Good Water Dispersibility Research Articles

Modified graphene oxide/waterborne epoxy composite coating with enhanced corrosion resistance

Waterborne epoxy (WEP) resin is drawing increasing attention due to its environmentally friendly nature. However, its application has been greatly hindered by poor corrosion resistance due to its rich inherent defects. In this work, maleic acid diamine (C4H6N2O2, MAD) modified graphene oxide (M-GO) was designed as the filler, and GO/WEP composite coatings with a high cross-linking degree, improved hydrophobicity, and high barrier properties were prepared. M-GO had a good water dispersibility and high affinity to the resin. The chemical grafting between the amino group of MAD and WEP can improve the degree of chemical cross-linking inside the coating to form a compact structure. Electrochemical impedance spectroscopy (EIS) measurements and salt spray test results indicate that the M-GO/WEP composite coating with 0.3 wt% M-GO has the best anti-corrosion performance. After being immersed in 3.5 wt% NaCl solution for 96 h, the |Z|0.01Hz value of M-GO/WEP composite coating is 1.03 × 108 Ω•cm2, corrosion current density is 0.00040 ɥA/cm2 and the protection efficiency reaches 99.99 %.

Optical Graphene for Biosensor Application: A Review

One of the most often credited materials for opening up new possibilities in the creation of next-generation biosensors is graphene oxide (GO). GO has good water dispersibility, biocompatibility, and high affinity for specific biomolecules due to the coexistence of hydrophobic domains from pristine graphite structure and hydrophilic oxygen containing functional groups, as well as properties of graphene itself that are partly dependent on preparation methods. The high signal output and a strong potential for rapid industrial growth rate, graphene-based materials, such as graphene oxide (GO), are receiving substantial interest in bio sensing applications. Some of graphene's most enticing qualities are its superior conductivity and mechanical capabilities (such as toughness and elasticity), as well as its high reactivity to chemical compounds. The existence of waves on the surface (natural or created) is another property/variable that has immense potential if properly utilized. Single cell detection can be performed by optical biosensors based on graphene. The present state of knowledge about the use of graphene for bio sensing is reviewed in this article. We briefly cover the use of graphene for bio sensing applications in general, with a focus on wearable graphene-based biosensors. The intrinsic graphene ripples and their impact on graphene bio sensing capabilities are extensively examined.

Preparation of graphene oxide/polydopamine-curcumin composite nanomaterials and its antibacterial effect against Staphylococcus aureus induced by white light.

Curcumin (Cur) plays a key role in photodynamic antibacterial activity as a photosensitizer. On the other hand, the antimicrobial potential of graphene oxide (GO) has been reported controversially, and how to improve its antimicrobial ability has become an meaningful study. In this study, we prepared polydopamine-curcumin (PDA-Cur) by pi-pi stacking and loaded it onto the GO surface to obtain GO/PDA-Cur composite nanomaterials. GO/PDA-Cur was characterized by physical and optical means, and GO/PDA-Cur possessed good dispersion and stability in water. In vitro antibacterial results showed that GO/PDA-Cur mediated photodynamic therapy significantly reduced Gram-positive Staphylococcus aureus (S. aureus) by 4 orders of magnitude with a bactericidal rate of 99.99%. The antibacterial mechanism stems from the fact that GO/PDA-Cur can generate reactive oxygen species (ROS) under white light irradiation (405-780nm), which causes bacterial outer membrane breakage and cellular deformation. In addition, GO/PDA-Cur has good biocompatibility. The antibacterial ability of graphene oxide was significantly improved by combining it with PDA-Cur, which allows it to be used as a photodynamic antibacterial material.

