Personal protective textiles have attracted extensive interest since Corona Virus Disease 2019 has broken out. Moreover, developing eco-friendly, multifunctional waterproof, and breathable surface is of great importance but still faces enormous challenges. Notably, good hydrophobicity and breathability are necessary for protective textiles, especially protective clothing and face masks for healthcare. Herein, the multifunctional composite coatings with good UV-resistant, anti-oxidative, hydrophobic, breathable, and photothermal performance has been rapidly created to meet protective requirements. First, the gallic acid and chitosan polymer was coated onto the cotton fabric surface. Subsequently, the modified silica sol was anchored on the coated cotton fabric surface. The successful fabrication of composite coatings was verified by RGB values obtained from the smartphone and K/S value. The present work is an advance for realizing textile hydrophobicity by utilizing fluorine-free materials, compared with the surface hydrophobicity fabricated with conventional fluorinated materials. The surface free energy has been reduced from 84.2 to27.6 mJ/m so that the modified cotton fabric could repel the ethylene glycol, hydrochloric acid, and sodium hydroxide solutions, respectively. Besides, the composite coatings possesses lower adhesion to deionized water. After 70 cycles of the sandpaper abrasion, the fluorine-free hydrophobic coatings still exhibits good hydrophobicity with WCA of 124.6 ± 0.9°, with overcoming the intrinsic drawback of the poor abrasion resistance of hydrophobic surfaces. Briefly, the present work may provide a universal strategy for rapidly creating advanced protective coatings to meet personal healthcare, and a novel method for detecting RGB values of composite coatings by smartphone.

Citrate capped gold nanoparticles (AuNPs-citrate) are the starting material for most of the academic and industrial applications using gold nanoparticles. AuNPs-citrate must usually be functionalized with organic (bio)molecules, through a ligand exchange process, to become suitable for the envisaged application. The evaluation of the efficiency of the ligand-exchange process with a simple and convenient procedure is challenging.

The consumption of famciclovir (FCV) has been increased dramatically since the outbreak of coronavirus in 2019, and the pollution and harm of FCV in waters are concerned. Here, by utilizing aryl halides on 2, 4, 6-tris(4-bromophenyl)- 1, 3, 5-triazine (BPT) and primary amine groups on benzidine (BZ), a novel conjugated microporous polymer, namely BPT-BZ-CMP, was synthesized by Buchwald-Hartwig coupling reaction and applied in the removal of FCV from aqueous solution firstly. The synthesized BPT-BZ-CMP were characterized by various methods, including FTIR, SEM, BET, and Zeta-potential. Due to the micropore structure and high specific surface area, it took only 30 min for BPT-BZ-CMP to adsorb FCV to reach an equilibrium, and the maximum adsorption capacity was 347.8 mg·g. The Liu and pseudo-second-order kinetic models properly fit the adsorption equilibrium and kinetic data, respectively. The adsorption process was a spontaneous process, and the hydrogen bonding, π-π interaction and C-H···π interaction enhanced the adsorption of FCV on BPT-BZ-CMP. BPT-BZ-CMP maintained a good adsorption capacity after four consecutive adsorption-desorption cycle experiments. This study confirmed the potential of BPT-BZ-CMP as efficient sorbent to remove FCV from aqueous solutions.

Selective bulk metal-organic frameworks (MOFs) have exhibited great potential in biomedical applications. However, topical treatments and drug elution coatings will require uniform films as drug delivery systems. This work studies the use of surface supportive MOF thin films for drug loading and releasing. More specifically, we focus on an iron-containing MOF, MIL-88B(Fe), on a COOH-terminated self-assembled monolayer (SAM) modified Au surface for encapsulating ibuprofen as a model drug. A combined experimental and computational approach was employed to study the fabrication of MIL-88B(Fe) film on functionalized Au surfaces. We used several surface characterization techniques, including infrared spectroscopy and scanning electron microscopy, to confirm the chemical composition and morphological changes of the surface after each modification step. The resulting MIL-88B(Fe) thin film was found capable of loading 8.7 wt% of ibuprofen using quartz crystal microbalance analysis. Moreover, we applied cluster simulations to study the binding mechanisms of MIL-88B(Fe) and its interactions with ibuprofen based on the density functional theory (DFT). The unsaturated Fe site was confirmed kinetically more favorable to bind to the COOH-end group on the SAM. Hydrogen bonding and π-CH interactions between ibuprofen and MIL-88B(Fe) promote ibuprofen being retained inside of the cages of MIL-88B(Fe).

