Multifunctional ZnO/TiO2 nanoarray composite coating with antibacterial activity,cytocompatibility and piezoelectricity

Metal oxides with nanostructures such as zinc oxide (ZnO), titanium dioxide (TiO₂) have been used in biomedical fields for their multifunctional properties. In this study, ZnO/TiO₂ nanoarray (nZnO/TiO₂) coatings were prepared via hydrothermal synthesis followed by low temperature liquid phase method. The particle size of the composites were no more than 100 nm in diameter, assembled into nanoarray on the Ti substrate. In vitro antibacterial experiments showed that the maximum bacteriostatic rate could reach 99% against Staphylococcus aureus and 90% against Escherichia coli, respectively. Moreover, the nZnO/TiO₂ coatings were of cytocompatibility and biocompatibility, promoting the proliferation of MC3T3-E1 and the expression of alkaline phosphatase (ALP). The piezoelectric properties of nZnO/TiO₂ coatings were preliminarily investigated. The smaller the size of the composite particle was, the better the antibacterial property, biocompatibility and piezoelectric properties were. Under the stimulation of the periodic loading, the growth of MC3T3-E1 was promoted, so the secretion of ALP was. The nZnO/TiO₂ composite coating with antibacterial activity, osteogenesis and intellectual stimulation would be a promising smart coating for orthopedic implants.     

Biocompatibility,corrosion resistance and antibacterial activity of TiO2/CuO coating on titanium

In this work, TiO₂/CuO coating was prepared on titanium (Ti) by combination of magnetron sputtering and annealing treatment. The microstructure, biocompatibility, corrosion resistance and antibacterial property of TiO₂/CuO coating were investigated in comparison with pure Ti and TiO₂ coating. The results show that TiO₂/CuO coating is mainly composed of TiO₂ and CuO. In vitro cytocompatibility evaluation suggests that no obvious toxicity appears on the TiO₂/CuO coating, and the coating stimulates the osteoblast spreading and proliferation. Compared with Ti and TiO₂ coating, TiO₂/CuO coating exhibits improved corrosion resistance and antibacterial ability against S.aureus. This study is the first attempt to apply the combination of magnetron sputtering and annealing treatment to introduce the Cu into TiO₂ coating for surface modification of Ti-based implant materials, which may provide a research foundation for further development of bioactive multifunctional coatings to meet the better clinical demand.     

Polyetheretherketone/Nano-Ag-TiO2 composite with mechanical properties and antibacterial activity

Polyetheretherketone (PEEK) is of interest because of its excellent biocompatibility. However, the lack of antimicrobial activity of PEEK limits its use in clinical applications. Silver-loaded nano titanium dioxide (Nano-Ag-TiO₂)/PEEK composites with different mass fractions (1, 2, 3, and 4 wt%) were prepared by hot compression molding to achieve better mechanical and antimicrobial properties. The results of scanning electron microscopy (SEM) and energy dispersive spectrum (EDS) showed that Nano-Ag-TiO₂ successfully modified PEEK. The contact angle of Nano-Ag-TiO₂/PEEK increased compared to PEEK (p < 0.01). The flexural strength, compressive strength, and Vickers hardness of Nano-Ag-TiO₂/PEEK composites first increased and then decreased. When the Nano-Ag-TiO₂ content is 3 wt%, the flexural strength of Nano-Ag-TiO₂/PEEK composite reaches its maximum, which is 171.19 MPa; the compressive strength reaches the maximum, which is 24.7% higher than that of pure PEEK specimens; the Vickers hardness of Nano-Ag-TiO₂/PEEK composite reaches its maximum, which is 19.84% higher than that of pure PEEK specimens. The in vitro antibacterial evaluation reveals that all Nano-Ag-TiO₂/PEEK samples exhibited good resistance and anti-adhesive properties against Staphylococcus aureus (S. aureus). This finding suggests that the 3 wt% Nano-Ag-TiO₂/PEEK composite has better mechanical properties and antimicrobial ability, which is promising for dental applications.     

