Photo-degradable and recyclable starch/Fe3O4/TiO2 nanocomposites: feasibility of an approach to reduce the recycling labor cost in plastic waste management

In this research, a biodegradable starch/Fe₃O₄/TiO₂ bio-nanocomposites (SFT) were produced using different nano Fe₃O₄/TiO₂ (FT) (3, 5, and 10 (wt% dry based)) contents. Mechanical properties, visual properties, moisture-sensitive parameters, magnetic properties, and physical properties of the film specimens were investigated. Photodegradability of film specimens was also evaluated under UV-A irradiation. The FT content increased the hydrophobicity of the film specimens. Tensile strength (TS) of SFT films was increased by increasing FT up to 3%. Elongation at break (EB) and tensile energy to break (TEB) were decreased by adding FT content up to 3% simultaneously. The film specimens' water vapor permeability (WVP) was decreased with increasing FT content. The intrinsic viscosity of SFT was decreased by increasing FT content. It confirms the enhancement of photodegradability of the specimens by increasing FT content. It seems the compatibility of FT with biopolymer has had great effects on these properties. Use of FT-based nanocomposites is an appropriate approach to developing magnetic-recyclable and photodegradable packaging materials.

3D-Printed Multifunctional Polyetheretherketone Bone Scaffold for Multimodal Treatment of Osteosarcoma and Osteomyelitis

In this work, we developed the first 3D-printed polyetheretherketone (PEEK)-based bone scaffold with multi-functions targeting challenging bone diseases such as osteosarcoma and osteomyelitis. A 3D-printed PEEK/graphene nanocomposite scaffold was deposited with a drug-laden (antibiotics and/or anti-cancer drugs) hydroxyapatite coating. The graphene nanosheets within the scaffold served as effective photothermal agents that endowed the scaffold with on-demand photothermal conversion function under near-infrared laser irradiation. The bioactive hydroxyapatite coating significantly boosted the stem cell proliferation in vitro and promoted new bone growth in vivo. The presence of antibiotics and anti-cancer drugs enabled eradication of drug-resistant bacteria and ablation of osteosarcoma cancer cells, the treatment efficacy of which can be further enhanced by on-demand laser-induced heating. The promising results demonstrate the strong potential of our multi-functional scaffold in applications such as bone defect repair and multimodal treatment of osteosarcoma and osteomyelitis.

Triformyl cholic acid and folic acid functionalized magnetic graphene oxide nanocomposites: Multiple-targeted dual-modal synergistic chemotherapy/photothermal therapy for liver cancer

Photo-chemotherapy (PCT) reveals great potential in hepatocellular carcinoma (HCC) treatment, therefore the construct of smart PCT nano-agents with high photothermal conversion efficiency and accurate drug delivery is of great significant. Herein, a novel hybrid nanomaterial MGO-TCA-FA has been designed and constructed by grafting the triformyl cholic acid (TCA) and folic acid (FA) on the surface of Fe3O4 modified graphene oxide (MGO). The doxorubicin hydrochloride (DOX) as a model drug could be effectively loaded on the MGO-TCA-FA via hydrogen bonding and π-π stacking (the drug loading amount was 1040 mg/g). The formed MGO-TCA-FA@DOX has been developed to be an effective PCT nanoplatform with the advantages of multiple-targeted drug delivery, near-infrared light (NIR) and pH triggered drug release, and photothermal conversion efficiency. In vitro experiments showed that compared with other cancer cells and normal liver cells, MGO-TCA-FA@DOX could specifically target liver cancer cells and presented significant killing ability to liver cancer cells. More importantly, in vivo experiments indicated that PCT synergistic therapy (MGO-TCA-FA@DOX) revealed the best tumor inhibition (the tumor inhibition rate was about 85%) compared with chemotherapy and photothermal therapy alone. Thus, this study supplied a viable multiple-targeted PCT nano-agent for chemo-photothermal combination therapy of liver cancer.

Synergistic Multimodal Cancer Therapy Using Glucose Oxidase@CuS Nanocomposites

Multimodal nanotherapeutic cancer treatments are widely studied but are often limited by their costly and complex syntheses that are not easily scaled up. Herein, a simple formulation of glucose-oxidase-coated CuS nanoparticles was demonstrated to be highly effective for melanoma treatment, acting through a synergistic combination of glucose starvation, photothermal therapy, and synergistic advanced chemodynamic therapy enabled by near-infrared irradiation coupled with Fenton-like reactions that were enhanced by endogenous chloride.

Photomechanical Polymer Nanocomposites for Drug Delivery Devices

We demonstrate a novel structure based on smart carbon nanocomposites intended for fabricating laser-triggered drug delivery devices (DDDs). The performance of the devices relies on nanocomposites' photothermal effects that are based on polydimethylsiloxane (PDMS) with carbon nanoparticles (CNPs). Upon evaluating the main features of the nanocomposites through physicochemical and photomechanical characterizations, we identified the main photomechanical features to be considered for selecting a nanocomposite for the DDDs. The capabilities of the PDMS/CNPs prototypes for drug delivery were tested using rhodamine-B (Rh-B) as a marker solution, allowing for visualizing and quantifying the release of the marker contained within the device. Our results showed that the DDDs readily expel the Rh-B from the reservoir upon laser irradiation and the amount of released Rh-B depends on the exposure time. Additionally, we identified two main Rh-B release mechanisms, the first one is based on the device elastic deformation and the second one is based on bubble generation and its expansion into the device. Both mechanisms were further elucidated through numerical simulations and compared with the experimental results. These promising results demonstrate that an inexpensive nanocomposite such as PDMS/CNPs can serve as a foundation for novel DDDs with spatial and temporal release control through laser irradiation.

Near-Infrared Radiation-Assisted Drug Delivery Nanoplatform to Realize Blood-Brain Barrier Crossing and Protection for Parkinsonian Therapy

Mitochondrial dysfunction, which is directly involved in Parkinson's disease (PD), is characterized by the production of reactive oxygen species (ROS) and aberrant energy metabolism. Thus, regulating mitochondrial function might be an effective strategy to treat PD. However, the blood-brain barrier (BBB) presents a significant challenge for the intracerebral delivery of drugs. Here, we synthesized a zeolitic imidazolate framework 8-coated Prussian blue nanocomposite (ZIF-8@PB), which was encapsulated with quercetin (QCT), a natural antioxidant, to treat PD. ZIF-8@PB-QCT exhibited superior near-infrared radiation (NIR) response and penetrated through the BBB to the site of mitochondrial damage guided by the photothermal effect. In the mice model of PD, the QCT released from ZIF-8@PB-QCT significantly increased the adenosine triphosphate levels, reduced the oxidative stress levels, and reversed dopaminergic neuronal damage as well as PD-related behavioral deficits without any damage to the normal tissues. Furthermore, we explored the underlying neuroprotective mechanism of ZIF-8@PB-QCT that was mediated by activating the PI3K/Akt signaling pathway. Thus, combined with noninvasive NIR radiation, the biocompatible ZIF-8@PB-QCT nanocomposite could be used to treat neurodegenerative diseases.

Fluorescent detection of microRNA-21 in MCF-7 cells based on multifunctional gold nanorods and the integration of chemotherapy and phototherapy

MicroRNA-21 is an important biomarker of tumor early prediction and metastasis, and its accurate detection is of great significance for tumor diagnosis and treatment. It will be a meaningful work to combine the detection of RNA with chemotherapy and photothermal therapy on the same composite material. Herein, we designed a multifunctional nanocomposite based on gold nanorods (AuNRs), making use of microRNA-triggered drug release and near-infrared photothermal effect, which has been developed for cancer therapy and microRNA-21detection. Firstly, the AuNRs with photothermal effect were synthesized as carriers for drug delivery. Then the surface of gold nanorods was modified by functional DNA chains to provide an efficient site for doxorubicin (DOX) loading. Finally, folic acid was introduced to achieve the targeted treatment of MCF-7 cells. The microRNA competed with the double-stranded DNA, resulting in the release of DOX and the recovery of fluorescence signal located at 595 nm with an excitation of 488 nm effectively. The nano-biosensor could not only achieve dual-function of diagnosis and treatment of cancer cells, but also accomplish the detection of microRNA in tumor cells. It showed a high selectivity for microRNA-21 determination with a limit of detection (LOD) of 2.1 nM from the linear relationship from 1.0 × 10^-5 M to 5.0 × 10^-7 M. This scheme provides an outstanding strategy for cell imaging, treatment, and detection, which serves as a promising candidate in the field of biomedical research.