Antifungal CoAl layered double hydroxide ultrathin nanosheets loaded with oregano essential oil for cereal preservation

Fungal infestation of cereals seriously affects human health and the economy. Protecting cereals from fungal infestation is meaningful. Therefore, safe and economical antifungal agents must be explored. Oregano essential oil (OEO) has broad-spectrum antifungal activity but is unstable and poorly water-dispersible. CoAl-LDH ultrathin nanosheets (CoAl-LDH UNs) are a biosafe carrier with peroxidase-like activity and good water dispersibility. A new nanocomposite was constructed by integrating OEO and CoAl-LDH UNs named OEO/CoAl-LDH UNs. The antifungal activity of OEO was improved for the synergetic effect of OEO and CoAl-LDH UNs. OEO/CoAl-LDH UNs showed excellent antifungal activity against Fusarium moniliforme, Fusarium graminearum and Aspergillus flavus. A polyvinyl alcohol film containing OEO/CoAl-LDH UNs was prepared as a food package and effectively inhibited fungal infestation on cereals. This work can provide some insights for the exploration of other new antifungal materials. The good biosafety of this antifungal material can be effectively applied to food packaging.

Fluorescent silver nanoclusters: from preparation to analytical application

<p indent="0mm"><b/>Owing to their excellent luminescent properties, fluorescent metal clusters show a wide range of applications in the field of analysis chemistry. Ag nanoclusters have attracted a lot of attention because of their adjustable size, good water dispersibility, biocompatibility and excellent optical properties. This review briefly summarizes the synthesis, optical properties and analytical applications of silver nanoclusters, and looks forward to the future development in this field.

Carbon dots with intrinsic theranostic properties for photodynamic therapy of oral squamous cell carcinoma.

Carbon dots (CDs) are one of the carbon-based materials with remarkable optical properties, good water dispersibility and high biocompatibility. However, few studies have emphasized the intrinsic photodynamic and anticancer properties of CDs. Herein, we used CDs as photosensitizers to explore their photodynamic therapy (PDT) effect on oral squamous cell carcinoma (OSCC) cells. The obtained CDs had an effective cellular internalization capacity and possessed good biocompatibility in both CAL-27 and UM1 cells. After irradiation, the CDs showed obvious photodynamic effects on the test cells, which were confirmed by apoptosis analysis. In addition, the CDs exhibited excellent intracellular ROS generation under irradiation, and the subsequent induced cell death may be related to a lysosome-associated pathway.

Photo-pH dual stimuli-responsive multicolor fluorescent polymeric nanoparticles for multicolor security ink, optical data encryption and zebrafish imaging

Stimuli-responsive fluorescent polymeric nanoparticles are widely used in bioimaging, anti-counterfeiting and data encryption due to their advantages of simple preparation, good water-dispersibility, high brightness and photostability. In this paper, novel photo-pH dual stimuli-responsive multicolor fluorescent polymeric nanoparticles (SMFPNs) were fabricated via combination of one-pot miniemulsion polymerization and surface modification. Based on fluorescence resonance energy transfer (FRET) principle, 4-ethoxy-9-allyl-1,8-naphthalimide (EANI), fluorescein isothiocyanate (FITC) and spiropyran-linked methacrylate (SPMA) can be used to constitute three pairs of FRET systems. In the nanoparticles, the blue fluorescence of EANI (energy donor) decreases and the green fluorescence of FITC (energy receptor) increases via increasing pH. While pH decreases, it can return to blue fluorescence. Meanwhile, after UV light irradiation, SPMA converts from non-fluorescent spiropyrans (SP) state to red fluorescent merocyanine (MC) state, the transformation from blue or green emission to red emission can be realized. When irradiated with visible light, it reverts to its original blue or green fluorescence. Therefore, the system can achieve the multi-color transformation of blue, green and red under changing pH and illumination conditions. In addition, the as-prepared nanoparticles also exhibited high fluorescence contrast, rapid photo-responsiveness and excellent photoreversibility. Therefore, SMFPNs displayed great potential in the fields of multicolor security ink, advanced anti-counterfeiting, multilevel data encryption and in vivo bioimaging.