Improvement for Ti3SiC2/Cu joint brazed using composite fillers with abnormal expansion ceramic particulates

Reducing the residual stresses and improving the mechanical strength of large-scale ceramic/metal brazing joints is an important problem that must be solved for its practical engineering application. Using composite filler with solid-state phase transformation ceramic particulates, it is theoretically feasible to relieve the residual stress and improve the mechanical properties of ceramic/metal brazed joints. In this study, Cu mesh, Ag–28Cu–2Ti (wt.%), and yttria-stabilized zirconia (0.6 mol.% YSZ solid-state phase transformation ceramic particulates) composite power fillers were used in the brazing of Ti₃SiC₂ ceramic and pure copper. The microstructure of joints and YSZ particulates in the interface was investigated and confirmed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), scanning transmission electron microscopy (STEM), and transmission electron microscopy (TEM). In addition, the effect of YSZ particulates content on the mechanical properties of joints was investigated and evaluated by the shear strength. The results show that the interfacial phases were mainly Ti₅Si₃, TiC, Ti_xCu, Ag (s, s), Cu (s, s), and YSZ particulates. Moreover, most of YSZ particulates undergo the solid-state phase transformation from tetragonal zirconia (t-ZrO₂) to monoclinic zirconia (m-ZrO₂) during the cooling process of brazing. The abnormal volume expansion of the solid-state phase transformation reduced the thermal mismatch between Ti₃SiC₂ ceramic and filler, thereby reducing the residual stress in the interface of joint. When using composite filler with 6 wt.% YSZ particulates, the shear strength of Ti₃SiC₂/Cu joint reached the maximum. The maximum average shear strength of the joints was 80.2 MPa, which was about 103.6% more than the joint without YSZ particulates.     

Structural characterization and evaluation of antibacterial and angiogenic potential of gallium-containing melt-derived and gel-derived glasses from CaO-SiO2 system

Gallium-containing glasses were synthesized by the sol-gel and traditional melting techniques to obtain bioactive amorphous materials with antibacterial and angiogenic properties. The influence of gallium ion addition on glass structure was described using two spectroscopic methods (FTIR and ²⁹Si MAS NMR). DSC (Differential Scanning Calorimetry) analysis revealed differences in thermal properties, which were explained by varying ionicity of the chemical bonds. The study shows that gallium ions addition causes a significant difference in glass structure and, as a consequence, in thermal properties, microstructure, and biological response. Dissolution products of the researched glasses incubated in SBF and distillated water were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). To perform the indirect in vitro biocompatibility studies, human osteoblast-like cells (MG-63) were cultivated in the supernatants, which were obtained by incubation of the glass powders in the cell culture medium. The evaluation of the potential angiogenic properties of gallium-doped glasses was performed by measuring the release of human vascular endothelial growth factor (VEGF) from MG-63 cells. Dissolution products of the all samples were tested for antibacterial activity against gram-negative (E. coli) and gram-positive bacteria (S. aureus).     

Construction of g-C3N4/TiO2/Ag composites with enhanced visible-light photocatalytic activity and antibacterial properties

In this study, the multifunctional carbon nitride based composite graphitic-C₃N₄ (g-C₃N₄)/TiO₂/Ag was prepared through a simple and efficient vacuum freeze-drying route. TiO₂ and Ag nanoparticles were demonstrated to decorate onto the surface of g-C₃N₄ sheet. In the ultraviolet–visible absorption test, a narrower band gap and red-shift of light absorption edge were observed for g-C₃N₄/TiO₂/Ag compared to pristine g-C₃N₄ and single-component modified g-C₃N₄/TiO₂. The photodegradation property of g-C₃N₄/TiO₂/Ag was investigated toward the degradation of methylene blue (abbreviated as MB) under the irradiation of visible light. These results indicated that the degradation performance of organic dyes for g-C₃N₄/TiO₂/Ag was obviously improved compared with g-C₃N₄/TiO₂ and g-C₃N₄. The reaction rate constant of MB degradation for g-C₃N₄/TiO₂/Ag was 4.24 times higher than that of pristine g-C₃N₄. In addition, such rationally constructed nanocomposite presented evidently enhanced antibacterial performance against the Gram-negative Escherichia coli. Concentration dependent antibacterial performance was systematically investigated. And 84% bacterial cell viability loss had been observed at 500 μg/mL g-C₃N₄/TiO₂/Ag within 2 h visible light irradiation.     

