Nanoparticle Hybrid Materials Research Articles

Advanced hybrid nanomaterials based on carboxymethyl-modified biopolymer: Green synthesis and application in sustainable antimicrobial products

The utilization of agricultural by-products for the synthesis of hybrid nanomaterials represents an environmentally sustainable approach. This research aims to comprehensively investigate high-performance silver and copper nanoparticles hybrid materials based on carboxymethyl-modified cellulose / lignin derived from rice husks (CMC / CML-AgNPs and CMC / CML-CuONPs) and apply them for antimicrobial activities. CMC / CML was used to reduce Ag / Cu cations to the atomic level and then efficiently stabilize Ag / CuO nanoparticles, an eco-friendly method and sustainable development. The hybrid nanomaterials were successfully synthesized with spherical shapes and particle sizes ranging from 4 to 16 nm. The diffraction peaks at 38.46°, 46.57°, 64.93°, and 77.55° were ascribed to the face-centered cubic crystal lattice (111), (200), (220), and (311) of silver nanoparticles in the CMC / CML-AgNPs. The peaks were 32.26°, 46.06°, 52.16°, 61.71°, 63.80°, and 71.23° associating with the (110,20−2), (112), (11−3), (310), and (221) plane orientations of CuO nanoparticles. The proposed materials demonstrated highly efficient antimicrobial performances. Particularly, CMC-AgNPs and CML-CuONPs exhibited an inhibitory capability of up to 100 % against E. coli and S. aureus within 72 h. Simultaneously, the antifungal results showed that hybrid nanomaterials have a better ability to inhibit the A. niger than A. flavus fungus. When experimenting on peanut seeds, hybrid nanomaterials showed an inhibitory capability of up to 99.0 % against A. niger. IC50 values of the hybrid nanomaterials range from 0.872 mg/mL to 1.188 mg/mL, confirming that these materials are non-cytotoxic. These materials exhibit significant stability and enduring antimicrobial efficacy, making them ideal for sustainable development of various antibacterial and antifungal blocks for the near future.

Synthesis of cellulose-copper nanoparticle (cCMF/CuNPs) hybrid material for photodegradation of Congo red dye

Synthesis of cellulose-copper nanoparticle (cCMF/CuNPs) hybrid material for photodegradation of Congo red dye

Development of Flexible Medical Electrodes Using Carrageenan-Based Bioplastics with the Addition of Conductive Hybrid Materials Graphite and Silver Nanoparticles.

Electrodes are crucial in medical devices, specifically health monitoring devices for biopotential measurements such as electrocardiography, electromyography (EMG), and electroencephalography. The commonly used rigid electrodes have limitations in their skin-electrode contact quality since they cannot conform to the skin's surface area and body contours. Flexible electrodes have been developed to better conform to the body's surface contours, improving ion transfer and minimizing motion artifacts, thereby enhancing the signal-to-noise ratio (SNR). Bioplastic substrates based on carrageenan have been chosen for their safety, abundance, flexibility, and ease of customization. Hybrid materials of graphite and silver nanoparticles (graphite-AgNPs) exhibit high electron capacitance, low charge transfer resistance, and superior surface catalytic activity. These make them ideal as conductive fillers for bioplastics to achieve good electrical characteristics as electrodes. The effect of the graphite-AgNP filler concentration, graphite particle size, and flexible electrode thickness was evaluated to assess their impact on the electrical and mechanical properties of the fabricated flexible electrodes. The graphite-AgNP fillers were incorporated into a bioplastic matrix, resulting in flexible electrodes with improved conductivity with increasing percentages of graphite-AgNP at the expense of flexibility. The thickness of the flexible electrode was varied to evaluate its effect on the conductivity. A graphite size reduction was performed to improve the electrical properties while maintaining the mechanical properties. The most optimal variation of flexible electrodes with desirable electrical and mechanical properties was achieved by adding 25% graphite-AgNP to the carrageenan, using graphite particles of 400-700 nm, and using the thinnest electrode. The optimized electrode also exhibited an improved SNR value in EMG signal measurements compared to conventional Ag/AgCl electrodes. This research presents a novel approach to developing environmentally friendly, customizable, and flexible electrodes for medical applications.

