Publications

Abstract: The limited water solubility and environmental instability of natural pesticidal compounds impede their broader agricultural use. This study reports an amphiphile-assisted nanoprecipitation method to imbibe azadirachtin-rich neem seed extract (NSE) within a glycine carrier matrix, yielding a stable nanocomposite biopesticide. The formulation, prepared using polyoxyethylene sorbitan monooleate as a stabilizer and glycine as the matrix former, followed by lyophilization, exhibited a hydrodynamic diameter of ∼8 nm when redispersed in water. This glycine nanopesticide (GNP) significantly improved the photostability of azadirachtin under UV-AB irradiation (2000 μW/cm2); spectrophotometric analysis revealed a 27.7% reduction in photodegradation over a 4 day period compared to unformulated NSE powder demonstrated dialysis-based in vitro release assay showed sustained release, with 68.2 ± 2.1% released over 7 days, fitting an exponential model with a time constant of 37.6 h. Contact bioassays against Spodoptera frugiperda larvae revealed enhanced larvicidal potency. LC50 values showed a 1.5- to 6.6-fold improvement compared to unformulated NSE over 11 days. On day 7, GNP had an LC50 of 0.13 mg/mL, compared to 0.86 mg/mL for NSE powder. The nanoformulation also improved wettability on tomato leaves, reducing the contact angle from 99.0° ± 1.6° (DI water) to ∼60° at a concentration of 100 mg/mL GNP. This approach offers a practical method for improving the stability, delivery, and efficacy of hydrophobic biopesticides. 

Galvanized steel is often used in the food industry due to its durability, strength, and lower cost relative to stainless steel. Herein, we report a coating method for galvanized steel that exhibits superhydrophobicity and antifouling capabilities, effectively inhibiting the attachment of fungi, bacteria, and mud. This coating was fabricated through a two-step process involving the immobilization of silica nanoparticles and subsequent chemisorption of an organosilane layer with low surface energy. The resultant coating yielded a static water contact angle of 157 ± 3.6°. Over a period of seven days, this coating achieved log10 reductions of 2.6 ± 0.1 and 2.9 ± 0.1 in the attachment of the bacterial strains of Salmonella enterica and Listeria innocua, respectively. Additional testing revealed a marked reduction in adherence of Aspergillus niger fungus. Following immersion in mud, coated surfaces showed an evident reduction in mud attachment in comparison to the original steel surfaces. Specifically, when tested with mud with a viscosity of ∼90,000 cP, the mud attachment percentage for the untreated steel surfaces and the coated steel surfaces was quantified as 94.57 ± 1.64% and 6.81 ± 2.43%, respectively. The electrochemical characterization of the coated steel, conducted in the presence of Salmonella enterica, revealed a 60.4 ± 10.4% decrease in the corrosion rate compared to the bare steel. The prospect of implementing the developed coating technology on galvanized steel surfaces—including but not limited to grain storage silos as well as various food-related storage units and containers—presents an opportunity for significant progression within the multidisciplinary fields of food engineering, safety, and processing. 