Thermoplastic nanofluidic devices are promising platforms for sensing single biomolecules due to their mass fabrication capability. When the molecules are driven electrokinetically through nanofluidic networks, surface charges play a significant role in the molecular capture and transportation, especially when the thickness of the electrical double layer is close to the dimensions of the nanostructures in the device. Here, we used multivalent cations to alter the surface charge density of thermoplastic nanofluidic devices. The surface charge alteration was done by filling the device with a multivalent ionic solution, followed by withdrawal of the solution and replacing it with KCl for conductance measurement. A systematic study was performed using ionic solutions containing Mg and Al for nanochannels made of three polymers: poly(ethylene glycol) diacrylate (PEGDA), poly(methyl methacrylate) (PMMA) and cyclic olefin copolymer (COC). Overall, multivalent cations within the slip plane decreased the effective surface charge density of the device surface and the reduction rate increased with the cation valency, cation concentration and the surface charge density of thermoplastic substrates. We demonstrated that a 10-nm diameter in-plane nanopore formed in COC allowed translocation of -DNA molecules after Al modification, which is attributed to the deceased viscous drag force in the nanopore by the decreased surface charge density. This work provides a general method to manipulate surface charge density of nanofluidic devices for biomolecule resistive pulse sensing. Additionally, the experimental results support ion-ion correlations as the origin of charge inversion over specific chemical adsorption.

The adsorption process of SARS-CoV-2 Omicron spike protein to the nano-gold colloid surfaces was examined by monitoring the surface plasmon resonance (SPR) band shift of gold-nano particles ranging between diameters of d = 10-100 nm. The externally changed pH between 3 and 11 at 24.5 ± 0.4 °C initiated a reversible formation of the gold colloid aggregates, where formation/deformation of the aggregates were monitored by red/blue shift of the peak of the SPR band. There was no sign of reversible aggregation for d = 10, 15, and 20 nm gold colloids. A clear undulation of the peak shift corresponding to pH hopping between pH ~3 and ~11 was confirmed for colloidal d > 30 nm. This degree of the reversibility was compared to previously reported SARS-CoV-2 Alpha spike protein coated gold colloids. It was concluded that Omicron spike protein possesses a similar low affinity for gold nano particle d < 20 nm and possesses the higher affinity to the gold nanoparticles of d > 30 nm. However, the Omicron spike protein conformation was presumed to be more denatured compared to the SARS-CoV-2 Alpha spike protein. Our finding suggested Omicron spike protein was more acid labile/flexible.

Although the light-activated liposomes have been extensively studied for drug delivery applications, the fundamental mechanism of the drug release based on lipid compositions has not been fully understood. Especially, despite the extensive use of cholesterol in the lipid composition, the role of cholesterol in the light-activated drug release has not been studied. In this study, the influence of cholesterol on drug release from light-responsive drug-encapsulated liposomes after activated by near infrared (NIR) laser was investigated. We prepared methotrexate (MTX)-encapsulated DSPC liposomes consisting of 0 mol% (-Chol) or 35 mol% cholesterol (+Chol), with (+Au) or without gold nanorods (-Au) on the lipid bilayer to compare drug release, morphological changes, and nanostructures after laser irradiations. Transmission electron microscopy (TEM) and small angel neutron scattering (SANS) data revealed that only +Chol +Au liposomes showed partial aggregation of the liposomes after laser irradiation. Similar trends on the drug release and structural change were observed when the liposomes were heated to above chain-transition temperature. Overall, we have found that (1) inclusion of 35 mol% cholesterol enhanced the permeability of lipid bilayers above T; (2) the mechanism of laser-activated liposomal drug delivery is disrupting lipid bilayer membranes by the photothermal effect in the presence of plasmonic materials. By understanding the fundamentals of the technology, precise controlled drug release at a targeted site with great stability and repeatability is anticipated.