Synergistic Photodynamic and Photothermal Antibacterial Activity of In Situ Grown Bacterial Cellulose/MoS2-Chitosan Nanocomposite Materials with Visible Light Illumination

Owing to the rise in prevalence of multidrug-resistant pathogens attributed to the overuse of antibiotics, infectious diseases caused by the transmission of microbes from contaminated surfaces to new hosts are an ever-increasing threat to public health. Thus, novel materials that can stem this crisis, while also functioning via multiple antimicrobial mechanisms so that pathogens are unable to develop resistance to them, are in urgent need. Toward this goal, in this work, we developed in situ grown bacterial cellulose/MoS₂-chitosan nanocomposite materials (termed BC/MoS₂-CS) that utilize synergistic membrane disruption and photodynamic and photothermal antibacterial activities to achieve more efficient bactericidal activity. The BC/MoS₂-CS nanocomposite exhibited excellent antibacterial efficacy, achieving 99.998% (4.7 log units) and 99.988% (3.9 log units) photoinactivation of Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus, respectively, under visible-light illumination (xenon lamp, 500 W, λ ≥ 420 nm, and 30 min). Mechanistic studies revealed that the use of cationic chitosan likely facilitated bacterial membrane disruption and/or permeability, with hyperthermia (photothermal) and reactive oxygen species (photodynamic) leading to synergistic pathogen inactivation upon visible-light illumination. No mammalian cell cytotoxicity was observed for the BC/MoS₂-CS membrane, suggesting that such composite nanomaterials are attractive as functional materials for infection control applications.

Albumin-Templated Bi2Se3-MnO2 Nanocomposites with Promoted Catalase-Like Activity for Enhanced Radiotherapy of Cancer

Novel and effective radiosensitizers that can enhance radiosensitivity of tumor tissues and increase the local radiation dose are highly desirable. In this work, templated by bovine serum albumin (BSA), Bi2Se3-MnO2 nanocomposites (Bi2Se3-MnO2@BSA) were fabricated via biomineralization, while Bi2Se3 nanodots act as radiosensitizers to increase the local radiation dosage because of their strong X-ray attenuation ability, and MnO2 with catalase-like activity can increase the oxygen concentration in tumors by triggering the decomposition of tumor endogenous H2O2 so as to improve the hypoxia-associated radioresistance of tumors. Owing to the interaction of the two components in the interface, Bi2Se3-MnO2@BSA showed promoted catalytic activity compared to MnO2@BSA, favoring tumor radiotherapy (RT) sensitization. BSA templating enabled the nanocomposites with high colloidal stability and biocompatibility as well as satisfactory tumor targeting both in vitro and in vivo; thus, an enhanced RT efficacy was obtained. Moreover, the proposed Bi2Se3-MnO2@BSA exhibited excellent performances in computerized tomography and magnetic resonance imaging. Thus, this work provides a tumor microenvironment-responsive multifunctional theranostic nanoagent with an improved performance for imaging-guided tumor RT sensitization.

Novel Core-Sheath Cu/Cu2O-ZnO-Fe3O4 Nanocomposites with High-Efficiency Chlorine-Resistant Bacteria Sterilization and Trichloroacetic Acid Degradation Performance

In order to solve two issues of chlorine-resistant bacteria (CRB) and disinfection byproducts (DBPs) in tap water after the chlorine-containing treatment process, an innovative core-sheath nanostructured Cu/Cu₂O-ZnO-Fe₃O₄ was designed and synthesized. The fabrication mechanism of the materials was then systematically analyzed to determine the component and valence state. The properties of CRB inactivation together with trichloroacetic acid (TCAA) photodegradation by Cu/Cu₂O-ZnO-Fe₃O₄ were investigated in detail. It was found that Cu/Cu₂O-ZnO-Fe₃O₄ displayed excellent antibacterial activity with a relatively low cytotoxicity concentration due to its synergism of nanowire structure, ion release, and reactive oxygen species generation. Furthermore, the Cu/Cu₂O-ZnO-Fe₃O₄ nanocomposite also exhibited outstanding photocatalytic degradation activity on TCAA under simulated sunlight irradiation, which was verified to be dominated by the surface reaction through kinetic analysis. More interestingly, the cell growth rate of Cu/Cu₂O-ZnO-Fe₃O₄ was determined to be 50% and 10% higher than those of Cu/Cu₂O and Cu/Cu₂O-ZnO after 10 h incubation, respectively, manifesting a weaker cytotoxicity. Therefore, the designed Cu/Cu₂O-ZnO-Fe₃O₄ could be a promising agent for tap water treatment.

NIR-Driven Intracellular Photocatalytic O2 Evolution on Z-Scheme Ni3S2/Cu1.8S@HA for Hypoxic Tumor Therapy

Hypoxia in a tumor microenvironment (TME) has inhibited the photodynamic therapy (PDT) efficacy. Here, Ni₃S₂/Cu_1.8S nanoheterostructures were synthesized as a new photosensitizer, which also realizes the intracellular photocatalytic O₂ evolution to relieve hypoxia in TME and enhance PDT as well. With the narrow band gap (below 1.5 eV), the near infrared (NIR) (808 nm) can stimulate their separation of the electron-hole. The novel Z-scheme nanoheterostructures, testified by experimental data and density functional theory (DFT) calculation, possess a higher redox ability, endowing the photoexited holes with sufficient potential to oxide H₂O into O₂, directly. Meanwhile, the photostimulated electrons can capture the dissolved O₂ to form a toxic reactive oxygen species (ROS). Moreover, Ni₃S₂/Cu_1.8S nanocomposites also possess the catalase-/peroxidase-like activity to convert the endogenous H₂O₂ into ·OH and O₂, which not only cause chemodynamic therapy (CDT) but also alleviate hypoxia to assist the PDT as well. In addition, owing to the narrow band gap, they possess a high NIR harvest and great photothermal conversion efficiency (49.5%). It is noted that the nanocomposites also exhibit novel biodegradation and can be metabolized and eliminated via feces and urine within 2 weeks. The present single electrons in Ni/Cu ions induce the magnetic resonance imaging (MRI) ability for Ni₃S₂/Cu_1.8S. To make sure that the cancer cells were specifically targeted, hyaluronic acid (HA) was grafted outside and Ni₃S₂/Cu_1.8S@HA integrated photodynamic therapy (PDT), chemodynamic therapy (CDT), and photothermal therapy (PTT) to exhibit the great anticancer efficiency for hypoxic tumor elimination.

A novel ternary heterogeneous TiO2/BiVO4/NaY-Zeolite nanocomposite for photocatalytic degradation of microcystin-leucine arginine (MC-LR) under visible light

Microcystin-leucine arginine (MC-LR) is a carcinogenic toxin, produced by cyanobacteria. The release of this toxin into drinking water sources can threaten public health and environmental safety. Therefore, effective MC-LR removal from water resources is necessary. In the present study, the hydrothermal method was used to synthesize a novel ternary BiVO₄/TiO₂/NaY-Zeolite (B/T/N-Z) nanocomposite for MC-LR degradation under visible light. FESEM, FTIR, XRD, and DRS were performed for characterizing the nanocomposite structure. Also, the Response Surface Methodology (RSM) was applied to determine the impact of catalyst dosage, pH, and contact time on the MC-LR removal. High-performance liquid chromatography was performed to measure the MC-LR concentration. Based on the results, independent parameters, including contact time, catalyst dosage, and pH, significantly affected the MC-LR removal (P < 0.05). In other words, increasing the contact time, catalyst dosage, and acidic pH had positive effects on MC-LR removal. Among these variables, the catalyst dosage, with the mean square and F-value of 1041.37 and 162.84, respectively, had the greatest effect on the MC-LR removal efficiency. Apart from the interaction between the catalyst dosage and contact time, the interaction effects of other parameters were not significant. Also, the maximum MC-LR removal efficiency was 99.88% under optimal conditions (contact time = 120 min, catalyst dosage = 1 g/L, and pH = 5). According to the results, the B/T/N-Z nanocomposite, as a novel and effective photocatalyst could be used to degrade MC-LR from polluted water.