Food package films serve the important functions of preserving food quality, extending shelf life, and protecting against external contaminants while also providing a barrier to moisture and oxygen. In consideration of the increasing frequency of foodborne outbreaks, there is a growing demand for food packaging films with additional functionality to prevent cross-contamination and the attachment of pathogens, thereby enhancing bacterial safety. Herein, we report a one-step fabrication approach relying on electrospinning of a blend of polyvinyl chloride (PVC) and polydimethylsiloxane (PDMS) together with nanodiamond (ND) on a rotating drum collector for the formation of bacterially antifouling food package films. In this approach, by adjusting the concentrations of PVC, PDMS, and ND and the drum angular velocity, the nanofiber diameter could be tuned in the range of 0.4 μm to 2.0 μm. Furthermore, these process parameters could also be used to modulate the water contact angle on the resultant films, with a minimum contact angle of 136.2 ± 5.6° and a maximum of 159.5 ± 3.8°. The lowest water contact angles were observed for films with bare PVC fibers while the highest contact angles were seen for films with nanocomposite fibers containing ND and PVC/PDMS. Compared with the films with bare PVC, nanocomposite films with ND-PVC/PDMS achieved up to 99.8 % and 99.6 % reduction in bacterial adhesion against S. typhimurium LT2 and Listeria innocua, respectively. The tensile strength of nanofibrous PVC film can be increased from 1.2 ± 0.4 MPa to 4.4 ± 0.3 MPa by the inclusion of PDMS (11 wt.%) and further increased to 8.9 ± 0.3 MPa with the additional inclusion of ND (PVC/PDMS/ND 110.1 wt.%). Considering the notable antifouling properties against bacteria and the improved mechanical characteristics, these nanocomposite films represent a noteworthy step in the development of sustainable and active food packaging solutions for a safer and healthier food supply chain. 

Recently, there has been growing interest in the hierarchical assemblies of zwitterionic betaine amphiphiles across various fields due to their utility as stimuli-responsive materials. Herein, we systematically investigate the binary supramolecular assembly of zwitterionic amido betaines and diamines to determine how alkyl chain length of amido betaines (CnDAB) and amine degree of diamines influence their relaxation dynamics of the resultant coacervates. To this end, we synthesized five CnDAB molecules with systematically varying carbon chain lengths (n = 12, 14, 16, 18, and 20) and conjugated them with three different diamines (ethylenediamine, EDA; n,n'-dimethylethylenediamine, DMEDA; and n,n,n',n'-tetramethylethylenediamine,TMEDA). We employed rheology to compare the bulk properties and relaxation dynamics of these assemblies as well as to gain insight into their responsiveness to pH stimulus. All betaine/diamine co-assemblies for all pH values showed shear-thinning behavior while the onset of shear thinning behavior showed some variation for the shear rate inducing such an onset. By changing molecular architecture of co-assembling pairs, zero-shear viscosity values varied from ∼10−1 Pa s to ∼103 Pa s at a concentration of 100 mM CnDAB and 50 mM diamine in water. Four-order-of-magnitude difference in viscosity with small changes in molecular architecture and pH indicates that precise tuning of the rheological properties is possible simply by controlling the self-assembly tendencies and nano-to-micro scale aggregation morphologies through bi-molecular design. Out of 15 different combinations of betaine and diamine pairs studied, the primary amine EDA conjugated with C18DAB resulted in the highest degree of pH-controlled viscosity changes (i.e., highest pH-responsivity). Below 16-carbon alkyl chains on the betaines, pH responsiveness mostly disappeared. Overall, this systematic study brings new insights into the molecular structure-property relationships of amido betaine/diamine systems, which are widely used in diverse sets of applications and fields. 

Bacterial fouling is a persistent problem causing the deterioration and failure of functional surfaces for industrial equipment/components; numerous human, animal, and plant infections/diseases; and energy waste due to the inefficiencies at internal and external geometries of transport systems. This work gains new insights into the effect of surface roughness on bacterial fouling by systematically studying bacterial adhesion on model hydrophobic (methyl-terminated) surfaces with roughness scales spanning from ∼2 nm to ∼390 nm. Additionally, a surface energy integration framework is developed to elucidate the role of surface roughness on the energetics of bacteria and substrate interactions. For a given bacteria type and surface chemistry; the extent of bacterial fouling was found to demonstrate up to a 75-fold variation with surface roughness. For the cases showing hydrophobic wetting behavior, both increased effective surface area with increasing roughness and decreased activation energy with increased surface roughness was concluded to enhance the extent of bacterial adhesion. For the cases of superhydrophobic surfaces, the combination of factors including (i) the surpassing of Laplace pressure force of interstitial air over bacterial adhesive force, (ii) the reduced effective substrate area for bacteria wall due to air gaps to have direct/solid contact, and (iii) the reduction of attractive van der Waals force that holds adhering bacteria on the substrate were summarized to weaken the bacterial adhesion. Overall, this study is significant in the context of designing antifouling coatings and systems as well as explaining variations in bacterial contamination and biofilm formation processes on functional surfaces. 