Sulfur-Rich Polyimide/TiO2 Hybrid Materials with a Tunable Refractive Index.

High refractive index (RI) polyimide/titania nanoparticle hybrid materials were synthesized and characterized in this study. The polyimide synthesis took place via the conventional polycondensation process following the preparation of poly(amic acid), and the nanoparticles were incorporated using an in situ sol-gel process. Thin films of the polyimide/titania nanoparticle hybrids were prepared by optimizing the coating conditions using a spin coater. Thermal imidization of the nanoparticle containing poly(amic acid) films on Si wafers was completed in a temperature-controlled drying oven under a N2 atmosphere. Fourier transform infrared spectroscopy revealed the successful formation of inorganic bonds as well as imide linkages, and transmission electron microscopy results show well-dispersed nanocrystalline TiO2 nanoparticles of around 5 nm in the polymer matrix. Thorough optimization of the reaction time and concentration of TiO2 precursors enabled to achieve a titania content as high as 30% (wt). The RI of the resultant hybrid materials was found to be tunable according to the titania content, while the RI increased linearly with increasing titania content. A homogeneous hybrid material with a very high RI of 1.84 at 589 nm was achieved in this work for 30% (wt) TiO2.

Water-assisted strong underwater adhesion via interfacial water removal and self-adaptive gelation.

In nearly all cases of underwater adhesion, water molecules typically act as a destroyer. Thus, removing interfacial water from the substrate surfaces is essential for forming super-strong underwater adhesion. However, current methods mainly rely on physical means to dislodge interfacial water, such as absorption, hydrophobic repulsion, or extrusion, which are inefficient in removing obstinate hydrated water at contact interface, resulting in poor adhesion. Herein, we present a unique means of reversing the role of water to assist in realizing a self-strengthening liquid underwater adhesive (SLU-adhesive) that can effectively remove water at contact interface. This is achieved through multiscale physical-chemical coupling methods across millimeter to molecular levels and self-adaptive strengthening of the cohesion during underwater operations. As a result, strong adhesion over 1,600 kPa (compared to ~100 to 1,000 kPa in current state of the art) can be achieved on various materials, including inorganic metal and organic plastic materials, without preloading in different environments such as pure water, a wide range of pH solutions (pH = 3 to 11), and seawater. Intriguingly, SLU-adhesive/photothermal nanoparticles (carbon nanotubes) hybrid materials can significantly reduce the time required for complete curing from 24 h to 40 min using near-infrared laser radiation due to unique thermal-response of the chemical reaction rate. The excellent adhesion property and self-adaptive adhesion procedure allow SLU-adhesive materials to demonstrate great potential for broad applications in underwater sand stabilization, underwater repair, and even adhesion failure detection as a self-reporting adhesive. This concept of "water helper" has potential to advance underwater adhesion and manufacturing strategies.

Metal-Enhanced Fluorescent Carbon Quantum Dots via One-Pot Solid State Synthesis for Cell Imaging

In this study, a facile one-pot solid-state synthesis method is developed to shed light on the metal-enhanced fluorescence (MEF) effect in carbon quantum dots (CQDs) and gold nanoparticles (AuNPs) hybrid materials. This is one of the few studies on the solid-state synthesis of N-doped CQDs/gold hybrid nanomaterials. We have conducted various sets of experiments to reveal the role of individual reagents during the nucleation and growth of nanoparticles. We have demonstrated that the addition of a small amount of gold salt illustrates a paramount effect (103-fold) in photoluminescence intensity. This effect is ascribed to MEF, which is caused due to interactions between the excited-state fluorophores and the free surface electrons of metal nanoparticles. It is interesting to note that a further increase of gold yields fluorescence quenching due to a large number of formed AuNPs causing fluorescence resonance energy transfer. By adjusting the volume ratio of gold salt and CD precursors, it is possible to obtain the CQDs-AuNPs hybrid with the highest fluorescence, which produces extensive visible light under 460 nm excitation. Synthesized materials have been successfully used for imaging human dermal fibroblasts and A549 lung epithelial cells. The dose-dependent cytotoxicity studies reveal that the hybrid structures do not have cytotoxicity.