Evaluation of degree of conversion, rate of cure, microhardness, depth of cure, and contraction stress of new nanohybrid composites containing pre-polymerized spherical filler

The aim of the present study was to characterize nanohybrid and nanofilled composites in terms of degree of conversion (DC), rate of cure (RC), microhardness (Vickers hardness number; VHN), depth of cure, and contraction stress (CS). Ceram.X® universal- A3, duo enamel E2, and duo dentin D3 composites were compared to Tetric EvoCeram® and FiltekTMSupreme XTE composites of equivalent dentin and enamel shades under a 40 s photopolymerization protocol. DC was measured by infrared spectroscopy, calculating RC from the kinetic curve. Top and bottom VHN were determined using a Vickers indenter, and bottom/top surface ratio (Vickers hardness ratio; VHR) calculated. CS vs. time was assessed by a universal testing machine and normalized for the specimen bonding area. All materials showed DC  < 60%, Ceram.X® composites reaching higher values than the other composites of corresponding shades. RC at 5 s of photopolymerization was always higher than that at 10 s. All the Ceram.X® composites and the lighter-shaded Tetric EvoCeram® and FiltekTMSupreme XTE composites reached the RC plateau after 25 s, the remaining materials showed a slower kinetic trend. Tetric EvoCeram® and FiltekTMSupreme XTE composites displayed the softest and the hardest surfaces, respectively. Differently from darker-shaded materials, the universal and the three enamel-shaded composites resulted optimally cured (VHR >  80%). The tested composites differed in CS both during and after light cure, Tetric EvoCeram® and FiltekTMSupreme XTE composites displaying the highest and the lowest CS, respectively. Only the Ceram.X® universal-A3 reached a CS plateau value. The tested composites exhibited material-dependent chemo-mechanical properties. Increasing the curing time and/or reducing the composite layer thickness for dentin-shaded composites appears advisable.

The Response of Pseudomonas aeruginosa PAO1 to UV-activated Titanium Dioxide/Silica Nanotubes

Pseudomonas aeruginosa is a bacterium of high clinical and biotechnological importance thanks to its high adaptability to environmental conditions. The increasing incidence of antibiotic-resistant strains has created a need for alternative methods to increase the chance of recovery in infected patients. Various nanomaterials have the potential to be used for this purpose. Therefore, we aimed to study the physiological response of P. aeruginosa PAO1 to titanium dioxide/silica nanotubes. The results suggest that UV light-irradiated nanomaterial triggers strong agglomeration in the studied bacteria that was confirmed by microscopy, spectrophotometry, and flow cytometry. The effect was diminished when the nanomaterial was applied without initial irradiation, with UV light indicating that the creation of reactive oxygen species could play a role in this phenomenon. The nanocomposite also affected biofilm formation ability. Even though the biomass of biofilms was comparable, the viability of cells in biofilms was upregulated in 48-hour biofilms. Furthermore, from six selected genes, the mexA coding efflux pump was upregulated, which could be associated with an interaction with TiO2. The results show that titanium dioxide/silica nanotubes may alter the physiological and metabolic functions of P. aeruginosa PAO1.

Novel CoFe2O4@ZnO-CeO2 ternary nanocomposite: Sonochemical green synthesis using Crataegus microphylla extract, characterization and their application in catalytic and antibacterial activities

In this study, CoFe₂O₄@ZnO-CeO₂ magnetic nanocomposite (CoFe@Zn-Ce MNC) was successfully prepared by facile sonochemical method for the first time. CoFe@Zn-Ce MNC was obtained by green and cost-effective process in the presence of Crataegus microphylla (C. microphylla) fruit extract. Influence of some parameters like capping agents (C. microphylla, SDS and CTAB), sonication time (10, 30 and 60 min) and sonication power (40, 60 and 80 W) were studied to achieve optimum condition. The as-obtained products were characterized by FT-IR, FESEM, TEM, DRS, VSM, EDS, TGA and XRD analysis. Results showed that high magnetic properties (20.38 emug^-1), 70-80 nm size and spherical morphology were unique characteristics of synthesized nanocomposite. Antibacterial activity of CoFe@Zn-Ce MNC was examined against E. coli, P. aeruginoss and S. aureus bacteria. Among theme, S. aureus as gram-positive bacteria showed excellent antibacterial activity. Furthermore, photocatalytic performance of the CoFe@Zn-Ce MNC was investigated by degradation of humic acid (HA) molecules under visible and UV light irradiations. The influence of morphology of products and incorporation of cerium oxide with CoFe₂O₄@ZnO on photocatalytic activity of CoFe₂O₄@ZnO was performed. After 100 min illumination, the decomposition of HA pollutant by magnetic nanocomposite were 97.2% and 72.4% under exposure of UV and visible light irradiations, respectively. Also, CoFe@Zn-Ce MNC demonstrated high stability in the cycling decomposition experiment after six times cycling runs.

Photothermal graphene/UiO-66-NH2 fabrics for ultrafast catalytic degradation of chemical warfare agent simulants

Lightweight and wearable fabrics with rapid self-detoxification functions are highly desired to resist chemical warfare agents (CWAs). Metal organic frameworks (MOFs) with high specific surface area and customizability are singularly attractive because of their ability to effectively capture and catalytically degrade CWAs. Herein, photothermal graphene-based nanocomposite fabrics are designed by wet-spinning and chemical reduction of graphene oxide fibers followed by in situ growth of UiO-66-NH₂. The flexible graphene fabrics decorated with UiO-66-NH₂ nanoparticles exhibit an ultrafast photothermal catalytic decontamination of dimethyl 4-nitrophenyl phosphate (DMNP), a typical simulant of CWAs. The half-life of the degradation reaction decreases from 3.4 to 1.6 min under simulated solar light irradiation, a significant gain over the values reported in the literature. Furthermore, DMNP can be degraded in 20 min by the graphene/UiO-66-NH₂ fabric, and even after 5 cycles the degradation efficiency still retains more than 92 %. More importantly, the photothermal conversion of graphene and its instantaneous heat transfer to the UiO-66-NH₂ catalyst effectively accelerate the catalytic reaction kinetics, achieving the fast detoxification of DMNP. The combination of catalytic degradation of MOFs with photothermal conversion effect of graphene makes the lightweight and flexible fabrics promising for protection against CWAs and other pollutants.

A trade-off between adsorption and photocatalysis over ZIF-derived composite

The adsorption with highly porous adsorbents is an efficient technique to trap the uncontrolled release of antibiotics in the environment, however, mere adsorption does not mineralize the discharged antibiotics. On the contrary, the regular photocatalysts completely mineralize the antibiotics, however suffers from high efficiency due to comparatively low surface area and porosity. In this work, a balance has been made between efficient adsorption followed by complete degradation of the adsorbed antibiotic over ZIF-8 derived ZnO/N-doped carbon composite. The nitrogen-doped carbon produced at 1000 °C showed a very high adsorption capacity of SMX, due to higher surface area, porosity and better surface interaction between adsorbate and adsorbent. The ZnO formed at 600 °C produced sufficient OH· that were responsible to show a very high rate of complete photocatalytic mineralization of SMX over the material. The ZnO/N-doped carbon composite showed a very high rate of photodegradation with a corresponding rate constant of 4.36 × 10^-2 min^-1. The complete degradation mechanism was proposed and rates were compared with existing literature.

Carbon Nanotube Reinforced High Density Polyethylene Materials for Offshore Sheathing Applications

Multiwall carbon nanotube (CNT)-filled high density polyethylene (HDPE) nanocomposites were prepared by extrusion and considered for their suitability in the offshore sheathing applications. Transmission electron microscopy was conducted to analyse dispersion after bulk extrusion. Monolithic and nanocomposite samples were subjected to accelerated weathering and photodegradation (carbonyl and vinyl indices) characterisations, which consisted of heat, moisture (seawater) and UV light, intended to imitate the offshore conditions. The effects of accelerated weathering on mechanical properties (tensile strength and elastic modulus) of the nanocomposites were analysed. CNT addition in HDPE produced environmentally resilient nanocomposites with improved mechanical properties. The energy utilised to extrude nanocomposites was also less than the energy used to extrude monolithic HDPE samples. The results support the mass substitution of CNT-filled HDPE nanocomposites in high-end offshore applications.

High selectivity and effectiveness for removal of tetracycline and its related drug resistance in food wastewater through schwertmannite/graphene oxide catalyzed photo-Fenton-like oxidation

Selectively and effectively for removal of tetracycline (TC) and its related antibiotic resistance gene from food wastewater matrix with high-salt and high COD characteristics is highly desirable. In this work, novel schwertmannite/graphene oxide (SCH/GO) nanocomposites were synthesized through a facile oxidation-coprecipitation method. The SCH/GO nanocomposites were characterized by TEM, XRD, BET, PL, DRS, XPS and FTIR. In the presence of 1 mM H₂O₂, the SCH/GO catalyzed Fenton-like oxidation can thoroughly degrade TC under visible light irradiation, even under nature sunlight, whose second-order kinetic rate constant was about 15 times higher than that of pure SCH. SCH/GO was capable of highly selectively capturing and effectively degrading TC in the presence of similar concentration of Cl^-, NO₃^-, SO₄^2- and PO₄^3- with that of food wastewater, even at organic matters concentration of 12.5 times than that of TC. At the same time, the removal of total organic carbon (TOC) and chemical oxygen demand (COD) in aforementioned food wastewater in SCH/GO+H₂O₂+Vis system reached 27.3 % and 34.5 % after 60 min, respectively. The inhibition zone experiments authenticated that the removal of drug resistance of bacteria by TC degradation intermediates can be achieved very well without producing secondary contamination in this system.