Bacterial adhesion to material surfaces is a prominent cause of bacterial infections and diseases. Antifouling coatings have garnered increasing attention in recent years as a means to address this significant challenge in surface hygiene and microbiological safety. In this study, a multifunctional antibacterial coating that employs a simultaneous release-inactivation and superhydrophobic antiadhesion strategy is presented. In this context, mesoporous silica nanoparticles were synthesized and chemically modified to provide dual functionality. First, the deposition of nanoparticles establishes a nanotopography with a low surface energy, resulting in a superhydrophobic surface, which minimizes the contact between aqueous bacterial suspensions and the surfaces. Second, periodic nanopores within the nanoparticles could be infused with cinnamon essential oil, which gradually diffuses into the surrounding medium, leading to the inactivation of planktonic bacteria. Quantitatively, the developed coating exhibited notable antibacterial and antiadhesion properties, reducing the proliferation of Gram-negative E. coli and Gram-positive S. aureus by 99.9% and 99.6%, respectively. It also demonstrated excellent mechanical and chemical durability. With its facile, low-cost, and universal fabrication, as well as its metal-free and fluorine-free properties, we anticipate this coating to have significant potential in mitigating the risk of bacterial contamination in biomedical applications and the food industry. 

Recently, the interest in stimuli-responsive and adaptable materials has continuously grown in various fields and applications. For such responsive systems, different triggers, including pH, light, pressure, temperature, and electric field, have been utilized to control dynamics and assembly. Among these, pH is one of the most convenient, energy-efficient, and economic modalities. Besides, plenty of traditional materials have poor thermal and salt stability, limiting their applications. Herein, we report a new design of a pH-responsive viscoelastic supramolecular complex (VSC) based on commplexation of a new long-chain amino-amide and maleic acid. The system demonstrated a sol–gel-sol transition from pH 2 to 10, with the largest static viscosity occurring at pH 6 (∼1000 Pa·s) and the smallest viscosity at pH 4 (∼3.3 Pa·s), indicating ∼ 300-fold control over the viscosity. For a given concentration, the static viscosity of VSC was about 15 times larger than that of CTAB/NaSal, a well-established dynamic viscoelastic system, and no pH-responsiveness was observed for the traditional system. In addition, the VSC demonstrated a superior temperature tolerance and lower temperature dependence. The potential of these intriguing dynamics viscoelastic systems was evaluated for hydraulic fracturing and enhanced oil recovery applications. Proppant settling velocity of DMAA/MA was 500 ∼ 1000 times lower than that of CTAB/NaSal and common traditional polymers. Likewise, the oil recovery percentage could be significantly improved with the utilization of DMAA/MA compared to the CTAB/NaSal (86 % vs 52 %). Aside from applications in hydraulic fracturing and enhanced oil recovery, we anticipate that the intriguing rheological properties of this viscoelastic system can be beneficial for other chemical engineering applications including personal care products, cosmetics, lubricants, and biomedical gels. 

Stimuli-responsive materials are increasingly needed for the development of smart electronic, mechanical, and biological devices and systems relying on switchable, tunable, and adaptable properties. Herein, we report a novel pH- and temperature-responsive binary supramolecular assembly involving a long-chain hydroxyamino amide (HAA) and an inorganic hydrotrope, boric acid, with highly tunable viscous and viscoelastic properties. The system under investigation demonstrates a high degree of control over its viscosity, with the capacity to achieve over four orders of magnitude of control through the concomitant manipulation of pH and temperature. In addition, the transformation from non-Maxwellian to Maxwellian fluid behavior could also be induced by changing the pH and temperature. Switchable rheological properties were ascribed to the morphological transformation between spherical vesicles, aggregated/fused spherical vesicles, and bicontinuous gyroid structures revealed by cryo-TEM studies. The observed transitions are attributed to the modulation of the head group spacing between HAA molecules under different pH conditions. Specifically, acidic conditions induce electrostatic repulsion between the protonated amino head groups, leading to an increased spacing. Conversely, under basic conditions, the HAA head group spacing is reduced due to the intercalation of tetrahydroxyborate, facilitated by hydrogen bonding. 