The significant public health concerns related to particulate matter (PM) air pollutants and the airborne transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have led to considerable interest in high-performance air filtration membranes. Highly ferroelectric polyvinylidene fluoride (PVDF) nanofiber (NF) filter membranes are successfully fabricated via electrospinning for high-performance low-cost air filtration. Spectroscopic and ferro-/piezoelectric analyses of PVDF NF show that a thinner PVDF NF typically forms a ferroelectric β phase with a confinement effect. A 70-nm PVDF NF membrane exhibits the highest fraction of β phase (87%) and the largest polarization behavior from piezoresponse force microscopy. An ultrathin 70-nm PVDF NF membrane exhibits a high PM filtration efficiency of 97.40% with a low pressure drop of 51 Pa at an air flow of 5.3 cm/s owing to the synergetic combination of the slip effect and ferroelectric dipole interaction. Additionally, the 70-nm PVDF NF membrane shows excellent thermal and chemical stabilities with negligible filtration performance degradation (air filtration efficiency of 95.99% and 87.90% and pressure drop of 55 and 65 Pa, respectively) after 24 h of heating at 120 °C and 1 h immersion in isopropanol.

Poloxamer 407 (P407) is widely used for targeted drug-delivery because it exhibits thermoresponsive gelation behavior near body temperature, stemming from a disorder-to-order transition. Hydrophobic small molecules can be encapsulated within P407; however, these additives often negatively impact the rheological properties and lower the gelation temperatures of the hydrogels, limiting their clinical utility. Here we investigate the impact of adding two BAB reverse poloxamers (RPs), 25R4 and 31R1, on the thermal transitions, rheological properties, and assembled structures of P407 both with and without incorporated small molecules. By employing a combination of differential scanning calorimetry (DSC), rheology, and small-angle x-ray scattering (SAXS), we determine distinct mechanisms for RP incorporation. While 25R4 addition promotes inter-micelle bridge formation, the highly hydrophobic 31R1 co-micellizes with P407. Small molecule addition lowers thermal transition temperatures and increases the micelle size, while RP addition mitigates the decreases in modulus traditionally associated with small molecule incorporation. This fundamental understanding yields new strategies for tuning the mechanical and structural properties of the hydrogels, enabling design of drug-loaded formulations with ideal thermal transitions for a range of clinical applications.

Hydroxychloroquine sulfate (HCQ) is a well-established antimalarial drug that has received considerable attention during the COVID-19 associated pneumonia epidemic. Gelatin is a multifunctional biomacromolecule with pharmaceutical applications and can be used to deliver HCQ. The effect of HCQ on the gelation behaviors, water mobility, and structure of gelatin was investigated to understand the interaction between the drug and its delivery carrier. The gel strength, hardness, gelling (T) and melting (T) temperatures, gelation rate (k), and water mobility of gelatin decreased with increasing amounts of HCQ. The addition of HCQ led to hydrogen bonding that interfered with triple helix formation in gelatin. Fourier transform infrared spectroscopy (FTIR) and X-ray diffractometer (XRD) analysis further confirmed that the interaction between HCQ and gelatin is primarily through hydrogen bonding. Atomic force microscopy (AFM) revealed that higher content of HCQ resulted in more and larger aggregates in gelatin. These results provide not only an important understanding of gelatin for drug delivery design but also a basis for the studying interactions between a drug and its delivery carrier.