Self-aggregation and antibacterial activity of N-acylated chitosan

Chitosan was selectively N-acylated with acetic, propionic and hexanoic anhydrides under homogeneous condition to prepare N-acetyl chitosan (NACS), N-propionyl chitosan (NPCS) and N-hexanoyl chitosan (NHCS), respectively. NACSs with different N-acetylation degrees were obtained by controlling the degree of N-acetylation. The chemical structures of N-acylated chitosans including degree of deacetylation (DD), weight-average molecular weight (M_w), radius of gyration (〈S₂〉_Z^1/2) and crystal structure were studied by FTIR, GPC-LLS and X-ray diffraction techniques. Aggregation behavior of N-acylated chitosan was investigated by rheometer. Intramolecular aggregation of NPCS and NACS was stronger with NPCS stronger than NACS. The effect of concentration of polymer, concentration of salt and temperature on self-aggregation of NACS and NPCS was investigated. Hydrophobic interaction of N-acylated chitosan substituted with longer acyl chains was stronger. With moderate DD, intramolecular aggregation occurs predominantly. In vitro antibacterial activity test of N-acylated chitosans was evaluated against two Gram-positive bacteria and two Gram-negative bacteria. Relative inhibition time (RIT) of NHCS with concentration of 1 mg/ml against Escherichia coli and Pseudomonas aeruginosa was more than 2-6 times longer than that of NACS and NPCS. N-acylated chitosan with lower DD had inhibitory effect on the growth of bacteria than that with moderate DD. The results showed that intermolecular aggregation characteristic of N-acetylated chitosans with low DD may help in forming bridge to interact with bacterial cell.     

Fabrication and performance of calcium phosphate cement/small intestinal submucosa composite bionic bone scaffolds with different microstructures

The microstructure of the tissue has a very important determining effect on its performance. Herein, two calcium phosphate cement (CPC)/small intestinal submucosa(SIS) composites bionic bone scaffolds with different microstructures were fabricated by rolling or/ and assembling method. The microstructure, 3D morphology, the crystal phase and mechanical properties of the scaffolds were investigated by micro CT, XRD, FIIR, SEM and electronic universal testing machines respectively. The results showed that the pore size of all scaffolds are in the range of 100–400?µm, which are beneficial to cells growth, migration, and tissue vascularization. Their porosity and the specific surface area were 14.53?±?0.76%, 8.74?±?1.38?m²/m³ and 32?±?0.58%, 26.75?±?2.69?m²/m³ separately. The high porosity and the large specific surface area can provide a larger space and contact area for cells adhesion and proliferation. Meanwhile, compressive strength of the scaffolds soaked were 10?MPa and 27?MPa, about 1.2 folds and 3.2 folds of the original scaffolds, respectively. The results are derived from different microstructures of the scaffolds and chemical bonds between SIS and new phases (hydroxyapatite), and the scaffolds performance steadily increased at near the physiological conditions. Finally, biocompatibility of the scaffolds was evaluated by CCK8, bionic microstructure scaffolds are no cytotoxicity and their biocompatibility is favorable. Based on the microstructure, compressive strength and cytotoxicity of the scaffolds, bionic Harvarsin microstructure CPC/SIS composite scaffold is expected to turn into a scaffold with the excellent properties of real bone.     

Photocatalytic performance and antibacterial mechanism of Cu/Ag-molybdate powder material

Mo-containing semiconductors have attracted significant attention because of their unique photosensitivity, rendering superior visible-light photocatalytic activity. The current study utilizes a combination of theoretical and experimental approaches to systematically investigate the correlation between crystal structure, morphology, photocatalytic activity and stability of rod-shaped copper molybdate (Cu₃Mo₂O₉) and layered silver molybdate nanomaterials (Ag₂MoO₄). At the same time, Escherichia coli (E. coli) is used, as a model gram-negative bacterium, to demonstrate antimicrobial properties of Cu₃Mo₂O₉ and Ag₂MoO₄. The results reveal that as-prepared Cu₃Mo₂O₉ and Ag₂MoO₄ exhibit superior antibacterial performance and excellent photocatalytic activity. Finally, the antibacterial mechanism is proposed based on experimental results, revealing that the sterilization is achieved by ion sterilization and formation of a certain amount of ROS and medium acidification. The present work enhances our understanding of the Cu/Ag-molybdate antibacterial mechanism and demonstrates the feasibility of constructing Mo-containing photocatalysts with high photocatalytic and antimicrobial activities.     