Halloysite/Keratin Nanocomposite for Human Hair Photoprotection Coating

We propose a novel keratin treatment of human hair by its aqueous mixtures with natural halloysite clay nanotubes. The loaded clay nanotubes together with free keratin produce micrometer-thick protective coating on hair. First, colloidal and structural properties of halloysite/keratin dispersions and the nanotube loaded with this protein were investigated. Above the keratin isoelectric point (pH = 4), the protein adsorption into the positive halloysite lumen is favored because of the electrostatic attractions. The ζ-potential magnitude of these core-shell particles increased from -35 (in pristine form) to -43 mV allowing for an enhanced colloidal stability (15 h at pH = 6). This keratin-clay tubule nanocomposite was used for the immersion treatment of hair. Three-dimensional-measuring laser scanning microscopy demonstrated that 50-60% of the hair surface coverage can be achieved with 1 wt % suspension application. Hair samples have been exposed to UV irradiation for times up to 72 h to explore the protection capacity of this coating by monitoring the cysteine oxidation products. The nanocomposites of halloysite and keratin prevent the deterioration of human hair as evident by significant inhibition of cysteic acid. The successful hair structure protection was also visually confirmed by atomic force microscopy and dark-field hyperspectral microscopy. The proposed formulation represents a promising strategy for a sustainable medical coating on the hair, which remediates UV irradiation stress.

Polypyrrole and polyaniline nanocomposites with high photothermal conversion efficiency

The simple and scalable synthesis of poly[2-(methacryloyloxy)ethyl phosphorylcholine] (PMPC)-coated conducting polymer (CP) nanocomposites is described. These functional nanocomposites exhibit tunable absorption in the near-infrared region with relatively high photothermal efficiencies. More importantly, their potential for bio-imaging and therapeutic treatment is proven by cellular uptake and cytotoxicity studies.

Sono-photocatalytic degradation of tetracycline and pharmaceutical wastewater using WO3/CNT heterojunction nanocomposite under US and visible light irradiations: A novel hybrid system

In this paper, in-situ fabrication of tungsten oxide (WO₃) on carbon nano-tube (CNT) was performed via sol-gel/hydrothermal method to prepare WO₃/CNT nanocomposites and then coupled with visible light and ultrasound (US) irradiations for sono-photocatalytic removal of tetracycline (TTC) and pharmaceutical wastewater treatment. The as-prepared catalysts were characterized by FT-IR, XRD, TEM, UV-VIS DRS, FESEM, EDS, TGA, BET, BJH, EIS, and EDX techniques. The characterization tests, indicated successful incorporation of CTNs into the WO₃ framework and efficient reduction of charge carries recombination rate after modifying with CNT. The investigation of experimental parameters verified that 60 mg/L TTC could be perfectly degraded at optimum operational parameters (WO₃/CNT: 0.7 g/L, pH: 9.0, US power: 250 W/m², and light intensity: 120 W/m² over 60 min treatment. Trapping experiments results verified that HO radicals and h⁺ were the main oxidative species in degradation of TTC. The as-prepared photocatalysts could be reused after six successive cycles with an approximately 8.8 % reduction in removal efficiency. Investigation of the effect of real pharmaceutical wastewater revealed that this system is able to eliminate 83.7 and 90.6 % of TOC and COD, respectively after 220 min of reaction time. Some compounds with lower toxic impact and molecular weight, compared to raw pharmaceutical wastewater, were detected after treatment by sono-photocatalysis process. The biodegradability of real pharmaceutical wastewater was improved significantly after treatment by WO₃/CNT sono-photocatalysis.

Dual Pathway for Promotion of Stem Cell Neural Differentiation Mediated by Gold Nanocomposites

The neural differentiation of embryonic stem cells (ESCs) is of great value in the treatment of neurodegenerative diseases. On the basis of the two related signaling pathways that direct the neural differentiation of ESCs, we used gold nanoparticles (GNP) as a means of combining chemical and physical cues to trigger the neurogenic differentiation of stem cells. Neural differentiation-related functional units (glyco and sulfonate units on glycosaminoglycans, GAG) were anchored on the GNP surface and were then transferred to the cell membrane surface via GNP-membrane interactions. The functional units were able to activate the GAG-related signaling pathway, in turn promoting differentiation and maturation of stem cells into neuronal lineages. In addition, using the photothermal effect of GNP, the differentiation-inducing factor retinoic acid (RA), could be actively delivered into cells via laser irradiation. The RA-related intracellular signaling pathway was thereby further triggered, resulting in strong promotion of neurogenesis with a 300-fold increase in mature neural marker expression. The gold nanocomposites developed in this work provide the basis for a new strategy directing ESCs differentiation into nerve cells with high efficiency and high purity by acting on two related signaling pathways.

Facile fabrication of silver iodide/graphitic carbon nitride nanocomposites by notable photo-catalytic performance through sunlight and antimicrobial activity

Silver iodide/graphitic carbon nitride nanocomposites have been successfully fabricated through sonication-assisted deposition-precipitation route at room temperature and hydrothermal method. Varied mass ratios and preparation processes can modify the structure, purity, shape, and scale of specimens. The purity of the product was confirmed by Energy Dispersive X-Ray Spectroscopy (EDS) and X-ray crystallography. The morphology and size of specimens could be observed with transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM). The bandgap was evaluated around 2.82 eV for pure g-C₃N₄. The bandgap has reduced to 2.70 eV by increasing the quantity of silver iodide in the nanocomposites. The photocatalytic activity of AgI/C₃N₄ has been studied over the destruction of rhodamine B (RhB) and methyl orange (MO) through visible radiation due to their suitable bandgap. The as-prepared AgI/C₃N₄ nanocomposites photocatalyst revealed better photocatalytic behavior than the genuine AgI and C₃N₄ which ascribed to synergic impacts at the interconnection of C₃N₄ and AgI. Furthermore, these nanocomposites have great potential for being a great antibacterial agent.

Optimising FRET-efficiency of Nd3+-sensitised upconversion nanocomposites by shortening the emitter-photosensitizer distance

Nd3+-Sensitised luminescent upconversion nanoparticles (UCNPs) have gained interest recently as theranostics due to their near-infrared (NIR) light excitation with a better tissue penetration depth. One example is the core/shell design NaYF4:Yb,Er@Nd,Yb. When harvesting the upconversion energy in such architectures, the long emitter-photosensitizer (i.e. Er3+-PS) distances lead to inefficient Förster resonance energy transfer (FRET). Herein, we report a new nanocomposite NaYF4:Nd,Yb@Yb@Yb,Er@Y with Nd3+ ions in the core and Er3+ ions in the shell to shorten the Er-PS distance to achieve better FRET. Furthermore, an outer non-emitting protective Y3+ shell and a conducting Yb3+ shell reduced surface quenching and Er3+-to-Nd3+ energy back transfer effects, respectively. The upconversion FRET and downshifting emission efficiencies were simultaneously optimised by adjusting the thickness of the Y3+ shell, and the FRET efficiency was at least 3.7 times that of the reference NaYF4:Yb,Er@Yb@Nd,Yb@Y in a photodynamic therapy (PDT) model.

Self-Sufficient and Highly Efficient Gold Sandwich Upconversion Nanocomposite Lasers for Stretchable and Bio-applications

Multifunctional lanthanide-doped upconversion nanoparticles (UCNPs) have spread their wings in the fields of flexible optoelectronics and biomedical applications. One of the ongoing challenges lies in achieving UCNP-based nanocomposites, which enable a continuous-wave (CW) laser action at ultralow thresholds. Here, gold sandwich UCNP nanocomposites [gold (Au¹)-UCNP-gold (Au²)] capable of exhibiting lasing at ultralow thresholds under CW excitation are demonstrated. The metastable energy-level characteristics of lanthanides are advantageous for creating population inversion. In particular, localized surface plasmon resonance-based electromagnetic hotspots in the nanocomposites and the huge enhancement of scattering coefficient for the formation of coherent closed loops due to multiple scattering facilitate the process of stimulated emissions as confirmed by theoretical simulations. The nanocomposites are subjected to stretchable systems for enhancing the lasing action (threshold ∼ 0.06 kW cm^-2) via a light-trapping effect. The applications in bioimaging of HeLa cells and antibacterial activity (photothermal therapy) are demonstrated using the newly designed Au¹-UCNP-Au² nanocomposites.