In this work, a novel light activatable micron-sized liposomal drug carrier that has a unique capability to release drug repetitively in proportion to the cycle number of short irradiation (5 s) of near-infrared (NIR) pulsed laser is reported. We synthesized methotrexate (MTX)-loaded liposomes based on a modified reverse-phase evaporation method. Gold nanorods (AuNR) were attached to the liposomal surfaces, enabling the liposomes to release drug under short NIR irradiation via the photothermal effect. The concentrations of methotrexate (MTX) released from the liposomes were 10.6, 29.8, 43.7 and 65.9 μg/mL after one, two, three or four NIR laser cycles (1.1 W at 1064 nm, 5 s per cycle), respectively. The current finding will provide possible solution to the previously reported inconsistency in drug release from light activatable liposomal drug carriers at each activation cycle. The repeatability of drug release described in this work is believed to be due to reversible nature of the liposomes. The liposomes release drug via lipid bilayer melting when irradiated by laser due to gold nanorods' plasmonic heat on the lipid bilayer surface and quickly regain their original structure once the laser source is removed. We provided evidence of the reversible liposomal structures by monitoring the change of number densities of liposomes using a microelectrode sensor with different laser irradiation durations and powers. We also assessed the micron-sized liposome with respect to long-term stability, drug encapsulation efficiency, and drug-releasing efficiency, demonstrating the possibility of utilizing these liposomes as long-term drug delivery vehicles for various drugs.

One of the long-standing problems for the nanoparticle-based liquid-repellent coatings is their poor adhesion to substrates. For polymers of low glass transition temperature, it is highly desirable to have low temperature coating strategy to fabricate robust superhydrophobic films. Here, we report a facile method for fabricating robust, transparent, superhydrophobic films on polymer substrates. A mixture of silica particles and silica-based oligomers was spin coated on polymer substrates, followed by oxygen plasma treatment and vapor deposition of 1H,1H,2H,2H-Perfluorodecyltriethoxysilane (FDTS). The resulting superhydrophobic surface has a static contact angle at 160° and contact angle hysteresis lower than 5°. This study provides a practical solution to improve the adhesion of superhydrophobic films on polymer substrates in ambient conditions.

Gold nano-particles were coated with the spike protein (S protein) of SARS-CoV-2 and exposed to increasingly acidic conditions. Their responses were investigated by monitoring the surface plasmon resonance (SPR) band shift. As the external pH was gradually changed from neutral pH to pH ∼2 the peak of the SPR band showed a significant red-shift, with a sigmoidal feature implying the formation of the gold-protein aggregates. The coating of S protein changed the surface property of the gold enough to extract the coverage fraction of protein over nano particles, Θ, which did not exhibit clear nano-size dependence. The geometrical simulation to explain Θ showed the average axial length to be = 7. 25 nm and =8.00 nm when the S-protein was hypothesized as a prolate shape with spiking-out orientation. As the pH value externally hopped between pH∼3 and pH∼10, a behavior of reversible protein folding was observed for particles with diameters >30 nm. It was concluded that S protein adsorption conformation was impacted by the size (diameter, d) of a core nano-gold, where head-to-head dimerized S protein was estimated for d ≤ 80 nm and a in formation for d = 100 nm.

Aluminum-containing salts are commonly used as antacids and vaccine adjuvants; however, key features of functional activities remain unclear. Here, we characterized vaccine formulations based on aluminum phosphate and aluminum hydroxide and investigated the respective modes of action linking physicochemical properties and catalytic ability. TEM microscopy indicated that aluminum phosphate gel solutions are amorphous, whereas aluminum hydroxide gel solutions have a crystalline structure consistent with boehmite. At very low BSA concentrations, 100 % adsorption of the protein on aluminum hydroxide could be achieved. As the protein concentration increased, the amount of adsorbed BSA decreased as fewer vacant sites were available on the surface of the adjuvants. Notably, less than 20 % adsorption was observed in aluminum phosphate. The protein adsorption profiles should confront the requirements for vaccine immunoavailability. In terms of catalytic ability, the prepared aluminum salts were tested for their ability to drive the amphiphilic engineering of oligo(lactic acid) (OLA) onto methoxy poly(ethylene glycol). It was concluded that aluminum hydroxide, rather than aluminum phosphate, is suitable to be a vaccine adjuvant according to the morphology and antigen adsorption efficiency results; on the other hand, aluminum phosphate may be a more efficient catalyst for the synthesis of polymeric emulsifiers than aluminum hydroxide. The results provide critical mechanistic insight into aluminum-containing salts in vaccine formulations.