Synthesis and strengthened microwave absorption properties of three-dimensional porous Fe3O4/graphene composite foam

The three-dimensional porous Fe₃O₄/graphene composite foam as a new kind of absorbing composite with electrical loss and magnetic loss was successfully synthesized by a facile method. Fe₃O₄ was evenly attached on structure of graphene sheets which overlapped with each other to form three-dimensional porous graphene foam. The results revealed that when the mass ratio of graphene oxide (GO) and Fe₃O₄ was 1:1, the Fe₃O₄/graphene composite foam possessed the best absorption properties: the minimum reflection loss was up to ??45.08?dB when the thickness was 2.5?mm and the bandwidth below ??10?dB was 6.7?GHz when the content of the composite foam absorbents was just 8%. The micron-sized three-dimensional porous structure provided more propagation paths, enhancing the energy conversion of incident electromagnetic waves. The addition of Fe₃O₄ contributed to improving the impedance matching performance and magnetic loss. The three-dimensional porous Fe₃O₄/graphene composite foam was a kind of high-efficiency wave absorber, providing a new idea for the development of microwave absorbing materials.     

Preparation and characterization of SiO2/polydopamine/Ag nanocomposites with long-term antibacterial activity

Silver nanoparticles (Ag NPs) with diameter of approximately 10 nm were prepared by the reduction of silver nitrate using green synthesis, an eco-friendly approach. The synthesized Ag NPs were homogeneously deposited on silicon dioxide (SiO₂) particles modified with dopamine, leading to the formation of SiO₂/polydopamine (PD)/Ag nanocomposites (NCs) with a core–shell–satellite structure investigated by transmission electron microscopy. The Ag content of SiO₂/PD/Ag NCs determined by inductively coupled plasma optical emission spectrometry was approximately 5.92 wt%. The antibacterial properties of both Ag NPs and SiO₂/PD/Ag NCs against Vibrio natriegens (V. natriegens) and Erythrobacter pelagi sp. nov. (E. pelagi) were investigated by bacterial growth curves and inhibition zone. Compared to Ag NPs, the SiO₂/PD/Ag NCs exhibited superior long-term antibacterial activity, attributed to its controlled release of Ag⁺ ions.     

Optimized synthesis of novel hydroxyapatite/CuO/TiO2 nanocomposite with high antibacterial activity against oral pathogen Streptococcus mutans

The main issue of using hydroxyapatite (HA) in dentistry is accumulation of microorganisms on it that causes tooth decay. The use of nanoparticles can decrease the accumulation of microorganisms, including Streptococcus mutans on HA, and increase its antibacterial effect. The present study aimed to determine the optimal conditions to synthesize HA/CuO/TiO₂ nanocomposites with the highest antibacterial properties. Utilizing the Taguchi method, nine experiments were designed to fabricate nanocomposites using 3 factors of hydroxyapatite, CuO and TiO₂ nanoparticles. The antibacterial activity of the synthesized nanocomposites was evaluated by the colony forming units (CFU) method against S. mutans. Nanocomposite synthesized under experimental conditions 2 (hydroxyapatite 20 mg/ml, CuO 1.50 mg/ml and TiO₂ 1.60 mg/ml) had the highest effect on reducing the growth of S. mutans (1.24 CFU/ml). The results demonstrated the improvement of structural properties, antibacterial activity, and thermal stability by formation of nanocomposite. Owing to the desirable antibacterial properties of the HA/CuO/TiO₂ nanocomposite, it can be used to improve performance in various dental fields.     

Preparation and characterization of a novel antibacterial acrylate polymer composite modified with capsaicin

A novel antibacterial acrylate polymer composite modified with capsaicin was successfully synthesized by a two-step reaction. Capsaicin and acryloyl chloride were firstly esterified, and then applied to solution polymerization with acrylate monomers and styrene. The yield of the esterified products was about 85.3%. The polymer was characterized by Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), thermogravimetric analysis (TGA), contact angle (CA) and antibacterial ring tests. The number-average molecular weight (M_n) of the polymer was 27214, based on the capsaicin-acrylate dosage of 6.5 wt%. The TGA revealed a stable thermal property. The contact angles of the polymers films on tinplate increased from 77.5° to 86.2° with the increasing amount of capsaicin-acrylate. The antibacterial tests demonstrated excellent antimicrobial capability of the polymers.     

A novel biomedical TiN-embedded TiO2 nanotubes composite coating with remarkable mechanical properties,corrosion, tribocorrosion resistance,and antibacterial activity

Tribocorrosion is a severe problem in dental implants, artificial joints, and other implants, and it will affect the long-term safety of the implants. To improve the deficiencies of titanium alloys, we combined physical vapor deposition technology and anodic oxidation to prepare TiN to embed TiO₂ nanotube composite coatings (NTNTs-TiN). Results show that the hardness of the NTNTs-TiN composite coatings reaches 33.2 ± 0.6 GPa, and the grains of the composite coatings were further refined. The NTNTs-TiN coating has the smallest average coefficient of friction (0.22) during tribocorrosion. The tribocorrosion resistance of NTNTs-TiN coating in SBF is increased by ∼44 and ∼2 times compared with Ti6Al4V alloy and TiN coating, respectively. The capillarity effect of the lower contact angle of NTNTs-TiN can form a continuous water-lubrication film at the interface between the counter-ball and coating and produce a lubrication film composed of Ca, Mg, and P, which reduces the coefficient of friction significantly. The NTNTs/TiN composite coating exhibits the best synergistic effect of wear and corrosion. In addition, the NTNTs-TiN coating also exhibits excellent antimicrobial and corrosion properties, which provides a new solution for the long-term safe use of implants in the human body.     