Gold nanobipyramid-loaded black phosphorus nanosheets for plasmon-enhanced photodynamic and photothermal therapy of deep-seated orthotopic lung tumors

Various types of photodynamic agents have been explored for photodynamic therapy (PDT) to destroy cancers located in deep tissues. However, these agents are generally limited by low singlet oxygen (¹O₂) yields owing to weak absorption in the optical transparent window of biological tissues. Accordingly, in this work, we developed a nanocomposite through the assembly of gold nanobipyramids (GNBPs) on black phosphorus nanosheets (BPNSs). This nanocomposite could simultaneously enhance ¹O₂ generation and hyperthermia by localized surface plasmon resonance in cancer therapy. As two-dimensional inorganic photosensitizers, BPNSs were hybridized with GNBPs to form BPNS-GNBP hybrid nanosheets. The hybridization markedly increased ¹O₂ production by the BPNSs through plasmon-enhanced light absorption. The nanocomposite exhibited a higher photothermal conversion efficiency than the BPNSs alone. In vitro and in vivo assays indicated that the BPNS-GNBP hybrid nanocomposite exhibited good tumor inhibition efficacy owing to simultaneous dual-modality phototherapy. In vivo, the nanocomposite suppressed deep-seated tumor growth with minimal adverse effects in mice bearing orthotopic A549 human lung tumors. Taken together, these results demonstrated that our BPNS-GNBP nanocomposite could function as a promising dual-modality phototherapeutic agent for enhanced cancer therapy in future cancer treatments. STATEMENT OF SIGNIFICANCE: In this study, we established a new nanocomposite by assembly of gold nanobipyramids (GNBPs) on black phosphorus nanosheets (BPNSs). Characterization of this nanocomposite showed that BPNS-GNBP enhanced ¹O₂ generation and hyperthermia. BPNS-GNBP exhibited good tumor inhibition efficacy in vivo and in vitro owing to simultaneous dual-modal phototherapy functions. Moreover, BPNS-GNBP suppressed deep-seated tumor growth in vivo and did not show adverse effects in mice bearing orthotopic A549 human lung tumors. Overall, these results showed that BPNS-GNBP may be used as a promising dual-modal phototherapeutic agent for enhanced cancer therapy in future clinical applications.

Visible light driven MoS2/α-NiMoO4 ultra-thin nanoneedle composite for efficient Staphylococcus aureus inactivation

MoS₂/α-NiMoO₄ ultra-thin nanoneedle composite was synthesized by microwave hydrothermal process in one step. The nanocomposite revealed the complete destruction of multidrug resistant Staphylococcus aureus (S. aureus) within 150 min under visible light irradiation. According to electron spin resonance measurement and radical trapping experiment, it has been established that O₂¯ acts as a major active species for bacterial inactivation in visible light. The bacterial inactivation was further proved by membrane deformities in bacterial cell membrane, DNA fragmentation, and protein destruction. TEM- elemental mapping confirms the inactivation of S. aureus by reactive oxygen species (ROS) but not the toxicity of photocatalyst. Transient photocurrent responses, electrochemical impedance spectroscopy, and cyclic voltammetry measurements reveal the efficient separation of electron-hole pairs in the composite photocatalyst. The composite photocatalyst shows greater ROS production, higher degree of DNA fragmentation and protein degradation, detrimental effects on the morphology of the bacterial cell wall, outstanding transient photocurrent responses, reduction of interfacial charge transfer resistance, superb oxidation/reduction potential, strong visible light absorption, and adequate separation of photogenerated electron-hole pairs as compared to host photocatalyst. The photocatalytic inactivation mechanism was explained. So, this promising composite photocatalyst can be applied for inactivation of multidrug resistant bacteria in biological waste water.

Near-Infrared Responsive Dopamine/Melatonin-Derived Nanocomposites Abrogating in Situ Amyloid β Nucleation, Propagation, and Ameliorate Neuronal Functions

Alzheimer's disease (AD) is one of the common causes of dementia and mild cognitive impairments, which is progressively expanding among the elderly population worldwide. A short Amyloid-β (Aβ) peptide generated after amyloidogenic processing of amyloid precursor protein exist as intermolecular β-sheet rich oligomeric, protofibriler, and fibrillar structures and believe to be toxic species which instigate neuronal pathobiology in the brain and deposits as senile plaque. Enormous efforts are being made to develop an effective anti-AD therapy that can target Aβ processing, aggregation, and propagation and provide a synergistic neuroprotective effect. However, a nanodrug prepared from natural origin can confer a multimodal synergistic chemo/photothermal inhibition of Aβ pathobiology is not yet demonstrated. In the present work, we report a dopamine-melatonin nanocomposite (DM-NC), which possesses a synergistic near-infrared (NIR) responsive photothermal and pharmacological modality. The noncovalent interaction-mediated self-assembly of melatonin and dopamine oxidative intermediates leads to the evolution of DM-NCs that can withstand variable pH and peroxide environment. NIR-activated melatonin release and photothermal effect collectively inhibit Aβ nucleation, self-seeding, and propagation and can also disrupt the preformed Aβ fibers examined using in vitro Aβ aggregation and Aβ-misfolding cyclic amplification assays. The DM-NCs display a higher biocompatibility to neuroblastoma cells, suppress the AD-associated generation of intracellular reactive oxygen species, and are devoid of any negative impact on the axonal growth process. In okadaic acid-induced neuroblastoma and ex vivo midbrain slice culture-based AD model, DM-NCs exposure suppresses the intracellular Aβ production, aggregation, and accumulation. Therefore, this nature-derived nanocomposite demonstrates a multimodal NIR-responsive synergistic photothermal and pharmacological modality for effective AD therapy.

Photocatalytic degradation of gemifloxacin antibiotic using Zn-Co-LDH@biochar nanocomposite

The aim of the present study was to investigate the photocatalytic performance of biochar (BC)-incorporated Zn-Co-layered double hydroxide (LDH) nanostructures in gemifloxacin (GMF) degradation as a model pharmaceutical pollutant. The as-prepared Zn-Co-LDH@BC showed high photocatalytic efficiency due to the enhanced separation of photo-generated charge carriers using cobalt hydroxide as well as inhibiting the agglomeration of LDH nanostructures by incorporation of BC. According to the results, 92.7% of GMF was degraded through photocatalysis in the presence of Zn-Co-LDH catalyst. The photocatalytic performance of BC-incorporated Zn-Co-LDH was highly dependent on the solute concentration and photocatalyst dosage. The addition of ethanol caused more inhibiting effect than that of benzoquinone (BQ), indicating the major role of ^•OH in decomposition of GMF compared to the negligible role of O₂^•-. A greater enhancement in the photocatalytic degradation of GMF was obtained when the photoreactor containing Zn-Co-LDH@BC nanostructures was oxygenated. Less than 10% drop in the removal efficiency of GMF was observed within five successive operational runs. The results of chemical oxygen demand (COD) analysis indicated the COD removal efficiency of about 80% within 200 min, indicating the acceptable mineralization of GMF. The reaction pathways were also proposed for the photocatalytic conversion of GMF under UV light irradiation.

Microstructure evolution of sandwich graphite oxide/interlayer-embedded Au nanoparticles induced from γ-rays for carcinoembryonic antigen biosensor

With the capability of inducing small particle sizes of supported metal in graphite oxide (GO), the γ-ray irradiation method applied for preparing graphite oxide-gold (GO-Au) nanocomposites as electrochemical immunosensors has attracted specific attention recently. To study the accurate factors influencing the precise morphology and final performance of the prepared composites in the γ-irradiation system, we proposed a facile method to investigate the evolution of the GO structure, size and dispersion of Au nanoparticles (AuNPs) produced with the addition of isopropyl alcohol to the system. The GO-Au nanocomposites were characterized by Fourier transform infrared spectroscopy, x-ray diffraction spectra, Raman spectra, x-ray photoelectron spectroscopy and high resolution transmission electron microscopy. These nanocomposites with sandwich morphology exhibited an excellent immunosensor performance with a low detection limit of 15.8 pg ml^-1 (S/N = 3) and a wide linear range from 1 to 40 ng ml^-1 for detecting carcinoembryonic antigens. The enhanced biosensing performance is attributed to the synergistic effect of γ-irradiation and the precise structure of GO, which endows the smaller size and more uniform distribution of AuNPs on the GO as well as the good signal amplification capability. Furthermore, adopting the γ-irradiation method and use of GO as a precursor is propitious for application in large-scale production because of its high-efficiency and high-yielding characteristics.