Increasing concerns revolve around bacterial cross-contamination of leafy green vegetables via food-contact surfaces. Given that stainless-steel is among the commonly used food-contact surfaces, this study reports a coating strategy enhancing its hygiene and microbiological safety through an antifouling approach via superhydrophobicity. The developed method involves growing a nickel-nanodiamond nanocomposite film on 304 stainless-steel via electroplating and sequential functionalization of the outer surface layer with nonpolar organosilane molecules via polydopamine moieties. The resultant superhydrophobic stainless-steel surfaces had a static water contact angle of 156.3 ± 1.9° with only 2.3 ± 0.5° contact angle hysteresis. Application of the coating to stainless-steel was demonstrated to yield 2.3 ± 0.6 log10 and 2.0 ± 0.9 log10 reductions in the number of adherent gram-negative Escherichia coli O157:H7 and gram-positive Listeria innocua cells, respectively. These population reductions were shown to be statistically significant (α = 0.05). Coated stainless-steel also resisted fouling when contacted with contaminated romaine lettuce leaves and maintained significant non-wetting character when abraded with sand or contacted with high concentration surfactant solutions. The incorporation of superhydrophobic stainless-steel surfaces into food processing equipment used for washing and packaging leafy green vegetables has the potential to mitigate the transmission of pathogenic bacteria within food production facilities. 

The demand for hip arthroplasties and other joint replacement orthopedic surgeries is on the rise. Combined with the emergence of antibiotic drug resistant strains of pathogenic bacteria, there is an increasing need for the development of bacterial antifouling surface treatment technologies which can be applied to titanium alloy medical devices. Herein is reported the development of a durable, fluorine-free superhydrophobic surface treatment for Ti6Al4V, fabricated through facile means without the use of HF or fluoropolymers, utilizing safe reagents under mild reaction conditions. Nanoscale texturing was created with an alkaline hydrothermal process. An alkyl surface chemistry was imparted via the deposition of an alkyl self-assembled monolayer to achieve superhydrophobic, non-wetting behavior. This superhydrophobic surface is capable of imposing 1.55 ± 0.13 and 1.72 ± 0.23 log10 reductions in the adherent populations of Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Pseudomonas aeruginosa (P. aeruginosa) bacteria, respectively. This represents a safe route to a significant potential mitigation in the costs and dangers arising from medical device associated infections. 

Biopesticides have become a global trend in order to minimize the hazards derived from synthetic chemical pesticides and improve the safety, efficacy, and environmental friendliness of agricultural pest management. Herein, we report a novel biopesticide composite encapsulating azadirachtin with the size of 260.9 ± 6.8 nm and its effects on the insect pest Spodoptera frugiperda (fall armyworm). The nanocomposite biopesticide was produced via nano emulsification and freeze-drying process using whey protein isolate as a nanocarrier matrix to encapsulate azadirachtin, a natural insect-killing compound obtained from neem seed. We found that the nanocomposite biopesticide acted quicker and with greater efficacy than bulk azadirachtin treatment with corresponding LC50 values within 11 days of S. frugiperda larvae survival. Through confocal microscopy, we found the enhanced biodistribution of the nanocomposite to all parts of the insect body. Photodegradation assays revealed an enhanced UV stability facilitated by light-scattering stemming from the intrinsic nanostructure and UV scavenging vitamin-E component. 