Violet Phosphorus Quantum Dots as Distinguishable Environmental Biosensors

AbstractA molecular probe is demonstrated to be an effective semi‐invasive technique to measure the local environments of biomaterials. Environmental probes based on fluorescence intensity and lifetime are well studied as temperature sensors. However, usually both fluorescence intensity and lifetime of reported molecular probes depend on various local environments, such as temperature, pH, and ionic strength. It is a big challenge to distinguish the specific environmental effects on the fluorescence. Herein, the violet phosphorus quantum dots (VPQDs) are demonstrated to be effective fluorescence molecular probes to distinguish temperature or pH environment variation. The fluorescence intensity and bandwidth of VPQDs are demonstrated to be linearly correlated to a wide range of temperatures (283–363 K), while the fluorescence lifetime of VPQDs is demonstrated to be temperature‐independent. However, the fluorescence lifetime is demonstrated to be linearly correlated to pH value. Additionally, good water dispersibility, superior photo‐ and thermal stability, and excellent reversibility are also obtained by VPQDs. More importantly, the high sensitivity of fluorescence intensity to temperature instead of pH environments and the high sensitivity of fluorescence lifetime to pH environments instead of temperature allow VPQDs to be distinguishable biosensors to temperature and pH environments.

Universal Preparation Strategy for Ultradurable Antibacterial Fabrics through Coating an Adhesive Nanosilver Glue.

Microbiological protection textile materials played an important role in the battle against the epidemic. However, the traditional active antimicrobial treatment of textiles suffers from narrow textile applicability, low chemical stability, and poor washability. Here, a high-strength adhesive nanosilver glue was synthesized by introducing nontoxic water-soluble polyurethane glue as a protectant. The as-prepared nanosilver glue could adhere firmly to the fiber surfaces by forming a flexible polymer film and could encapsulate nanosilver inside the glue. The as-prepared nanosilver had a torispherical structure with diameter of ~22 nm, zeta potential of −42.7 mV, and good dispersibility in water, and it could be stored for one year. Further studies indicated that the nanosilver glue had wide applicability to the main fabric species, such as cotton and polyester fabric, surgical mask, latex paint, and wood paint. The antimicrobial cotton and polyester fabrics were prepared by a simple impregnation–padding–baking process. The corresponding antimicrobial activity was positively correlated with nanosilver content. The treated fabrics (500 mg/kg) exhibited ultrahigh washing resistance (maintained over 99% antibacterial rates for 100 times of standard washing) and wear resistance (99% antibacterial rates for 8000 times of standard wearing), equivalent breathability to untreated fabric, improved mechanical properties, and good flexibility, demonstrating a potential in cleanable and reusable microbiological protection textiles.

Facile Synthesis of Ag/Carbon Quantum Dots/Graphene Composites for Highly Conductive Water-Based Inks.

The development of graphene conductive inks with a high conductivity and dispersion stability in water poses considerable challenges. Herein, a highly conductive Ag/carbon quantum dots (CQDs)/graphene (G) composite with good dispersity and stability in water was prepared for the first time through the in situ photoreduction of AgNO3 and deposition of Ag onto graphene nanosheets obtained via CQD-assisted liquid-phase exfoliation. Ag nanoparticles with an average size of ∼1.88 nm were uniformly dispersed on graphene nanosheets. The Ag/CQDs/G composite exhibited good dispersity and stability in water for 30 days. The formation mechanism of the Ag/CQDs/G composites was also discussed. CQDs played a vital role in coordinating with Ag+ and reducing it under visible light conditions. The addition of only 1.58 wt % of Ag NPs to the CQDs/G film resulted in a significant decrease in the electrical resistivity by approximately 89.5%, reaching a value of 0.054 Ω cm for a 40 μm thick Ag/CQDs/G film. A low resistivity of 2.15 × 10-3 Ω cm for the Ag/CQDs/G film was achieved after rolling compression with a compression ratio of 78%. The Ag/CQDs/G film exhibited good conductivity and durability when bent, rolled, or twisted. Moreover, the resistivity of the film displayed a slight deviation after 5000 bending cycles, indicating its outstanding stability. This study provides an efficient strategy for preparing graphene-based conductive composites with good dispersibility and stability in water as well as novel high-performance conductive inks for application in flexible printed electronics.