Hierarchically structured ternary heterojunctions based on Ce3+/ Ce4+ modified Fe3O4 nanoparticles anchored onto graphene oxide sheets as magnetic visible-light-active photocatalysts for decontamination of oxytetracycline

The main prerequisite of an active visible-light-driven photocatalyst is to effectively utilize the visible light to induce electron-hole (e^-/h⁺) pairs of expanded lifetime. To this end, for the first time, the ternary heterojunctions of CeO₂/Fe₃O₄ /Graphene oxide and Ce³⁺/ Fe₃O₄ /Graphene oxide (CeO₂/Fe₃O₄/GO and Fe_2.8Ce_0.2O₄/GO) were prepared via facile ultrasonic-assisted procedures and employed for destruction of oxytetracycline (OTC) under visible light irradiation. The changes in the relative crystal structure, morphology, atomic and surface functional group composition, magnetic, and optic properties of magnetite were uncovered by various techniques. The substantial degradation and mineralization of OTC via visible light/Fe_2.8Ce_0.2O₄/GO system were thoroughly discussed in terms of narrowed band gap energy, the principal function of Ce³⁺/Ce⁴⁺ and Fe²⁺/Fe³⁺ redox pairs and GO platelets, enhanced charge separation and transfer, and enlarged active surface area. Furthermore, the performance of visible light/Fe_2.8Ce_0.2O₄/GO system was evaluated for treating real wastewater and its efficiency was investigated using a number of enhancers and scavengers. Finally, the generated byproducts in the course of photodegradation were determined and the oxidation pathway, photocatalytic kinetics, and plausible mechanism were proposed. The results confirmed that the introduced Ce ions and graphene oxide sheets boost the photo-catalytic efficiency of magnetite for photodegradation of OTC.

Construction of novel Z-scheme Ag/ZnFe2O4/Ag/BiTa1-xVxO4 system with enhanced electron transfer capacity for visible light photocatalytic degradation of sulfanilamide

A novel Z-scheme system, Ag/ZnFe₂O₄/Ag/BiTa_1-xV_xO₄ with enhanced electron transfer capacity was constructed for degrading sulfanilamide (SAM) using solar light. The photocatalytic activity of Ag/ZnFe₂O₄/Ag/BiTa_1-xV_xO₄ was investigated. The effects of the mass ratio (ZnFe₂O₄:BiTaO₄), doped V dose, Ag wt.% content, and irradiation time on the catalytic performance were evaluated. The reasonable mechanism of Ag/ZnFe₂O₄/Ag/BiTa_1-xV_xO₄ solar photocatalytic degradation was also presented. These results reveal Ag/ZnFe₂O₄/Ag/BiTa_1-xV_xO₄ possesses enhanced photocatalytic performance. The loaded Ag as electron mediator increases the electron transfer rate. Particularly, the doped V and the Fe ions from ZnFe₂O₄ form a powerful electron driving force, which enhances the electron transfer capacity. Ag/ZnFe₂O₄/Ag/BiTa_1-xV_xO₄ shows optimal photocatalytic performance at 2.0 wt.% Ag and 0.5% doped V dose (ZnFe₂O₄:BiTaO₄ = 1.0:0.5). Also, Ag/ZnFe₂O₄/Ag/BiTa_1-xV_xO₄ exhibits high stability and repeatability in photocatalytic degradation. Several active species (^•OH, ^•O₂^-, and h⁺) are produced in the Z-scheme photodegradation of SAM. These results on the enhanced photocatalytic activity of Ag/ZnFe₂O₄/Ag/BiTa_1-xV_xO₄ are ascribed to synergistic photocatalytic effects of ZnFe₂O₄ and BiTa_1-xV_xO₄ mediated through Ag and driven by doped V and Fe ions. Therefore, the Z-scheme Ag/ZnFe₂O₄/Ag/BiTa_1-xV_xO₄ photocatalytic technology proves to be promising for the solar photocatalytic treatment of antibiotics under solar light.

Synergistic Photodynamic and Photothermal Antibacterial Nanocomposite Membrane Triggered by Single NIR Light Source

Herein, we developed a nanocomposite membrane with synergistic photodynamic therapy and photothermal therapy antibacterial effects, triggered by a single near-infrared (NIR) light illumination. First, upconversion nanoparticles (UCNPs) with a hierarchical structure (UCNPs@TiO₂) were synthesized, which use NaYF₄:Yb,Tm nanorods as the core and TiO₂ nanoparticles as the outer shell. Then, nanosized graphene oxide (GO), as a photothermal agent, was doped into UCNPs@TiO₂ core-shell nanoparticles to obtain UCNPs@TiO₂@GO. Afterward, the mixture of UCNPs@TiO₂@GO in poly(vinylidene) fluoride (PVDF) was applied for electrospinning to generate the nanocomposite membrane (UTG-PVDF). Generation of reactive oxygen species (ROS) and changes of temperature triggered by NIR action were both investigated to evaluate the photodynamic and photothermal properties. Upon a single NIR light (980 nm) irradiation for 5 min, the nanocomposite membrane could simultaneously generate ROS and moderate temperature rise, triggering synergistic antibacterial effects against both Gram-positive and -negative bacteria, which are hard to be achieved by an individual photodynamic or photothermal nanocomposite membrane. Additionally, the as-prepared membrane can effectively restrain the inflammatory reaction and accelerate wound healing, thus exhibiting great potentials in treating infectious complications in wound healing progress.

Photocatalytic removal of SO2 using natural zeolite modified by TiO2 and polyoxypropylene surfactant

Air pollution due to emission of various hazardous gases such as SO₂ into the atmosphere and its control is an important environmental issue. Application of photocatalysts is considered as a suitable process to control the gaseous pollutants. In this study, the efficiency of clinoptilolite as a natural zeolite (Ze) modified by TiO₂ (Ze-Ti) and a polymeric surfactant polyoxypropylene (Ze-Ti-POP) for removal of SO₂ was investigated. The nanocomposites were characterized by SEM, EDX, and BET analyses. The photocatalytic oxidation experiments of SO₂ by the nanocomposites and natural zeolite were done under UV irradiation with initial SO₂ concentration of 500 ppm in a photoreactor. The effects of different factors including reaction time, catalyst dose, UV irradiation intensity, humidity content, and calcination temperature and dose of TiO₂ were studied. The modification of clinoptilolite by TiO₂ and POP increased considerably the BET specific surface area of the nanocomposites. The results showed that maximum removal efficiencies of SO₂ by Ze-Ti and Ze-Ti-POP under the optimum experimental conditions were 82.1 and 87.4%, respectively. Adsorption kinetics data well fitted with the Langmuir-Hinshelwood model. Moreover, reusing of nanocomposites after three regeneration cycles indicated that application of Ze-Ti and Ze-Ti-POP nanocomposites could be a promising approach for SO₂ removal. Graphical abstract ᅟ.

C60@C3N4 nanocomposites as quencher for signal-off photoelectrochemical aptasensor with Au nanoparticle decorated perylene tetracarboxylic acid as platform

Herein, a novel signal-off photoelectrochemical (PEC) aptasensor was proposed for sensitive detection of thrombin on the basis of C₆₀@C₃N₄ nanocomposites as quencher and Au nanoparticles (depAu) decorated perylene tetracarboxylic acid (PTCA) as sensing platform. Owing to the excellent membrane-forming of PTCA and superior conductivity of depAu, the PTCA between two depAu layers can simply and effectively produce an extremely high initial photocurrent to afford a precondition for sensitive biodetection. Thereafter, the assembly of C₆₀@C₃N₄ nanocomposites on electrode via typical sandwich reaction enabled the generation of a significantly decreased photocurrent. Here, the C₃N₄ with high surface area not only provided massive binding sites for C₆₀ immobilization, but also partly competed with PTCA in light absorption for producing a significantly smaller photocurrent in the presence of electron donor ascorbic acid (AA). Additionally, both the C₃N₄ and C₆₀ have the poor conductivity, which could inhibit the electron transfer to achieve a further decreased photocurrent, effectively improving the sensitivity of proposed biosensor. As a result, the PEC biosensor in a "signal-off" mode showed an extremely low detection limit down to 1.5 fM, providing a sensitive and universal strategy for protein detection.