Protecting fresh-packed produce microbiological safety against pre- and post-harvest microbial pathogen contamination requires innovative antimicrobial strategies. Although largely ignored in the scientific literature, there exists the potential for gross failure in food safety protection of fresh fruits and vegetables leading to opportunity for multiple produce contamination events to occur during production and post-harvest handling of food crops. The primary objective of this research was to determine the efficacy of plant-derived antimicrobial-loaded nanoparticles to reduce Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium on spinach leaf surfaces whilst simulating multiple pathogen contamination events (pre-harvest and post-harvest). Spinach samples were inoculated with a blend of E. coli O157:H7 and S. Typhimurium, each diluted to ~8.0 log10 CFU/mL. The inoculated samples were then submerged in solutions containing nanoparticles loaded with geraniol (GPN; 0.5 wt.% geraniol), unencapsulated geraniol (UG; 0.5 wt.%), or 200 ppm chlorine (HOCl; pH 7.0), with untreated samples serving for controls. Following antimicrobial treatment application, samples were collected for surviving pathogen enumeration or were placed under refrigeration (5°C) for up to 10 days, with periodic enumeration of pathogen loads. After 3 days of refrigerated storage, all samples were removed, aseptically opened and subjected to a second inoculation with both pathogens. Treatment of spinach surfaces with encapsulated geraniol reduced both pathogens to non-detectable numbers within 7 days of refrigerated storage, even with a second contamination event occurring 3 days after experiment initiation. Similar results were observed with the UG treatment, except that upon recontamination at day 3, a higher pathogen load was detected on UG-treated spinach vs. GPN-treated spinach. These data fill a research gap by providing a novel tool to reduce enteric bacterial pathogens on spinach surfaces despite multiple contamination events, a potential food safety risk for minimally processed edible produce 

Foodborne illness outbreaks caused by bacterial pathogens may take place on a large scale and result in millions of hospitalizations and thousands of deaths every year throughout the world. One key strategy for dealing with this global issue is the design of smart surfaces and coatings which inhibit and reduce bacterial attachment. This can mitigate contamination and cross-contamination during farm-to-table food processing, promoting food safety, and hygiene. Herein, we reported a durable superhydrophobic coating on aluminum surfaces fabricated by sequential deposition of ultrahard nanodiamond, self-assembly of l-3,4-dihydroxyphenylalanine (l-dopamine), and chemical modification with an organoflurosilane. This coating achieved static, advancing, and receding water contact angles of 159.0 ± 2.5°,154.0 ± 2.4°; and 153.7 ± 1.7°, respectively, representing water super-repellency with a low overall root mean square (rms) roughness of 173.5 ± 69.6 nm. In comparison to the bare, unmodified aluminum, the coated aluminum surfaces prevented the attachment of 99.5% of applied Escherichia coli O157:H7 (E.coli O157:H7) and 99.0% of Staphylococcus aureus (S. aureus) cells. In addition, due to the presence of nanodiamond building blocks, the coated surfaces demonstrated a high mechanical resistance against scratching and endured at least 10,000 shearing/rubbing cycles with a nylon surface. Overall, we anticipate that implementation of this coating could improve safety and hygiene of food-contact surfaces that require harsher mechanical operational conditions. 

Viscosity modifying agents are one of the most critical components of hydraulic fracturing fluids, ensuring the efficient transport and deposition of proppant into fissures. To improve the productivity index of hydraulic fracturing processes, better viscosifiers with a higher proppant carrying capacity and a lower potential of formation damage are needed. In this work, we report the development of a novel viscoelastic system relying on the complexation of zwitterionic octadecylamidopropyl betaine (OAPB) and diethylenetriamine (DTA) in water. At a concentration of 2 wt%, the zwitterionic complex fluid had a static viscosity of 9 to 200 poise, which could be reversibly adjusted by changing the suspension pH. The degree of pH-responsiveness ranged from 10 to 27 depending on the shear rate. At a given concentration and optimum pH value, the zwitterionic viscosifiers showed a two-orders-of-magnitude reduction in settling velocity of proppant compared to polyacrylamide solution (slickwater). By adjusting the pH between 4 and 8, the networked structure of the gel could be fully assembled and disassembled. The lack of macromolecular residues at the dissembled state can be beneficial for hydraulic fracturing application in avoiding the permeation damage issues encountered in polymer and linear-gel-based fracturing fluids. The reusability and the unnecessary permanent breakers are other important characteristics of these zwitterionic viscosifiers.