Lotus like materials having superhydrophobicity is attaining greater demand due to the possibility of molding them into different high end applications. The major issue related to self-cleaning superhydrophobic surfaces is their restricted mechanical properties. The development of nanotechnology has brought many advantages in the fabrication and properties of superhydrophobic surfaces and thus it enhanced the demand of superhydrophobic surfaces. Many scientific groups have studied and reported about the superhydrophobicity exhibited by graphene and its analogous derivatives. The fabrication of the devices having properties ranging from anti-sticking and self-cleaning to anti-corrosion and low friction is made possible by the incorporation of this wonderful two-dimensional material. This review focuses on the preparation and properties of graphene based superhydrophobic coating materials with special mention to the wide range of applications rendered by them.

Virus adsorption to colloidal particles is an important issue in the water quality community. Namely, if viruses can quickly and strongly associate to colloids, this can potentially lead to significant implications for the management of biohazardous wastes at water reclamation facilities. This research evaluated the adsorption of bacteriophage MS2 to colloidal suspensions of kaolinite (KAO) and fiberglass (FG). Observed pseudo first-order MS2 removal rate constants were between 0.53 and 5.1 min and between 2.4 and 3.5 min for KAO and FG, respectively. These kinetics were at least an order of magnitude faster than previously reported values when compared to data retrieved at similar colloid concentrations. Fluorescent and bright field microscopic images showed clusters of MS2 on and around the edges of the colloids, and the majority of the bound MS2 was not readily removed during a vigorous wash step, suggesting comparatively strong, operationally relevant adsorption. MS2 aggregation was observed experimentally and predicted on the basis of interaction energies calculated with XDLVO models. When virus-containing biohazardous wastes are introduced into wastewater treatment plants, removing colloids is essential.

The novel application of magnetite containing reduced graphene oxide nanosacks (MrGO-N) as electron shuttles to improve the reductive degradation of pharmaceutical pollutant, iopromide (IOP), was evaluated. The MrGO-N were synthesized by ultrasonicated nebulization process, and their physicochemical characterization was performed by potentiometric titrations, zeta potential, high resolution transmission electron microscopy (HR-TEM), X-ray diffraction, as well as by Raman and Fourier transform infrared spectroscopies. Results demonstrated the thermal reduction of precursor graphene oxide sheets, the removal of different oxygenated groups, and the successful assembly of magnetite nanoparticles (MNP) in the graphene sacks. Also, reduction experiments revealed 72 % of IOP removal efficiency and up to 2.5-fold faster degradation of this pollutant performed with MrGO-N as redox catalysts in batch assays and with sulfide as electron donor. Chemical transformation pathway of IOP provides evidence of complete dehalogenation and further transformation of aromatic ring substituents. Greater redox-mediating ability of MrGO-N was observed, which was reflected in the catalytic activity of these nanomaterials during the reductive degradation of IOP. Transformation byproducts with simpler chemical structure were identified, which could lead to complete degradation by conventional methodologies in a complementary treatment process. Redox-mediating activity of MrGO-N could potentially be applied in wastewater treatment systems in order to facilitate the biodegradation of priority contaminants.