Novel Photocatalytic Nanocomposite Made of Polymeric Carbon Nitride and Metal Oxide Nanoparticles

Semiconducting polymers are promising materials for photocatalysis, batteries, fuel applications, etc. One of the most useful photocatalysts is polymeric carbon nitride (PCN), which is usually produced during melamine condensation. In this work, a novel method of obtaining a PCN nanocomposite, in which PCN forms an amorphous layer coating on oxide nanoparticles, is presented. Microwave hydrothermal synthesis (MHS) was used to synthesize a homogeneous mixture of nanoparticles consisting of 80 wt.% AlOOH and 20 wt.% of ZrO₂. The nanopowders were mechanically milled with melamine, and the mixture was annealed in the temperature range of 400–600 °C with rapid heating and cooling. The above procedure lowers PCN formation to 400 °C. The following nanocomposite properties were investigated: band gap, specific surface area, particle size, morphology, phase composition, chemical composition, and photocatalytic activity. The specific surface of the PCN nanocomposite was as high as 70 m²/g, and the optical band gap was 3 eV. High photocatalytic activity in phenol degradation was observed. The proposed simple method, as well as the low-cost preparation procedure, permits the exploitation of PCN as a polymer semiconductor photocatalytic material.

Functional Mesoporous Silica Nanocomposites: Biomedical applications and Biosafety

The rise and development of nanotechnology has enabled the creation of a wide number of systems with new and advantageous features to treat cancer. However, in many cases, the lone application of these new nanotherapeutics has proven not to be enough to achieve acceptable therapeutic efficacies. Hence, to avoid these limitations, the scientific community has embarked on the development of single formulations capable of combining functionalities. Among all possible components, silica-either solid or mesoporous-has become of importance as connecting and coating material for these new-generation therapeutic nanodevices. In the present review, the most recent examples of fully inorganic silica-based functional composites are visited, paying particular attention to those with potential biomedical applicability. Additionally, some highlights will be given with respect to their possible biosafety issues based on their chemical composition.

Multifunctional Two-Dimensional Core-Shell MXene@Gold Nanocomposites for Enhanced Photo-Radio Combined Therapy in the Second Biological Window

Multifunctional nanoplatforms with special advantages in the diagnosis and treatment of cancer have been widely explored in nanomedicine. Herein, we synthesize two-dimensional core-shell nanocomposites (Ti₃C₂@Au) via a seed-growth method starting from the titanium carbide (Ti₃C₂) nanosheets, a classical type of MXene nanostructure. After growing gold on the surface of Ti₃C₂ nanosheets, the stability and biocompatibility of the nanocomposites are greatly improved by the thiol modification. Also importantly, the optical absorption in the near-infrared region is enhanced. Utilizing the ability of the high optical absorbance and strong X-ray attenuation, the synthesized Ti₃C₂@Au nanocomposites are used for photoacoustic and computed tomography dual-modal imaging. Importantly, the mild photothermal effect of the Ti₃C₂@Au nanocomposites could improve the tumor oxygenation, which significantly enhances the radiotherapy. No obvious long-term toxicity of the nanocomposites is found at the injected dose. This work highlights the promise of special properties of MXene-based multifunctional nanostructures for cancer theranostics.

Non-linear release dynamics for a CeO2 nanomaterial embedded in a protective wood stain, due to matrix photo-degradation

The release of CeO₂-bearing residues during the weathering of an acrylic stain enriched with CeO₂ nanomaterial designed for wood protection (Nanobyk brand additive) was studied under two different scenarios: (i) a standard 12-weeks weathering protocol in climate chamber, that combined condensation, water spraying and UV-visible irradiation and (ii) an alternative accelerated 2-weeks leaching batch assay relying on the same weathering factors (water and UV), but with a higher intensity of radiation and immersion phases. Similar Ce released amounts were evidenced for both scenarios following two phases: one related to the removal of loosely bound material with a relatively limited release, and the other resulting from the degradation of the stain, where major release occurred. A non-linear evolution of the release with the UV dose was evidenced for the second phase. No stabilization of Ce emissions was reached at the end of the experiments. The two weathering tests led to different estimates of long-term Ce releases, and different degradations of the stain. Finally, the photo-degradations of the nanocomposite, the pure acrylic stains and the Nanobyk additive were compared. The incorporation of Nanobyk into the acrylic matrix significantly modified the response of the acrylic stain to weathering.

pH and Ultrasound Dual-Responsive Polydopamine-Coated Mesoporous Silica Nanoparticles for Controlled Drug Delivery

A pH- and ultrasound dual-responsive drug release pattern was successfully achieved using mesoporous silica nanoparticles (MSNs) coated with polydopamine (PDA). In this paper, the PDA shell on the MSN surface was obtained through oxidative self-polymerization under the alkaline condition. The morphology and structure of this composite nanoparticle were fully characterized by a series of analyses, such as infrared (IR), transmission electron microscopy, and thermogravimetric analysis. Doxorubicin hydrochloride (DOX)-loaded composite nanoparticles were used to study the performances of responsive drug storage/release behavior, and this kind of hybrid material displayed an apparent pH response in DOX releasing under the acidic condition. Beyond that, upon high-intensity focused ultrasound exposure, loaded DOX in composite nanoparticles was successfully triggered to release from pores because of the ultrasonic cavitation effect, and the DOX-releasing pattern could be optimized into a unique pulsatile fashion by switching the on/off status. From the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, it was observed that our blank nanoparticles showed no toxicity to HeLa cells, but DOX-loaded nanoparticles could inhibit the growth of tumor cells. Furthermore, these composite nanoparticles displayed an effective near-IR photothermal conversion capability with a relatively high conversion efficiency (∼37%). These as-desired drug delivery carriers might have a great potential for future cancer treatment that combine the chemotherapy and photothermal therapy.

Biocompatible FeOOH-Carbon quantum dots nanocomposites for gaseous NOx removal under visible light: Improved charge separation and High selectivity

Development of biocompatible photocatalysts with improved charge separation and high selectivity is essential for effective removal of air pollutants. Iron-containing catalysts have attracted extensive attention due to their low-toxicity and high natural abundance. Here, carbon quantum dots (CQDs) modified FeOOH nanocomposites fabricated using a facile hydrothermal route showed enhanced NO removal efficiency (22%) compared to pure FeOOH. Moreover, generation of toxic NO₂ intermediates was significantly inhibited using the nanocomposites, demonstrating high selectivity for final nitrate formation. Photo-electrochemical results showed that both charge separation and transfer efficiency were significantly improved by CQDs addition, and the lifetime of photo-generated carriers was increased eventually. Density functional theory calculations further elucidated that the suppressed recombination of photo-induced electron-hole pairs was due to enhanced electron migration from the FeOOH to CQDs. A NO degradation mechanism was proposed based on detection of the reactive oxygen species using electron paramagnetic spectroscopy. In addition, the nanocomposite showed good biocompatibility and low cytotoxity, ensuring minimal environmental impact for potential application in large-scale.

Shining Light on Chitosan: A Review on the Usage of Chitosan for Photonics and Nanomaterials Research

Chitosan (CS) is a natural polymer derived from chitin that has found its usage both in research and commercial applications due to its unique solubility and chemical and biological attributes. The biocompatibility and biodegradability of CS have helped researchers identify its utility in the delivery of therapeutic agents, tissue engineering, wound healing, and more. Industrial applications include cosmetic and personal care products, wastewater treatment, and corrosion protection, to name a few. Many researchers have published numerous reviews outlining the physical and chemical properties of CS, as well as its use for many of the above-mentioned applications. Recently, the cationic polyelectrolyte nature of CS was found to be advantageous for stabilizing fascinating photonic materials including plasmonic nanoparticles (e.g., gold and silver), semiconductor nanoparticles (e.g., zinc oxide, cadmium sulfide), fluorescent organic dyes (e.g., fluorescein isothiocyanate (FITC)), luminescent transitional and lanthanide complexes (e.g., Au(I) and Ru(II), and Eu(III)). These photonic systems have been extensively investigated for their usage in antimicrobial, wound healing, diagnostics, sensing, and imaging applications. Highlighted in this review are the different works involving some of the above-mentioned molecular-nano systems that are prepared or stabilized using the CS polymer. The advantages and the role of the CS for synthesizing and stabilizing the above-mentioned optically active materials have been illustrated.