Graphene‐Based Nucleants for Protein Crystallization

AbstractProtein crystallization remains a major bottleneck for the determination of high resolution structures. Nucleants can accelerate the process but should ideally be compatible with high throughput robotic screening. Polyethylene glycol grafted (PEGylated) graphenes can be stabilized in water providing dispensable, nucleant systems. Two graphitic feedstocks are exfoliated and functionalized with PEG using a non‐destructive, scalable, chemical reduction method, delivering good water dispersibility (80 and 750 µg mL−1 for large and small layers, respectively). The wide utility of these nucleants has been established across five proteins and three different screens, each of 96 conditions, demonstrating greater effectiveness of the dispersed PEGylated graphenes. Smaller numbers of larger, more crystalline flakes consistently act as better protein nucleants. The delivered nucleant concentration is optimized (0.1 mg mL−1 in the condition), and the performance benchmarked against existing state of the art, molecularly imprinted polymer nucleants. Strikingly, graphene nucleants are effective even when decreasing both the nucleant and protein concentration to unusually low concentrations. The set‐up to scale‐up nucleant production to liter volumes can provide sufficient material for wide implementation. Together with the optimized crystallization conditions, the results are a step forward toward practical synthesis of a readily accessible “universal” nucleant.

Synthesis and evaluation of a novel adapter lipid derivative for preparation of cyclic peptide-modified PEGylated liposomes: Application of cyclic RGD peptide

Peptide ligand modified nanoparticles can simply prepared by post-insertion method to mix pre-formed nanoparticles with peptide-lipid conjugates in an aqueous solution at an optimal temperature. Therefore, water dispersibility of peptide-lipid conjugates is a very important factor for implementing the post-insertion method. We proposed that highly water dispersible peptide-lipid conjugates can be easily synthesized by separately designing novel adapter lipids with different water dispersibility and reacting them with ligands in a highly efficient manner. Adapter lipids have three critical roles; as spacers of ligand-conjugated lipids for efficient ligand presentation, as structures that form discrete molecular weight distributions, and as providing water dispersibility. In this study, we developed a novel adapter-lipid derivative that enables a variety of cyclic peptide modifications using the click reaction. The integrin αvβ3-targeted cyclic RGDfK (cRGD) peptide was selected as the cyclic peptide ligand. We designed a novel alkyne-tagged lipid with a discrete peptide spacer and bound the cRGD peptide using a click reaction to synthesize a cRGD-conjugated lipid with good water dispersibility for the preparation of cRGD-modified PEGylated liposomes using the post-insertion method. We also revealed that cRGD-modified PEGylated liposomes are efficiently associated with integrin αvβ3-expressing murine colon carcinoma (Colon-26) cells in a modification amount- and peptide sequence-dependent manner, showing high cytotoxicity upon loading with doxorubicin. This novel adapter lipid derivative can be used to synthesize various cyclic peptides by click reactions and will provide useful insights for the future development of cyclic peptide-modified PEGylated liposomes.

Aggregation-induced emission of active nanoparticles based on konjac glucomannan: Fabrication, properties, and applications

Recently, the design of aggregation-induced emission (AIE) materials with good water-solubility and biocompatibility has attracted much attention. In this work, amphiphilic AIE-active nanoparticles (KGM-TPE) were synthesized by a facile Schiff base condensation of oxidized konjac glucomannan with amino-tetraphenylethylene. The final KGM-TPE had good water dispersibility and could self-assemble into nanoparticles with average diameters ranging from 100 to 200 nm. A cytotoxicity test showed that the cell survival was approximately 90% even when the concentration of KGM-TPE reached 150 μg/mL, indicating that KGM-TPE possessed good biocompatibility. In addition, the excellent cell imaging and good anti-counterfeiting function results of KGM-TPE indicated that this material has great potential in the fields of biomedicine and anti-counterfeiting.

Carbon Dots as Drug Delivery Vehicles for Antimicrobial Applications: A Minireview.