Herein, we describe interfacially-assembled [7]helicene films that were deposited on graphene monolayer using the Langmuir-Schaefer deposition by utilizing the interactions of nonplanar (helicene) and planar (graphene) π–π interactions as functional antifouling coatings. Bacterial adhesion of Staphylococcus aureus on helicene—graphene films was noticeably lower than that on bare graphene, up to 96.8% reductions in bacterial adhesion. The promising bacterial antifouling characteristics of helicene films was attributed to the unique molecular geometry of helicene, i.e., nano-helix, which can hinder the nanoscale bacterial docking processes on a surface. We envision that helicene—graphene films may eventually be used as protective coatings against bacterial antifouling on the electronic components of clinical and biomedical devices.

Illness as the result of ingesting bacterially contaminated foodstuffs represents a significant annual loss of human quality of life and economic impact globally. Significant research investment has recently been made in developing new materials that can be used to construct food contacting tools and surfaces that might minimize the risk of cross-contamination of bacteria from one food item to another. This is done to mitigate the spread of bacterial contamination and resultant foodborne illness. Internet-based literature search tools such as Web of Science, Google Scholar, and Scopus were utilized to investigate publishing trends within the last 10 years related to the development of antimicrobial and antifouling surfaces with potential use in food processing applications. Technologies investigated were categorized into four major groups: antimicrobial agent–releasing coatings, contact-based antimicrobial coatings, superhydrophobic antifouling coatings, and repulsion-based antifouling coatings. The advantages for each group and technical challenges remaining before wide-scale implementation were compared. A diverse array of emerging antimicrobial and antifouling technologies were identified, designed to suit a wide range of food contact applications. Although each poses distinct and promising advantages, significant further research investment will likely be required to reliably produce effective materials economically and safely enough to equip large-scale operations such as farms, food processing facilities, and kitchens. 

Hydraulic fracturing of unconventional reservoirs has seen a boom in the last century, as a means to fulfill the growing energy demand in the world. The fracturing fluid used in the process plays a substantial role in determining the results. Hence, several research and development efforts have been geared towards developing more sustainable, efficient, and improved fracturing fluids. Herein, we present a dynamic binary complex (DBC) solution, with potential to be useful in the hydraulic fracturing domain. It has a supramolecular structure formed by the self-assembly of low molecular weight viscosifiers (LMWVs) oleic acid and diethylenetriamine into an elongated entangled network under alkaline conditions. With less than 2 wt% constituents dispersed in aqueous solution, a viscous gel that exhibits high viscosities even under shear was formed. Key features include responsiveness to pH and salinity, and a zero-shear viscosity that could be tuned by a factor of ~280 by changing the pH. Furthermore, its viscous properties were more pronounced in the presence of salt. Sand settling tests revealed its potential to hold up sand particles for extended periods of time. In conclusion, this DBC solution system has potential to be utilized as a smart salt-responsive, pH-switchable hydraulic fracturing fluid.

