confine, and coat nanoparticles over much longer time scales than traditional in-flight treatment. The process is precisely monitored using localized surface plasmon resonance and Fourier-transform infrared spectroscopy as in situ diagnostics. They indicate that both untreated and treated particles can be confined for extended time periods (at least one hour) with minimal losses. During the entire confinement time, the particle sizes do not show considerable alterations, enabling multiple well-defined modifications of the seed nanoparticles in this synthesis approach. The approach is demonstrated by generating Ag@SiO2 nanoparticles with a well-defined surface coating. The in situ diagnostics provide insights into the growth kinetics of the applied coating and are linked to the coating properties by using ex situ transmission electron microscopy and energy dispersive X-ray spectroscopy. Surface coating is shown to occur in two phases: first, singular seeds appear on the particle surface which then grow to cover the entire particle surface over 3 to 5 minutes. Afterwards, deposition occurs via surface growth which coincides with lower deposition rates. Our setup offers full control for various treatment options, which is demonstrated by coating the nanoparticles with a SiO2 layer followed by the etching of the part of the applied coating using hydrogen. Thus, complex multi-step nanofabrication, e.g., using different monomers, as well as very large coating thicknesses is possible.

Effective heterogeneous Fenton-like degradation of antibiotics by ferroferric oxide nanoparticle coated reduced iron powder with accelerated Fe(ii)/Fe(iii) redox cycling

In this study, we present a novel strategy of accelerating cycle of Fe(ii)/Fe(iii) in iron-mediated catalyst for heterogeneous Fenton-like processes.

Nanostructured Semi-Transparent TiO2 Nanoparticle Coatings Produced by Magnetron-Based Gas Aggregation Source

A novel strategy to produce semi-transparent TiO2 nanoparticle-based coatings is investigated. This two-step strategy utilizes a magnetron-based gas aggregation source of Ti nanoparticles that are subsequently annealed in air at the temperature of 450 °C. It is shown that by using this technique, it is possible to fabricate highly porous and patterned TiO2 nanoparticle coatings with an optical band gap of around 3.0 eV on the substrate materials commonly used as transparent electrodes in photovoltaic applications or for water-splitting. In addition, it is shown that the morphology of the resulting coatings may be varied by changing the angle between the direction of the substrate and the incoming beam of nanoparticles. As demonstrated, the tilting of the substrate leads to the formation of columnar nanoparticle films.

Artificial and Naturally Derived Phospholipidic Bilayers as Smart Coatings of Solid-State Nanoparticles: Current Works and Perspectives in Cancer Therapy

Recent advances in nanomedicine toward cancer treatment have considered exploiting liposomes and extracellular vesicles as effective cargos to deliver therapeutic agents to tumor cells. Meanwhile, solid-state nanoparticles are continuing to attract interest for their great medical potential thanks to their countless properties and possible applications. However, possible drawbacks arising from the use of nanoparticles in nanomedicine, such as the nonspecific uptake of these materials in healthy organs, their aggregation in biological environments and their possible immunogenicity, must be taken into account. Considering these limitations and the intrinsic capability of phospholipidic bilayers to act as a biocompatible shield, their exploitation for effectively encasing solid-state nanoparticles seems a promising strategy to broaden the frontiers of cancer nanomedicine, also providing the possibility to engineer the lipid bilayers to further enhance the therapeutic potential of such nanotools. This work aims to give a comprehensive overview of the latest developments in the use of artificial liposomes and naturally derived extracellular vesicles for the coating of solid-state nanoparticles for cancer treatment, starting from in vitro works until the up-to-date advances and current limitations of these nanopharmaceutics in clinical applications, passing through in vivo and 3D cultures studies.

Characteristics of the Protein Coating and Functional Properties of Cadmium Sulfide Nanoparticles Obtained by Microbial Synthesis

Characteristics of the Protein Coating and Functional Properties of Cadmium Sulfide Nanoparticles Obtained by Microbial Synthesis

Applying behavioral studies to the ecotoxicology of corals: A case study on Acropora millepora

Behavioral responses are considered sensitive and effective indicators of organism stress. As the demand for standardized coral toxicity tests grows, innovative tools that allow for automatic and quantitative measurements of these behaviors may complement ecotoxicological studies. The rapid growth of competitive marine algae in aquaculture systems is a major issue for generating coral spat for reef restoration, and the application of non-toxic antifouling (AF) coatings might effectively mitigate this issue. While these coatings do not appear to be toxic to sensitive coral larvae, their potential to affect larval mobility has not been tested. In this context, we tested the effect of three recently-developed and potentially non-toxic AF coatings: (i) antiadhesive, (ii) cerium dioxide (CeO2-x) nanoparticle, and (iii) encapsulated biocide dichlorooctylisothiazolinone (DCOIT) on the swimming velocity and activity of Acropora millepora coral larvae for potential use in reef-restoration activities. The behavior of 32 coral larvae per AF treatment were recorded, each for 25 min, in a self-constructed dark box with two camera recording sets in parallel. The tracking analysis was performed with the software Noldus EthoVision XT. The mean larval swimming velocity on control tiles of 93.1 ± 5.6 mm min-1 (and activity of 62.8 ± 5.2%) was nearly 2-fold faster (higher) than on the antiadhesive, (CeO2-x) nanoparticle and DCOIT coatings, respectively. Larvae exposed to the DCOIT-coated tiles remained almost stationary. Although the underlying cause and consequence of these results require further investigation, tracking of coral larval swimming behavior was identified as a reliable and feasible method for assessing potential non-lethal responses to AF coatings. As changes in behavior could have significant consequences for larval survival and settlement, they are important endpoints to consider, and the quantification of behavioral responses may be a meaningful and sensitive tool. Therefore, we recommend the use of behavioral studies for coral larval assessments in ecotoxicology as a valuable endpoint. For methodological standardization and implementation, our study also features a detailed guide for video-processing and track analysis of A. millepora coral larvae in EthoVision.