Carbon dots are small carbon nanoparticles with intrinsic photoluminescence. Because of the advantages such as good biocompatibility and water dispersity, many researchers have applied carbon dots as delivery platforms of antimicrobial agents. Compared with the free small-molecule antimicrobial agents alone, the carbon dot-based systems may exhibit enhanced antimicrobial activity, increased stability, improved cellular uptake, and reduced side effects. This review will mainly discuss the antimicrobial agent-loaded carbon dots for various antibacterial, antifungal, and antiviral applications. The current limitations and future research directions in the related field are also proposed. It is hoped that this review will have implications for the future development of functional carbon dots for various practical antimicrobial uses.

Engineered graphite carbon nitride for efficient elimination of indoor formaldehyde at ambient temperature

Noble-metal-free graphitic carbon nitride (g-C3N4) with a tunable bandgap has evoked great interest as a robust and efficient catalyst for environmental remediation. Herein, we prepared g-C3N4-w with good water-dispersibility via a eutectic NaCl/KCl-assisted thermal polycondensation of dicyandiamide followed by sonication-exfoliation and water-washing processes. G-C3N4-w possesses a superior performance of formaldehyde (HCHO) removal at ambient temperature to the pristine g-C3N4 obtained via direct calcination of dicyandiamide. Indoor fluorescent-lamp irradiation further upgrades the catalytic decomposition of HCHO for the g-C3N4 samples, especially for g-C3N4-w. The HCHO removal efficiency for 180 min is 66.4% and 38.5% under indoor fluorescent lamp irradiation, and 37.1% and 14.2% without light illumination for g-C3N4-w and g-C3N4, respectively. The intriguing HCHO removal capability of g-C3N4-w is contributed by its large specific surface area, abundance of defects, rapid charge transfer and extending visible-light response.

Properties of curcumin-loaded zein-tea saponin nanoparticles prepared by antisolvent co-precipitation and precipitation

The properties of nutraceutical-loaded biopolymer nanoparticles fabricated by antisolvent co-precipitation (ASCP) and precipitation (ASP) were compared. Curcumin-loaded zein-tea saponin nanoparticles were fabricated using both methods and then their structural and physicochemical properties were characterized. The diameter of the nanoparticles prepared by ASCP were smaller (120–130 nm) than those prepared by ASP (140–160 nm). The encapsulation efficiency of the ASCP-nanoparticles (80.0%) was higher than the ASP-ones (71.0%) at a zein-to-curcumin mass ratio of 3:1, which was also higher than previous studies. The storage and light stability of curcumin was higher in zein-saponin nanoparticles than in zein nanoparticles. All nanoparticles had good water dispersibility after freeze-drying and rehydration. This study shows that nanoparticles produced by antisolvent co-precipitation have superior properties to those produced by antisolvent precipitation. The co-precipitation method leads to a higher encapsulation efficiency, smaller particle size, and greater storage stability, which may be advantageous for some applications.

Aptamer functionalization and high-contrast reversible dual-color photoswitching fluorescence of polymeric nanoparticles for latent fingerprints imaging

Exploiting the intelligent stimuli-responsive fluorescent materials, which can selectively recognize lysozyme in fingerprints and enable high-contrast imaging, is still a challenge in latent fingerprints (LFPs) detection. Herein, based on Fluorescence Resonance Energy Transfer (FRET) mechanism, aptamer functionalization and high-contrast reversible dual-color photoswitching fluorescence of polymeric nanoparticles (LBA-RPFPNs) have been successfully constructed for efficient imaging of LFPs. Experiments results showed that LBA-RPFPNs displayed good water dispersibility, fast photo-responsiveness, favorable photoreversibility and good long-term stability. Of note, the aptamer possessed the ability of LBA-RPFPNs to target lysozyme in LFPs, thus realizing the selectivity of LFPs. Furthermore, the fluorescence of LBA-RPFPNs was reversibly switched between green and red through UV/visible light, achieving for high-contrast imaging of LFPs. This strategy provides good potential in disclosing the valuable information within LFPs.