Electrospinning synthesis of CuBTC/TiO2/PS composite nanofiber on HEPA filter with self-cleaning property for indoor air purification

In this study, we have developed a cure for indoor air pollution. Herein, we have fabricated CuBTC metal-organic framework MOF combined with TiO2 nanoparticle hybrid material by solvothermal method and obtained it in powder form. The CuBTC/TiO2 hybrid material absorbed toluene higher than TiO2 and CuBTC. CuBTC/TiO2 powder hinders its practical application, however, for the first time, CuBTC/TiO2/PS-based nanofibers were electrospun on a commercial HEPA filter using the electrospinning process in order to examine their air-filtering capabilities. This air filter exhibited 98.6% adsorption efficiency and 129.45 mg g-1 toluene gas adsorption capacity, although pristine HEPA was incapable of absorbing toluene. After the saturated point, a self-cleaning strategy was employed under UV light for regeneration purposes. In addition, the CuBTC/TiO2/PS nanofiber demonstrated superior PM2.5 removal performance, with a 99.82% filtration rate. Compared to a pure HEPA filter, the CuBTC/TiO2/PS-C nanofiber-based HEPA filter has a very high filtration rate and negligible pressure drop when evaluated at various airflow velocities. This study gives significant insight into the design of a self-cleaning nanofiber air filter to protect public health from indoor air pollution and save lives in the near future.

Pristine, carboxylated, and hybrid multi-walled carbon nanotubes exert potent antioxidant activities in in vitro-cell free systems

Multi-walled carbon nanotubes (MWCNTs) are tubular-shaped carbon allotropes, composed of multiple concentric graphene cylinders. The extended systems of conjugated double bonds, that MWCNTs are constituted by, provide them with high electron affinities, enabling them to act as electron donors or acceptors. Consequently, their potential biomedical applications, as synthetic antioxidant agents, are of particular interest. Based on the above, the purpose of the present study was to evaluate the intrinsic antioxidant properties of pristine and carboxylated MWCNTs, as well as of novel hybrid nanocomposites of MWCNTs and inorganic nanoparticles. To this end, after the synthesis and characterization of MWCNTs, their antiradical, reducing, and antigenotoxic properties were assessed in cell-free assays, using a methodological approach that has been recently proposed by our research group. According to our results, most of the tested MWCNTs exhibited strong antioxidant activities. More elaborately, the hybrid material of MWCNTs and ferrous oxide nanoparticles, i.e., CNTs@Fe3O4, showed robust scavenging capacities in all free-radical scavenging assays examined. As regards reducing properties, the pristine MWCNTs, i.e., CNTs-Ref, exhibited the greater electron donating capacity. Finally, in terms of antigenotoxic properties, the hybrid material of MWCNTs and silicon carbide nanoparticles, i.e., CNTs@SiC, exhibited potent ability to inhibit the formation of peroxyl radicals, thus preventing from the oxidative DNA damage. Conclusively, our findings suggest that the MWCNTs of the study could be considered as promising broad-spectrum antioxidants, however, further investigations are required to evaluate their toxicological profile in cell-based and in vivo systems.