Controllable surface morphology is requisite across a gamut of processes, industries, and applications. The surface morphology of silica-coated polystyrene microspheres was controllably modified to enable generation of both smooth and bumpy, or raspberry-like, surfaces. Although smooth and raspberry-like silica shells on polystyrene templates have been demonstrated extensively, the method described here used readily available materials to produce radical changes in surface morphology from a single polystyrene template coated in silica through a facile sol-gel reaction processes. Silica shells were deposited via a sol-gel process (using tetraethyl orthosilicate as the silica precursor) onto 1 to 2 μm diameter anionic polystyrene spheres, fabricated by emulsifier-free polymerization. By varying of the concentration of silica precursor and ammonium hydroxide catalyst and altering the electrostatic surface interactions via addition of a cationic polymeric brush, an array of surface topologies was generated. The resulting silica shells ranged from 100 to 200 nm in thickness, as measured by calcination of the polystyrene template. Empirical relations between reaction conditions and the resulting silica colloid diameter were utilized to understand the resultant silica shell topology. These results may serve as a guide to generate a versatile platform for research in the multitude of applications where polystyrene-silica core-shell particles are utilized.

In this study, multilayered films of polyethylenimine/poly (sodium-p-styrene sulfonate) (PEI)/(PSS) and type I collagen/heparin sodium (COL)/(HEP) were fabricated using the layer-by-layer technique, and fully characterized using Infrared Variable Angle Spectroscopic Ellipsometry (IRVASE) to simultaneously analyze the chemistry, thickness, and roughness of the multilayers with respect to changes in pH of the washing solution, and changes in temperature. Film topography and Young's modulus were obtained by atomic force microscopy (AFM) and nanoindentation. Our results show that with IRVASE it is possible to analyze the thickness of the multilayers prepared using a washing solution of pH 5, obtaining values of 71.7 nm and 40.3 nm for three bilayers of PEI/PSS and COL/HEP, respectively. Film roughness varies between multilayer systems, obtaining values of 37.76 nm for three bilayers of PEI/PSS and 33.58 nm for three bilayers of COL/HEP. Increasing the pH of the washing solution for PEI/PSS yielded thinner films that were less susceptible to thermal induced changes in film chemistry in the range of 25 - 150 °C. PEI/PSS films decreased in thickness with increasing temperature up to 75 °C, whereas above 75 °C film thickness increased. Through IRVASE, a transition temperature for the PEI/PSS multilayers was observed at 75 °C. Temperatures above 37 °C drastically alter the chemistry and the thickness of the COL/HEP multilayers indicating a possible degradation of the polymers. We obtained, through nanoindentation, a Young's modulus of 15000 kPa and 9000 kPa for 12 bilayers of PEI/PSS and COL/HEP, respectively. These results demonstrate that, using IRVASE, we can simultaneously evaluate the physical, chemical, and thermal properties of synthetic and natural multilayered polymeric films.

Traditionally, an interface is defined as a boundary between immiscible phases. However, previous work has shown that even when two fluids are completely miscible, they maintain a detectable "effective interface" for long times. Miscible interfaces have been studied in various systems of two fluids with a single boundary between them. However, this work has not extended to the three-phase system of a fluid droplet placed on top of a miscible pool. We show that these three-phase systems obey the same wetting conditions as immiscible systems, and that their drop shapes obey the Augmented Young-Laplace Equation. Over time, the miscible interface diffuses and the shape of the drop evolves. We place 2-microliter drops of water atop miscible poly(acrylamide) solutions. The drop is completely wetted by the subphase, and then remains detectable beneath the surface for many minutes. An initial effective interfacial tension can be approximated to be on the order of 0.5 mN/m using the capillary number. Water and poly(acrylamide) are completely miscible in all concentrations, and yet, when viewed from the side, the drop maintains a capillary shape. Study of this behavior is important to the understanding of effective interfaces between miscible polymer phases, which are pervasive in nature.

Foams and surfactants are relatively rare in biology because of their potential to harm cell membranes and other delicate tissues. However, in recent work we have identified and characterized a number of natural surfactant proteins found in the foam nests of tropical frogs and other unusual sources. These proteins, and their associated foams, are relatively stable and bio-compatible, but with intriguing molecular structures that reveal a new class of surfactant activity. Here we review the structures and functional mechanisms of some of these proteins as revealed by experiments involving a range of biophysical and biochemical techniques, with additional mechanistic support coming from more recent site-directed mutagenesis studies.