Preparation of cellulose nanocrystals coated with polymer crystals and their application in composite films

AbstractIncreasing the dispersibility of cellulose nanocrystals (CNCs) as a reinforcing material is highly desirable to obtain composites with enhanced mechanical properties. To this aim, nanocomposite fibers (NCF(CNC/polymer)) were fabricated by coating CNCs with polymer crystals. Poly(vinyl alcohol) (PVA) and poly(vinyl alcohol‐co‐ethylene) (EVOH) were crystallized from a dilute solution in the presence of CNCs, which acted as nucleating agents for polymer crystal growth on the CNC surface. NCF consisting of CNCs coated with PVA crystals (NCF(CNC/PVA)) and CNCs coated with EVOH crystals (NCF(CNC/EVOH)) were successfully obtained. Both NCF(CNC/polymer) showed good dispersibility in water, even after drying, and were used to prepare composite films with improved mechanical properties. The reinforcement effect of NCF(CNC/PVA) was greater than that of pure CNCs and NCF(CNC/EVOH). The PVA composite films exhibited optical transmittance above 99% compared with additive‐free PVA films. No agglomerates appeared even under the optical microscopic observation of the PVA composite film, and NCF(CNC/PVA) dispersibility was extremely good. NCF(CNC/PVA)‐added PVA composite films exhibited increased glass transition temperature compared with additive‐free PVA films, and the crystallinity of the PVA film increased. The highly dispersed CNCs in the PVA matrix and the increase in the glass transition temperature and crystallinity caused an increase in the mechanical modulus of the PVA composite film at low NCF(CNC/PVA) content. Furthermore, the effect of the morphologies of cellulose nanofibers and CNCs on the mechanical properties of the composite films prepared using the respective NCFs was investigated.

Water-Dispersible Porous Aromatic Frameworks with Quasi-Amino Acid Structures via N-H Insertion Reactions.

As a class of materials with large specific surface area and chemical stability, porous aromatic frameworks (PAFs) have attracted much attention in the fields of gas adsorption, separation, and catalysis. However, synthetic methods for PAFs have been limited to a few coupling reactions, and PAF powders were usually obtained with a diameter of micrometer size. Here, we demonstrate an efficient N-H insertion reaction of diazoesters in the synthesis of PAFs with a diameter <200 nm. The established polymerization can be performed at room temperature, and four PAFs with different skeletons and composition can be obtained in high yields. The prepared PAFs have appreciable thermal and chemical stabilities. Because of the presence of ester groups in the backbone, the prepared PAFs with α-phenylglycine fragments can be easily obtained through the successive hydrolysis of the ester groups. The synthesized PAFs bearing phenylglycine moieties exhibit good water dispersibility and low cytotoxicity. We further show the potential of these PAFs in drug loading and photodynamic therapy.

Pyrene-based sulfonated organic porous materials for rapid adsorption of cationic dyes in water

ABSTRACT Porous organic polymers (POP) have gained attention because of their high specific surface area, porosity and their simplicity in synthesis, but for the most part, they are hydrophobic because of their organic backbone, making it difficult to expand their applications. Here, we have obtained poly(pyrene) porous organic polymers (PyPOP) through the polymerization of pyrene monomers catalysed by aluminium trichloride, which is a simple and inexpensive synthesis method. The sulfonated poly(pyrene) porous organic polymers (PyPOP-SO3H) obtained showed rapid adsorption of cationic dyes, especially malachite green (MG adsorption 1607 mg/g) and methylene blue (MB adsorption 1220 mg/g) in pH = 7 aqueous solution, room temperature. The results show that the Freundlich model is more in line with the adsorption process than the Langmuir model, whether for methylene blue or malachite green. In addition, the PSO kinetic model fits better than PFO kinetic model, whether it is for the adsorption of methylene blue or malachite green. The excellent adsorption performance of PyPOP-SO3H for cationic dyes may be due to the introduction of sulfonic acid groups, which not only increases the specific surface area but also allows better dispersion in water, increasing contact points and adsorption efficiency. This research expands the scope of exploration and application of POP.