Influence of the degree of polymerization and surface curvature on the supramolecular organization of fixated polythiophenes

Hybrid conjugated polymer (CP)/nanoparticle (NP) materials are found to be very promising materials displaying enhanced properties that exceed their individual counterparts. Those promising properties depend a lot on the organization of the CP within the hybrid material. However, not a lot is known about the supramolecular organization of CPs grafted onto NP materials. Previous research by Ceunen et al. has indicated a hampered organization, however, only small molecules grafted onto a single type on NP was studied. Additionally, new insights into the supramolecular organization of conjugated polymers (CPs) by addition of nonsolvent have demonstrated that a key step towards supramolecular organization is the formation of polymer-solvent clusters. This new information could provide a satisfactory explanation for the potentially disrupted supramolecular organization of CPs grafted onto nanoparticle surfaces as fixating the CPs prohibits the formation of these polymer-solvent clusters and thus no supramolecular organizations can be formed. In order to prove this hypothesis, an in-depth investigation concerning the supramolecular organization of grafted CPs is performed this manuscript by changing the size of the CPs and the nature and size (and thus surface curvature) of the NP material. The results indicate a strong inhibition of the supramolecular organization upon fixation of the CP polymer, which is in line with the formulated hypotheses. • Hybrid materials of nanoparticles and conjugated polymers. • Expression of chirality. • Precision synthesis.

Enhancement of polypyrrole nanotubes stability by gold nanoparticles for the construction of flexible solid-state supercapacitors

Flexible solid-state supercapacitors (FSSCs) have becoming of great interest due to the increasing energy demand of the modern world. Many studies are focusing on the development of different materials for supercapacitor electrodes, however, the combination of high specific capacitance, high stability and low cost in a single material is still a challenge. Herein, we report the fabrication of a FSSC based on a hybrid material of polypyrrole nanotubes (PPy-NTs) and gold nanoparticles (AuNPs). The materials were characterized by scanning and transmission electron microscopies and energy dispersive X-ray spectroscopy and they were also electrochemically characterized in aqueous 1 mol L−1 H2SO4 solution. The FSSC was assembled using a poly(vinyl alcohol) and sodium alginate gel electrolyte and the results showed a high specific capacitance, high stability over 2000 galvanostatic charge/discharge cycles (88%) and good electrochemical performance under bending. The results indicate the great potential to use PPy-NTs/AuNPs hybrid material in flexible all-solid-state symmetric devices.

Direct observation of adsorption and desorption of ds-DNA on graphene oxide and graphene oxide-gold nanoparticle hybrid material: A kineto-mechanistic investigation

Graphene oxide (GO) and its functional derivatives have found tremendous application in the development of biosensors for the detection of nucleic acid hybridization. In this work, we have systematically investigated the adsorption mechanism of oligonucleotides on both GO and graphene oxide-gold nanoparticle (GO-AuNP) hybrid surface and also recovered the adsorbed DNA by applying complementary strands by employing ensemble and single-molecule fluorescence methods. A remarkable observation about the adsorption and desorption mechanism of double-stranded DNA (ds-DNA) on graphene oxide (GO) and GO-AuNP surface has been monitored. The efficiency and rate of adsorption are found to be higher for the GO-AuNP hybrid material compared to that of only GO. The results from the single-molecule-FRET (sm-FRET) indicate that the adsorption of the ds-DNA on the GO-AuNP hybrid material takes place by completely unzipping the strands, i.e. the DNA adsorbs as single-stranded DNA. However, no such clear evidence was observed for the GO. The sm-FRET results reveal the DNA hybridization mechanism to happen “in situ”, i.e. hybridization between the probe and target DNA to form a ds-DNA and desorption thereafter from the GO surface takes place simultaneously. These results also demonstrate that the electrostatic interaction between DNA and GO is of little importance to the overall theory of interaction. This investigation improves the fundamental understanding of DNA hybridization dynamics on GO surface opening new windows in the field of biophysics, sensing, and therapeutic application.