Preparation and antibacterial activity of Ag/TiO2-functionalized ceramic tiles

An Ag/TiO₂ coating was deposited onto glazed ceramic tiles by a sol-gel and spraying method at high temperatures. The coating was characterized by X-ray diffraction, scanning electron microscopy, and atomic force microscopy. The results showed that silver was present in rutile-TiO₂, and the temperature did not change the phase composition of the samples. The Ag/TiO₂ coating had a higher roughness than the TiO₂ coating. The tape test (D 3359–08) showed that the coatings prepared at 950 °C and 1000 °C had good adhesion to the ceramic tile substrate. The antibacterial activity of the coating was tested by photocatalytic sterilization experiments. The results showed that the Ag/TiO₂ coating had a higher antibacterial activity than the TiO₂ coating, and the sterilization efficiency of Escherichia coli, Staphylococcus aureus, Shigella, and Salmonella exceeded 99.655% under 2 h of visible light irradiation. This research provides a method to create Ag/TiO₂ coatings with good thermal resistance, adhesion, and antibacterial activity. This improves the low photocatalytic activity caused by the anatase-to-rutile transformation of TiO₂ at high temperatures and the poor adhesion at low temperatures.     

Mechanical properties and biocompatibility of MgO / Ca3(PO4)2 composite ceramic scaffold with high MgO content based on digital light processing

Magnesium oxide-calcium phosphate (MgO/Ca3(PO4)2) composite ceramic materials are considered a promising class of bioactive materials, expected to be used in artificial bone scaffolds. However, there are few pieces of research on the content of magnesium oxide in composite ceramic scaffolds. To study the effect of magnesium oxide content on the biocompatibility and mechanical properties of magnesium oxide-calcium phosphate composite ceramic scaffolds, six groups of scaffolds with magnesium oxide content of 10 wt%, 20 wt%, 30 wt%, 40 wt%, 100 wt%, and 0 wt% were produced by digital light processing (DLP) printing technology. And scaffolds’ pores size and porosity percentage were 0.6–1 mm and 50%, respectively. The compressive strength of the scaffold increased with the magnesium oxide proportion, and the 40 wt% group was almost twice that of the 0 wt% magnesium oxide group. The 40 wt% and 0 wt% magnesium oxide groups performed better for biocompatibility. Comprehensive analysis of the biocompatibility and mechanical properties of the scaffold confirmed that the 40 wt% magnesium oxide group was the best. The results show that high magnesium oxide content enhanced the mechanical properties and achieved well biocompatibility of the composite scaffolds, broadening the scope of future experimental research.     

Moisture retention and antibacterial activity of modified chitosan by hydrogen peroxide

A series of chitosans with various molecular weights from 1.2 × 10³ to 30.0 × 10⁴ were prepared by oxidative degradation with H₂O₂ and characterized by IR, ¹³C‐NMR, and gel permeation chromatography. Their carboxylic contents increased with a decrease in molecular weight (M_w). The moisture‐absorption and moisture‐retention capacities of resulting chitosans were dependent on both the molecular weight and the degree of deacetylation (DD). Microcalorimetry was first used to study the kinetics of action of the chitosans on a strain of Staphylococcus aureus at pH 7. The antibacterial activity of the water‐soluble chitosan against S. aureus, Escherichia coli, and Salmonella typhi was evaluated by the conventional agar plate method at pH 7. The water‐soluble product with M_w of 0.45 × 10⁴ from initial chitosan of DD of 90% showed high moisture‐absorption and moisture‐retention capacities, and <2% concentration can completely inhibit the growth of these bacteria. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1724–1730, 2002     

Synthesis of large-scale uniform mulberry-like ZnO particles with microwave hydrothermal method and its antibacterial property

Large-scale uniform mulberry-like ZnO particles were successfully synthesized via a fast and simple microwave hydrothermal method. The formation mechanism of mulberry-like ZnO particles was investigated by adding different types of alkalis and different amounts of triethanolamine (TEA). Transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to observe the morphology and crystal structure of the obtained ZnO. The results revealed that the as-prepared ZnO products had an average diameter of about 150 nm and polycrystalline wurtzite structure. The existence of TEA was vital for the formation of nanoparticle-assembled mulberry-like ZnO particles. These mulberry-like ZnO particles exhibited stronger antibacterial effects on Candida albicans than did sheet-like and flower-like ZnO.     