Concerns arising from accidental and occasional releases of novel industrial nanomaterials to the environment and waterbodies are rapidly increasing as the production and utilization levels of nanomaterials increase every day. In particular, two-dimensional nanosheets are one of the most significant emerging classes of nanomaterials used or considered for use in numerous applications and devices. This study deals with the interactions between 2D molybdenum disulfide (MoS2) nanosheets and beneficial soil bacteria. It was found that the log-reduction in the survival of Gram-positive Bacillus cereus was 2.8 (99.83%) and 4.9 (99.9988%) upon exposure to 16.0 mg/mL bulk MoS2 (macroscale) and 2D MoS2 nanosheets (nanoscale), respectively. For the case of Gram-negative Pseudomonas aeruginosa, the log-reduction values in bacterial survival were 1.9 (98.60%) and 5.4 (99.9996%) for the same concentration of bulk MoS2 and MoS2 nanosheets, respectively. Based on these findings, it is important to consider the potential toxicity of MoS2 nanosheets on beneficial soil bacteria responsible for nitrate reduction and nitrogen fixation, soil formation, decomposition of dead and decayed natural materials, and transformation of toxic compounds into nontoxic compounds to adequately assess the environmental impact of 2D nanosheets and nanomaterials.

Lack of maintenance and poor sanitation of food-contact surfaces (FCSs) can result in foodborne microbial contamination and biofilm formation. With increasing industrial concerns over food safety and hygiene, it is important to keep FCSs bacteria-free to protect the consumers from various foodborne illnesses. In the current study, we report the fabrication of highly durable nanodiamond (ND) based coatings on high-density polyethylene (HDPE), combining the chemisorption of low surface energy ligands and rigid nanotexturing. The coated HDPE surfaces resulted in static, advancing, and receding water contact angles of 151.1 ± 0.3°, 155.0 ± 1.0°, and 151.0 ± 1.9°, respectively. This superhydrophobic coating demonstrated excellent mechanical durability, retaining its highly water-repellent nature after surface abrasion with spinach leaves and onion peels, as well as after 50 cycles of sand abrasion. In comparison to bare HDPE, the adhesion of Salmonella typhimurium LT2 and Listeria innocua bacteria onto the coated surfaces was reduced by 2.1 ± 0.43 (>99.34%) and 1.6 ± 0.55 (>97.75%) log-cycles, respectively. In addition, the coated substrates successfully reduced the cross-contamination of spinach leaves by S.typhimurium LT2 and L. innocua. Overall, this study demonstrates the proof-of-concept that durable superhydrophobic coatings involving nanodiamond on HDPE have the potential to reduce bacterial cross-contamination scenarios of FCSs in food processing environments. 

Bacterial pathogens are responsible for millions of cases of illnesses and deaths each year throughout the world. The development of novel surfaces and coatings that effectively inhibit and prevent bacterial attachment, proliferation, and growth is one of the crucial steps for tackling this global challenge. Herein, we report a dual-functional coating for aluminum surfaces that relies on the controlled immobilization of lysozyme enzyme (muramidase) into interstitial spaces of presintered, nanostructured thin film based on ∼200 nm silica nanoparticles and the sequential chemisorption of an organofluorosilane to the available interfacial areas. The mean diameter of the resultant lysozyme microdomains was 3.1 ± 2.5 μm with an average spacing of 8.01 ± 6.8 μm, leading to a surface coverage of 15.32%. The coating had an overall root-mean-square (rms) roughness of 539 ± 137 nm and roughness factor of 1.50 ± 0.1, and demonstrated static, advancing, and receding water contact angles of 159.0 ± 1.0°, 155.4 ± 0.6°, and 154.4 ± 0.6°, respectively. Compared to the planar aluminum, the coated surfaces produced a 6.5 ± 0.1 (>99.99997%) and 4.0 ± 0.1 (>99.99%) log-cycle reductions in bacterial surfaces colonization against Gram-negative Salmonella Typhimurium LT2 and Gram-positive Listeria innocua, respectively. We anticipate that the implementation of such a coating strategy on healthcare environments and surfaces and food-contact surfaces can significantly reduce or eliminate potential risks associated with various contamination and cross-contamination scenarios.