Development of anti-microbial polyvinylidene fluoride (PVDF) membrane using bio-based ginger extract-silica nanoparticles (GE-SiNPs) for bovine serum albumin (BSA) filtration

Hybrid material combines organic-inorganic substituents that can impose hydrophilicity and anti-biofouling properties in polymeric membranes. In this study, ginger extract-silica nanoparticles (GE-SiNPs) hybrid materials were synthesized through the sol-gel technique and was applied as a new additive to improve polyvinylidene fluoride (PVDF) membrane properties. Ginger (Zingiber officinale Roscoe) extract (GE) contains phenol derivatives that provide anti-microbial properties; while silica nanoparticles (SiNPs) plays role to increase membrane hydrophilicity and prevent organic fouling. The PVDF/GE-SiNPs membrane was prepared using non-solvent induced phase separation method and was applied to concentrate Bovine Serum Albumin (BSA). The resulted membranes were characterized in terms of morphology, hydrophilicity, tensile strength, porosity, pure water flux, antibacterial property, and its ultrafiltration performance on BSA concentration. The result analysis of fabricated membrane revealed that increasing the loading amount of GE-SiNPs improved membrane hydrophilicity and enlarged membrane porosity. Water permeability was enhanced up to 9.89 from 4.97 LMH. The highest rejection of BSA solution reached of 68.19 %, with the BSA initial concentration of 50 ppm and trans membrane pressure of 1 bar. The flux recovery ratio (FRR) was satistifically reached of 97.92 %. Furthermore, the PVDF/GE-SiNPs also showed antibacterial properties against Escherichia coli and Staphylococcus aureus.

A green and sustainable cellulosic-carbon-shielded Pd–MNP hybrid material for catalysis and energy storage applications

A straightforward and facile synthesis of cellulosic-carbon-shielded palladium–magnetic nanoparticle hybrid material (Pd-MNP@SCB) is presented here. Naturally abundant cellulose was isolated from waste sugarcane bagasse via simple base hydrolysis method and employed. Large surface area and porosity are crucial factors which can enhance the efficiency of a material in catalysis as well as energy storage application and the same was tried to achieve here using the cellulosic-carbon as a support. The prepared hybrid material was initially screened for its catalytic activity in Suzuki–Miyaura cross-coupling followed by its utilization in energy storage application. Pd-MNP@SCB could catalyze the cross-coupling reaction very efficiently with excellent functional group tolerance and good recyclability. The electrochemical performance was explored for Pd-MNP@SCB assembled in a two-electrode cell configuration. The maximum capacitance was found to be 121.74 F/g at a current density of 0.07 A/g with an excellent cycling stability of 97.69% over 3000 cycles.

Photo-tunable epsilon-near-zero behavior in a self-assembled liquid crystal - nanoparticle hybrid material.

Dynamic tuning of electromagnetic response is an important parameter to realize exotic applications of optical metamaterials. Self-assembly achieved via the incorporation of soft materials is an attractive approach to achieve tunable optical properties. Among the soft materials, liquid crystals are highly sought after due to the inherent soft-stimuli responsiveness. This article reports experimental evidence of tunable epsilon-near-zero (ENZ) behavior brought about by an optical field in a self-assembled liquid crystal – nanoparticle system. The material consists of Au nanoparticles capped with a photo-active chiral liquid crystal ligand. In the liquid crystalline state, the system self-assembles into a helical lamellar superstructure, confirmed by polarizing optical microscopy, HRTEM, XRD, and circular dichroism studies. Upon irradiation with UV light, the localized surface plasmon resonance peak of Au red-shifts by ∼10 nm and gets restored with white light illumination. The effective permittivity of the system obtained from ellipsometry indicates ENZ behavior in the visible spectrum with a bandwidth of ∼45 nm which gets enhanced by a factor of 1.6 on UV illumination. Theoretical calculations, carried out using the effective medium approach, support the experimental findings, making the system an efficient ENZ metamaterial in the optical regime.