Antimicrobial activity,effects on Streptococcus mutans biofilm and interfacial bonding of adhesive systems with and without antibacterial agent

ObjectivesThis study evaluated the antimicrobial activity (by agar disk diffusion test, AD), viability of S. mutans biofilm (VB), and effect on resin-dentin interface (RDI) of six adhesive systems.MethodsThree adhesives containing antibacterial components (Gluma 2Bond (G2B)/glutaraldehyde, Clearfil SE Protect (CSP)/MDPB and Peak Universal Bond (PUB)/chlorhexidine) and the corresponding adhesives with similar composition, but without antibacterial agents (Gluma Comfort Bond, GCB; Clearfil SE Bond, CSB and Peak LC Bond, PLB) were evaluated. AD was determined measuring the extent of halo formation following application of adhesives and control groups (light cured or not) to cultures of four strict anaerobic and four facultative bacteria. For VB, a UA159 biofilm was grown on adhesive-coated hydroxyapatite discs for five days, collected and processed to count the number of viable cells. For RDI analysis, adhesives were applied according to manufacturers' recommendations and teeth were restored with resin composite, sectioned to obtain bonded slices and visualized by SEM.ResultsAn inhibition halo was observed for G2B (strict anaerobic/light cured and not light cured), CSP (strict anaerobic and facultative/light cured and not light cured) and PUB (strict anaerobic and facultative/not light cured). PUB when light cured produced an inhibition halo on L. casei and S. mutans only. G2B and CSP significantly reduced the viability of S. mutans. Adhesives containing antimicrobial compounds had no detectable effect on RDI.ConclusionThe MDPB-containing bonding agent showed better results of inhibition for all oral pathogens tested and a decrease of viability of Streptococcus mutans biofilm, among the adhesives tested.     

Design of NiS/CNTs nanocomposites for visible light driven catalysis and antibacterial activity studies

The outstanding photocatalytic activity of metal sulphide based photocatalysts have much attention in environmental remediation due to utilization of wide spectrum range. In present paper, the photocatalytic activity of NiS and NiS-CNTs (carbon nanotubes) nanocomposite has been investigated. The hydrothermal technique was used for synthesis of NiS and NiS/CNTs nanocomposite. Structural elucidation of NiS and NiS/CNTs nanocomposite was conducted by X-ray diffraction (XRD) and Fourier transform infra-red (FTIR) techniques. These characterization techniques verified the formation and purity of samples as extra peaks of impurities were not observed in the obtained data. Scherer formula was used to examine the crystallite size of NiS NPs and NiS/CNTs reported that 9.5 nm and 10.2 nm are sizes of NiS and NiS/CNTs respectively. Scanning electron microscopic (SEM) analysis revealed the reduction in the aggregation of NiS and improved the surface area to assist the redox reactions due to presence of CNTs. Current-voltage (I–V) measurements studied the electrical behaviour of photocatalysts. Optical measurements of synthesized samples were analysed by UV–Visible spectrophotometry. The improvement in bandgap energy of nanocomposite was main reason of excellent photocatalytic activity. About 96% degradation of methylene blue was recorded via NiS/CNTs nanocomposite within 50 min. Photocatalytic performance of nanocomposite is faster than individual metal sulphide due to production of more free radicals, Ni–S–C bond development, surface defects and availability of more reaction sites. These features improved the photocatalytic activity of NiS/CNTs and provide an evidence to use carbon nanotubes for the formation of metal sulphide nanocomposites. Antibacterial property of sample was investigated by four Gram negative bacteria (Proteus vulgaris, Klebsiella pneumonia, Escherichia coli and Pseudomonas aeruginosa) and one Gram positive bacteria (Staphylococcus aureus) at different concentrations using disc diffusion method. The possible mechanism for degradation of Methylene blue under UV–Visible illuminations has been discussed. The upgraded degradation of methylene blue by NiS/CNTs nanocomposite supported that it is promising material for treatment of wastewater.