Synthesis of graphenized Au/ZnO plasmonic nanocomposites for simultaneous sunlight mediated photo-catalysis and anti-microbial activity

Sunlight mediated photo-degradation and anti-bacterial activity of hetero junctioned plasmonic binary (Au/ZnO, RGO/ZnO) and ternary (RGO/Au/ZnO) nanocomposites (NC) have been reported. Higher photo-charge carrier generation, increased charge separation, improved active sites for catalysis, enhanced LSPR and larger photo-response regions have been achieved. Decoration with Au nanoparticles (ca. 11 ± 3 and 48 ± 5 nm) and RGO of ZnO (3D/1D) microstructures (aspect ratio 15.18) provides ternary NCs an edge over mono/bi component catalysts. The ternary NC have shown improved dye degradation capacity with 100% efficiency (5 μM MB solution) and average adsorption degradation capacity (Q°) of 83.34 mg/g within 30 min of sunlight exposure (900 ± 30 Wm^-2). Elaborated studies by varying reaction parameters like initial dye concentration, contact time, type of NCs and initial loading of NCs reveals pseudo first order degradation kinetics. 100% microbial killing of Gram positive S.aureus strain with 60 μg/ml of NC using sunlight as activator has proven the simultaneous multiple functionality of the NC. Further, facile green one pot hydrothermal synthesis with water as reaction medium, absence of photo-corrosion of NCs, regeneration ability (ca. 90% for 10 μM solution) of NCs, projects a broader potential application of the synthesized NCs and could reduce the continuous requirement of such material, limiting the environmental toxicity.

Preparation and Characterization of Magnetic and Porous Metal-Ceramic Nanocomposites from a Zeolite Precursor and Their Application for DNA Separation

In this work, metal-ceramic nanocomposites were obtained through short (up to 2 h) thermal treatments at relatively moderate temperatures (750–800 °C) under a reducing atmosphere, using Fe-exchanged zeolite A as the precursor. The as-obtained materials were characterized by X-ray powder diffraction analysis, N2 adsorption at –196 °C, and highresolution transmission electron microscopy. The results of these analyses showed that the nanocomposites consisted of a dispersion of metallic Fe nanoparticles within a porous ceramic matrix, mainly based on amorphous silica and alumina. These nanocomposites were magnetically characterized, and their magnetic response was studied. Finally, the obtained metal-ceramic nanocomposite materials were used in the separation of Escherichia coli DNA from a crude cell lysate. The results of the DNA separation experiments showed that the obtained materials could perform this type of separation.

Construction of plasmonic Ag modified phosphorous-doped ultrathin g-C3N4 nanosheets/BiVO4 photocatalyst with enhanced visible-near-infrared response ability for ciprofloxacin degradation

To realize the full utilization of solar energy, the design of highly efficient photocatalyst with improved visible-near-infrared photocatalysis performance has attracted great attentions for environment pollutant removal. In this work, we rationally employed the surface plasmon resonance effect of metallic Ag in the phosphorus doped ultrathin g-C₃N₄ nanosheets (PCNS) and BiVO₄ composites to construct a ternary Ag@PCNS/BiVO₄ photocatalyst. It was applied for the photodegradation of ciprofloxacin (CIP), exhibiting 92.6% removal efficiency under visible light irradiation (λ>420nm) for 10mg/L CIP, and presenting enhanced photocatalytic ability than that of single component or binary nanocomposites under near-infrared light irradiation (λ>760nm). The improved photocatalytic activity of the prepared Ag@PCNS/BiVO₄ nanocomposite can be attributed to the synergistic effect among the PCNS, BiVO₄ and Ag, which not only improves the visible light response ability and hinders the recombination efficiency of the photogenerated electrons and holes, but also retains the strong the redox ability of the photogenerated charges. According to the trapping experiment and ESR measurements results, OH, h⁺ and O₂^- all participated in the photocatalytic degradation process. Considering the SPR effect of metallic Ag and the established local electric field around the interfaces, a dual Z-scheme electrons transfer mechanism was proposed.

Synthesis of Fluorescent Au Nanocrystals-Silica Hybrid Nanocomposite (FLASH) with Enhanced Optical Features for Bioimaging and Photodynamic Activity

Fluorescent Au nanocrystals (AuNCs)-silica hybrid nanocomposite (FLASH) was synthesized by co-condensation of surface-modified AuNCs. Present FLASH nanocomposite exhibited four times the enhanced photoluminescence and photocatalytic activity compared to single nanocrystals. On the basis of these enhanced optical features, we successfully demonstrated in vitro fluorescence bioimaging of introduced FLASH to human cervical cancer cell line (HeLa). Beyond the confirmation of photocatalytic activity from the photodegradation of methylene blue as a model compound, the regional selective photodynamic therapy of HeLa cells under UV irradiation was also presented. Taken together the enhanced optical features and further potential in theranostic applications, we expect that the present FLASH can be a promising tool for nanobiotechnology field.

NiS and MoS2 nanosheet co-modified graphitic C3N4 ternary heterostructure for high efficient visible light photodegradation of antibiotic

The development of efficient solar driven catalytic system for the degradation of antibiotics has become increasingly important in environmental protection and remediation. Non-noble-metal NiS and MoS₂ nanosheet co-modified graphitic C₃N₄ ternary heterostructure has been synthesized via a facile combination of hydrothermal and ultrasound method, and the ternary heterostructure has been utilized for photocatalytic degradation of antibiotic agents. The antibiotics of ciprofloxacin (CIP) and tetracycline hydrochloride (TC) were photodegraded by the hybrid under the visible light. The optimal photodegradation rate of the ternary heterostructure reaches about 96% after 2h irradiation, which is 2.1 times higher than that of pure g-C₃N₄ for TC degradation. The photocatalytic degradation rates of the ternary heterostructure for both CIP and TC obey the pseudo-first-order kinetic model. The enhanced visible light adsorption and charge separation efficiency contribute to the photocatalytic performance of the ternary heterostructure. This work provides new insights and pathways by which efficient degradation of antibiotics can be achieved and will stimulate further studies in this important field.

TiO2-SnS2 nanocomposites: solar-active photocatalytic materials for water treatment

The study is aimed at evaluating TiO₂-SnS₂ composites as effective solar-active photocatalysts for water treatment. Two strategies for the preparation of TiO₂-SnS₂ composites were examined: (i) in-situ chemical synthesis followed by immobilization on glass plates and (ii) binding of two components (TiO₂ and SnS₂) within the immobilization step. The as-prepared TiO₂-SnS₂ composites and their sole components (TiO₂ or SnS₂) were inspected for composition, crystallinity, and morphology using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX) analyses. Diffuse reflectance spectroscopy (DRS) was used to determine band gaps of immobilized TiO₂-SnS₂ and to establish the changes in comparison to respective sole components. The activity of immobilized TiO₂-SnS₂ composites was tested for the removal of diclofenac (DCF) in aqueous solution under simulated solar irradiation and compared with that of single component photocatalysts. In situ chemical synthesis yielded materials of high crystallinity, while their morphology and composition strongly depended on synthesis conditions applied. TiO₂-SnS₂ composites exhibited higher activity toward DCF removal and conversion in comparison to their sole components at acidic pH, while only in situ synthesized TiO₂-SnS₂ composites showed higher activity at neutral pH.

Development of a novel resin-based dental material with dual biocidal modes and sustained release of Ag+ ions based on photocurable core-shell AgBr/cationic polymer nanocomposites

Research on the incorporation of cutting-edge nano-antibacterial agent for designing dental materials with potent and long-lasting antibacterial property is demanding and provoking work. In this study, a novel resin-based dental material containing photocurable core-shell AgBr/cationic polymer nanocomposite (AgBr/BHPVP) was designed and developed. The shell of polymerizable cationic polymer not only provided non-releasing antibacterial capability for dental resins, but also had the potential to polymerize with other methacrylate monomers and prevented nanoparticles from aggregating in the resin matrix. As a result, incorporation of AgBr/BHPVP nanocomposites did not adversely affect the flexural strength and modulus but greatly increased the Vicker's hardness of resin disks. By continuing to release Ag⁺ ions without the impact of anaerobic environment, resins containing AgBr/BHPVP nanoparticles are particularly suitable to combat anaerobic cariogenic bacteria. By reason of the combined bactericidal effect of the contact-killing cationic polymers and the releasing-killing Ag⁺ ions, AgBr/BHPVP-containing resin disks had potent bactericidal activity against S. mutans. The long-lasting antibacterial activity was also achieved through the sustained release of Ag⁺ ions due to the core-shell structure of the nanocomposites. The results of macrophage cytotoxicity showed that the cell viability of dental resins loading less than 1.0 wt% AgBr/BHPVP was close to that of neat resins. The AgBr/BHPVP-containing dental resin with dual bactericidal capability and long term antimicrobial effect is a promising material aimed at preventing second caries and prolonging the longevity of resin composite restorations.