Solar distillation system depends on adhesion of water molecules inside the glass cover of solar stills. Regular glass surfaces are prone to adsorbing other unwanted compounds and in turn lower the percentage of recovery of pure distilled water. In this study, the production of purified distilled water was compared with and without the use of graphene-based surface modifiers. In areas where salt content is high, the first pass is still usually laden with salts. Hence, to improve adhesion of water and rejection of salts, both the inside glass cover surfaces and the metal absorber plates were modified using oxygen plasma treatment and graphene surface enhancement. Results showed a 48.9% improvement of distilled water recovery from an initial recovery of 2.90 L/m2 per day to an average of 4.32 L/m2 per day. In addition, the resulting distilled water passes the World Health Organization drinking water standards such as pH, electrical conductivity (EC), and salinity. The average reduction in EC was 96.52%, an average increase of 5.06% of pH, and an average reduction of salinity of 96.52%, all measured at the highest brine salinity of 5%. The reported value of EC was 23.33 μS/cm, a lowest and near-neutral pH of 6.85, and an average salinity of 12.10 ppm. 

As a result of frequent outbreaks occurring due to poor hygiene and improper sanitation of processing environments, there has been an increasing demand for the development of food-contact surface materials that intrinsically inhibit and reduce likelihood of potential microbial adherence and biofilm formation. Herein, we report the synergistic utilization of surface nanotexturing and chemical modifications with nonpolar functional groups on aluminum surfaces to produce coatings having bacterial super-repellant and mud anti-fouling characteristics. Using these coatings, the attachment of Salmonella Typhimurium LT2 and Listeria innocua as pathogen surrogates was reduced more than 99.0%, compared to the bare aluminum surfaces. In addition, the coating strongly resisted the adhesion of mud, showing a 10-fold reduction in the area of mud adhesion upon submerging in mud solution. Moreover, this method is both versatile and scalable, involving inert and biocompatible building blocks. Overall, this study contributes to the field of food safety through the design and development of novel coatings for achieving improved food safety and hygiene.

Herein, we describe a novel and simple pH-switchable oil-in-water emulsion system prepared by intermolecular assembly of  an amino-amide and a trace amount of citric acid. The resultant supramolecular complex, which demonstrated highly pH-responsive properties, was characterized with various techniques, including  attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, ultraviolet–visible (UV–vis) spectroscopy, zeta potential, dynamic light scattering (DLS), surface tension, and interfacial tension. The switchable cyles between emulsification-demulsification states via adjusting the pH through the addition of acid or base were demonstrated with several types of oils. While emulsion was very stable at a pH of 2.2; a rapid phase separation was observed at and above pH of 5.5. Upon adjusting pH back to 2.2, stable emulsion could be re-assembled via dynamic intermolecular interactions. Such pH-triggered emulsification and demulsification cycles could be switched at least five times. The intriguing properties of these pH-switchable emulsions indicate their potential in several industrial applications such as enhanced oil recovery and cosmetics industry.

Herein, we report a facile approach to fabricate highly porous nanocomposites made from polycaprolactone (PCL) and boron nitride (BN) nanoplatelets using coprecipitation mixing and supercritical CO2 drying. The presence of boron nitride nanoplatelets in polycaprolactone matrix enhanced the porosity of polycaprolactone foams and also improved the interfacial compatibility with oils and nonpolar organic solvents. Through a synergistic combination of surface morphology and interfacial tension effect, PCL:BNNP foams achieved a high hydrophobicity with a contact angle of 135° while being strongly oleophilic with a near zero contact angle for oils and nonpolar organic solvents. The absorption capacity was 6.1, 5.8, 4.3, 3.7, and 3.4 for paraffin oil, silicone oil, corn oil, hexadecane, and n-hexane, respectively. Additionally, the nanocomposite foam also demonstrated promising reusability and oil stability. Overall, this study offers a novel and facile strategy for fabricating porous nanocomposite materials with a strong potential in the applications of environmental remediation.