Graphene oxide-silver nanoparticle hybrid material: an integrated nanosafety study in zebrafish embryos

This work reports an integrated nanosafety study including the synthesis and characterization of the graphene oxide-silver nanoparticle hybrid material (GO-AgNPs) and its nano-ecotoxicity evaluation in the zebrafish embryo model. The influences of natural organic matter (NOM) and a chorion embryo membrane were considered in this study, looking towards more environmentally realistic scenarios and standardized nanotoxicity testing. The nanohybrid was successfully synthesized using the NaBH4 aqueous method, and AgNPs (~ 5.8 nm) were evenly distributed over the GO surface. GO-AgNPs showed a dose-response acute toxicity: the LC50 was 1.5 mg L-1 for chorionated embryos. The removal of chorion, however, increased this toxic effect by 50%. Furthermore, the presence of NOM mitigated mortality, and LC50 for GO-AgNPs changed respectively from 2.3 to 1.2 mg L-1 for chorionated and de-chorionated embryos. Raman spectroscopy confirmed the ingestion of GO by embryos; but without displaying acute toxicity up to 100 mg L-1, indicating that the silver drove toxicity down. Additionally, it was observed that silver nanoparticle dissolution has a minimal effect on these observed toxicity results. Finally, understanding the influence of chorion membranes and NOM is a critical step towards the standardization of testing for zebrafish embryo toxicity in safety assessments and regulatory issues.

Synthesis and Characterization of Graphene-Silver Nanoparticle Hybrid Materials.

Silver nanoparticles (Ag NPs) play important roles in the development of plasmonic applications. Combining these nanoparticles with graphene can yield hybrid materials with enhanced light–matter interaction. Here, we report a simple method for the synthesis of graphene–silver nanoparticle hybrids on highly oriented pyrolytic graphite (HOPG) substrates. We demonstrate by scanning tunneling microscopy and local tunneling spectroscopy measurements the electrostatic n-type doping of graphene by contact with silver. We show by UV-Vis reflectance investigations that the local surface plasmon resonance (LSPR) of Ag NPs partially covered with graphene is preserved for at least three months, i.e., three times longer than the LSPR of bare Ag NPs. The gradual loss of LSPR is due to the spontaneous sulfurization of non-covered Ag NPs, as revealed by scanning electron microscopy and energy-dispersive X-ray spectroscopy. We show that the Ag NPs completely sandwiched between graphene and HOPG do not sulfurize, even after one year.

Aesthetic Silver-Doped Octacalcium Phosphate Powders Exhibiting Both Contact Antibacterial Ability and Low Cytotoxicity.

Since the introduction of biomaterials, infection has been a serious problem in clinical operations. Although several studies have introduced hybrid materials of calcium phosphate and Ag0 nanoparticles (NPs) that exhibit antibacterial activity, released Ag+ ions and Ag0 NPs are highly cytotoxic and the materials require complex fabrication techniques such as laser irradiation. In this study, we introduce a simple one-pot synthesis method based on crystal-engineering techniques to prepare Ag+-substituted octacalcium phosphate (OCP–Ag) powder that simultaneously exhibits antibacterial activity, little change in color, and low cytotoxicity, thereby overcoming the shortcomings of calcium phosphate as a biomaterial. We used AgNO3-containing (NH4)2HPO4 aqueous solutions as reaction solutions in which Ag+ forms soluble complex [Ag(NH3)2]+ ions that are stable at Ag+ concentrations less than ∼30 mmol/L. Hydrolysis of soluble calcium phosphate in this solution led to pure OCP–Ag when the Ag+ concentration was less than ∼30 mmol/L. Crystallographic analysis showed that Ag+ substituted at the P5 PO4-conjugated sites and was uniformly distributed. When the concentration of Ag+ in the reaction solution was varied, the Ag+ content of the OCP–Ag could be controlled. The obtained OCP–Ag exhibited little color change or Ag+ release when immersed in various media; however, it exhibited contact antibacterial ability toward resident oral bacteria. The prepared OCP–Ag showed no substantial cytotoxicity toward undifferentiated and differentiated MC3T3-E1 cells in assays. Notably, when the Ag+ content in OCP–Ag was optimized (Ag: ∼1 at %), it simultaneously exhibited contact antibacterial ability, little color change, and low cytotoxicity.