Feasibility of Carbon Nanoparticle Coatings as Protective Barriers for Copper─Wetting Assessment.

Copper is extensively used in a wide range of industrial and daily-life applications, varying from heat exchangers to electrical wiring. Although it is protected from oxidation by its native oxide layer, when subjected to harsh environmental conditions─such as in coastal regions─this metal can rapidly degrade. Therefore, in this study, we analyze the potential use of carbon nanoparticle coatings as protective barriers due to their intrinsic hydrophobic wetting behavior. The nanocarbon coatings were produced via electrophoretic deposition on Cu platelets and characterized via scanning electron microscopy, confocal laser scanning microscopy, and sessile drop test; the latter being the primary focus since it provides insights into the wetting behavior of the produced coatings. Among the measured coatings, graphite flakes, graphene oxide, and carbon nanotube (CNT) coatings showed superhydrophobic behavior. Based on their wetting behavior, and specifically for electrical applications, CNT coatings showed the most promising results since these coatings do not significantly impact the substrate's electrical conductivity. Although CNT agglomerates do not affect the wetting behavior of the attained coatings, the coating's thickness plays an important role. Therefore, to completely coat the substrate, the CNT coating should be sufficiently thick─above approximately 1 μm.

Antibacterial Polysulfone Nanofiber Functionalized with Green Silver Nanoparticles by a Facile Wetting Method for Microbial Corrosion Protection

The introduction of antimicrobial nanoparticles into nanofiber coatings is significant for enhancing microbial corrosion protection. Here, electrospun polysulfone nanofiber (PSU-Nf) and PSU-Nf functionalized with biogenic silver nanoparticles (AgNPs) coatings (PSU-Nf-AgNPs) used for Cobalt (Co) corrosion resistance in a marine environment containing Aeromonas eucrenophila (A. eucrenophila). We utilized the barrier function of the PSU-Nf and the bacterial inhibition property of the AgNPs that are synthesized using bacteria. The thickness of nanofiber coatings was 233.11 ± 33.64 µm analyzed by optical microscope and beadless morphology of nanofibers was observed using scanning electron microscope (SEM). The corrosion behavior of Co coated with PSU-Nf and PSU-Nf-AgNPs in abiotic and in the presence of the bacterium environment was investigated via polarization techniques and electrochemical impedance spectroscopy (EIS). Corrosion analysis reveals that the charge transfer resistance (Rct) increased because of the addition of the nanostructure resulting in a reduction in corrosion rate. SEM micrographs show Co surface was severely damaged by a microbial corrosive attack with severe crevices. However, the PSU-Nf and especially PSU-Nf-AgNPs coated Co surface was still covered by nanofiber coatings as the bacteria colony was not noticed. In addition, the results of the performing bacterial disk diffusion method indicated that electrospun PSU-Nf-AgNPs have good antibacterial activity against Gram-positive, Gram-negative, and model biofilm bacterium. It was found that the uncoated Co surface had severe crevices and offered poor corrosion resistance under mineral salt medium with A. eucrenophila strain. Therefore, PSU-Nf-AgNPs coated Co exhibited better corrosion resistance in mineral salt medium containing bacteria.

Improving the Powder Properties of an Active Pharmaceutical Ingredient (Ethenzamide) with a Silica Nanoparticle Coating for Direct Compaction into Tablets

To improve the powder properties of active pharmaceutical ingredients (APIs), we coated APIs with silica nanoparticles using a dry process that allowed for direct compression into tablets. The dry coating performed with different apparatuses (a batch-type high-speed shear mixer (Mechanomill) and a continuous conical screen mill (Comil)) and properties of the resulting dry-coated APIs were compared. Ethenzamide (ETZ), which has low powder flowability, was selected as the host particle to be improved and the colloidal silicas Aerosil 200 and R972 were used as the guest particles. Both coating processes and types of silica nanoparticles improved the powder flowability (angle of repose) of ETZ under unstressed conditions. Inverse gas chromatography demonstrated that dry coating with silica nanoparticles reduced the surface free energy and improved the homogeneity of the surface energy distribution of ETZ particles. Under the stress conditions of a shear cell test, the Mechnomill-based treatment improved the powder flowability of ETZ from that of untreated ETZ; however, the Comil-based treatment did not improve the flowability. The mechanical shear force exerted by Comil was apparently insufficient for interactions between host and guest particles. However, the properties of tableted ETZ were enhanced even when the silica nanoparticles were coated using Comil.

Calcium stearate nanoparticles as building blocks for mechanically durable superhydrophobic coatings

Mechanical durability and cost-efficiency are two main concerns in moving superhydrophobic coatings toward real-life applications. However, the development of inexpensive, simple, and large-scale strategies for preparing superhydrophobic coatings that are simultaneously mechanically durable and low-cost is still challenging. Herein, we proposed a one-step dip-coating approach for in situ growing calcium stearate nanoparticles on the desired substrates simply by using commercially available calcium stearate and a suitable selection of solvents. The resulting superhydrophobic calcium stearate nanoparticle coatings show excellent mechanical durability under 100 cycles of sandpaper abrasion and 300 cycles of tape peeling, good stability towards UV light irradiation, thermal treatment and organic solvents. Furthermore, the as-prepared calcium stearate nanoparticle-coated polyester filter cloth was successfully demonstrated for oil/water separation. It is believed that such simple, rapid and cost-efficient approach provide a valid strategy and promising applications for large-scale fabrication of mechanically durable superhydrophobic coatings.