Heterogeneous electro–Fenton using three–dimension NZVI–BC electrodes for degradation of neonicotinoid wastewater

Neonicotinoids (NEOs), as the most widely used pesticides, pose a serious threat to water ecosystems, especially clothianidin (CLO). However, the degradation behavior of CLO, as a new type of persistent organic pollutant, is rarely studied in wastewater treatment. To bridge this gap, heterogeneous electro-Fenton system using three-dimension electrodes made of biochar-supported zero-valent iron nanoparticle hybrid material (NZVI–BC), abbreviated as 3D–ICE–EF system, is invented and initially applied in CLO wastewater degradation, without the addition of Fenton reagent. NZVI–BC in 3D–ICE–EF system can concentrate CLO on electrodes by excellent adsorption and effectively eliminate it to achieve self-cleaning effect. In addition, the deposition of iron mud (Fe(OH)3) and the circular utilization of Fe in Fenton system is effectively improved by the addition of hydroquinone (HQ) in 3D–ICE–EF system. The pH applicable scope of Fenton system is extended to alkaline condition by the applications of NZVI–BC electrodes. The increase in the acidity of electrolyte is considered the primary reason of the high degradation efficiency of CLO in 3D–ICE–EF system at an initial pH of 9.0. The degradation performance of 3D–ICE–EF system tends to be promoted by the increase of current intensity and air flow rate. Seven plausible mechanisms of CLO degradation were identified in 3D–ICE–EF system. The ecotoxicity evaluation of degradation products indicated that CLO degradation in 3D–ICE–EF system exhibits a remarkable tendency to reduce toxicity levels.

A logic gate for fluoride anion detection based on carbon dots/gold nanoparticles

A selective logic gate sensor for fluoride anion is first fabricated based on carbon dots/gold nanoparticles hybrid material using 3-mercapto-l,2-propanediol (MP) as the bridge. First, 3-aminophenylboronic acid is chosen as the precursor to fabricate boronic acid decorated carbon dots (b-CDs). Then, b-CDs@MP-gold nanoparticles aggregation is formed by taking advantage of MP as a bridge. As for the occurrence of FRET behavior from b-CDs to gold nanoparticles, the fluorescent signal of b-CDs@MP-Au NPs aggregation based sensor quenches remarkably, called as OFF state. However, fluoride anion binds completely with synthesized b-CDs and induces b-CDs to break away from the surface of gold nanoparticles, activating fluorescent signal, named as ON state. As the concentration of fluoride anion increases, the fluorescence signal of the sensor gradually enhances. The fluorescent response for fluoride anion detection is in the linear range from 9 μM to 117 μM with the detection limit of 1.5 μM. Moreover, the b-CDs@MP-Au NPs based sensor is operated as a logic gate at the molecular level. The experimental results indicate that our present approach can be adapted for establishing the chemical logic gate for the fluoride anion. Furthermore, our proposed strategy holds great potential application in environmental monitoring.

Sonochemical synthesis of graphitic carbon nitrides-wrapped bimetal oxide nanoparticles hybrid materials and their electrocatalytic activity for xanthine electro-oxidation.

A novel network-like magnetic nanoparticle was fabricated on a graphitic carbon nitride through a facile sonochemical route at frequency 20kHz and power 70W. To enhance the electrocatalytic activity of the modified materials, the graphitic carbon nitrides (g-C3N4) was prepared from melamine. Monitoring of xanthine concentration level in biological fluids is more important for clinical diagnosis and medical applications. As modified CuFe2O4/g-C3N4 nanocomposite exhibits better electrochemical activity towards the oxidation of xanthine with higher anodic current compared to other modified and unmodified electrode for the detection of xanthine with larger linear range (0.03-695µM) and lower limit of detection (13.2nM). To compare with these methods, the electrochemical techniques may be an alternative high sensitive method due to their simplicity and rapid detection time. In addition, the practical feasibility of the sensor was inspected with biological samples, reveals the acceptable recovery of the sensor in real samples.