Scanning Atomic Force Microscopy Research Articles

Scaling analysis of electrodeposited copper and the influence of a modified polysaccharide on surface roughness

The influence of a commercially available modified polysaccharide (HydroStar®, Chemstar Chemical Products) on the roughness of short-term and small-scale copper electrodeposits was investigated using Atomic Force Microscopy (AFM), linear scan profilometry and scaling analysis. Copper was deposited on a 316 L stainless steel cathode at 40 °C and 300 A m−2 from an electrolyte containing 40 g L−1 Cu2+, 170 g L−1 H2SO4, 1.5 g L−1 Fe3+, 15 mg L−1 Cl− and either 0, 10, 50 or 100 mg L−1 of HydroStar. Copper deposits produced between 15 and 25 min were imaged using AFM and 2D linear scan profilometry was used to gather surface features of copper samples produced in the range of 120 and 240 min. Scaling analysis was applied to quantify the surface characteristics of limiting roughness (δ) and critical length (LC) from which δ/LC was computed and related to the aspect ratio of surface features. All copper deposits showed a general rise in δ and LC with deposition time but the growth rates decreased when HydroStar was included in the electrolyte indicating that the additive lowers the vertical height of surface features as well as their widths. Furthermore, copper deposits were more consistently produced in the presence of HydroStar and, for a given value of limiting roughness, had surface features with wider base than those created in the absence of the additive. The results show that the modified polysaccharide acts to create smooth copper deposits by generating surface features with lower aspect ratios.

Effects of carbon nanoparticle insertion on stress reduction in hydrogenated amorphous carbon films using plasma chemical vapor deposition

Stress reduction in hydrogenated amorphous carbon (a-C:H) films is of considerable interest for improving their performance as protective films. Herein, we reduced the compressive stress of the films by inserting carbon nanoparticles (CNPs) between two a-C:H layers to form an a-C:H/CNP/a-C:H sandwich structure using a system of plasma chemical vapor deposition (CVD). We measured the deposition features of the CNPs via transmission electron microscopy (TEM) and assessed the dependence of the stress on the thickness of the second a-C:H layer as a parameter of surface coverage, Cp. We represented the stress reduction as a function of Cp; mean size of large CNPs, and thickness of the first and second a-C:H layers. In addition, the surface and film morphologies were investigated using atomic force microscopy (AFM) and cross-sectional scanning electron microscopy (SEM). Compared with films without CNPs, those containing CNPs with 8.9 % Cp showed 36 % lower stress when the thickness of the second a-C:H layer was similar to that of the first (154 nm). The deposited CNPs exhibited two size groups, with mean sizes of the small and large CNPs of 5 and 16 nm, respectively. Stress reduction was strongly correlated with the distance between large CNPs. The insertion of CNPs between a-C:H films affects the surface morphology of the second layer, and the stress decreases when the growth stage of the film starts transitioning from three-dimensional (3D) to two-dimensional (2D).

Fluid confinement within a branched polymer structure enhances tribological performance of a poly(2-methacryloyloxyethyl phosphorylcholine)-surface-modified contact lens.

The poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC)-modified, silicone hydrogel, contact lens (CL) material lehfilcon A has previously been demonstrated to have a lubricious, antifouling and ultra-soft surface. This study provides confirmatory identification of the outer polymer structures on this CL surface as branched PMPC structures. It further aims to understand their role in providing enhanced tribological performance via fluid confinement. A combination of scanning transmission electron microscopy and atomic force microscopy infrared spectroscopy has been used to achieve both morphological and chemical confirmation of branched PMPC structures resembling the polysaccharide species present on the surface of the cornea. Measurements of the fluid-confinement behaviour of this layer, by means of nanoindentation experiments, show it to resist squeeze-out of the interstitial fluid, thereby boosting lubrication by virtue of a fluid-load-support mechanism. Tribological testing of CLs showed this effective lubrication to be maintained after one month of daily wearing.

Structural, Morphological, and Optoelectronic Properties of RF Sputtered AZO Thin Films on Glass and Polymer Substrates: A Comparative Study

This paper investigates the thickness-dependent structural, morphological, and optoelectronic properties of Al-doped ZnO (AZO) thin films deposited on glass and flexible polyethylene terephthalate (PET) substrates via confocal magnetron sputtering. The film’s thickness ranged from 50 to 130 nm. X-ray diffraction results show that all AZO films on glass have better structural properties than those on PET. Furthermore, the (002) peak intensity and crystallite size on both substrates improved progressively with thickness. Field emission scanning electron microscopy and atomic force microscopy images revealed that the film morphology and surface roughness are dependent on substrate and thickness. According to the UV–vis-NIR measurement results, the air-referenced transmittance spectra of films on PET were slightly lower than those on glass; however, compared to films on glass, the substrate-referenced transmittance of PET films was higher. Moreover, for both substrates, it is found that the bandgap of fabricated thin films decreases with thickness. Photoluminescence spectra show that for glass and PET substrates, the total luminescence of AZO decreases with increasing film thickness and that green and red emissions are absent from AZO films deposited on PET substrates. AZO films deposited on glass substrates exhibit superior electrical and optoelectronic characteristics.

Na2SO4-assisted shift in the nucleation mechanism of copper-electrocrystallization from an acidic bath

In this study, the effect of sodium sulphate (Na2SO4) on the nucleation mechanism of copper films during electrodeposition was investigated. Voltammetric and chronoamperometric studies were employed to analyze the kinetics of electrochemical nucleation. Phase analysis of the nucleated copper was performed via X-ray diffraction, while morphological and topographical studies were conducted using scanning electron microscopy (SEM) and atomic force microscopy (AFM) to further validate the electrochemical findings. The deposits obtained in the presence of Na2SO4 were finer and more closely packed compared to those formed without Na2SO4. Additionally, the roughness of the deposits varied between the two conditions, with films formed without Na2SO4 being slightly smoother. The results indicate that the addition of Na2SO4 changed the nucleation mechanism from charge transfer controlled to mass transfer controlled.

Mechanism of action of the novel reagent dodecyl trimethyl ammonium chloride on magnesite and quartz surfaces

Silica impurities are one of the key factors that reduce the quality of magnesite. In this experiment, dodecyl trimethylammonium chloride (KDMP) was used as a quartz collector for silica-magnesium separation, and mineral flotation tests demonstrated that KDMP can effectively desiliconize and purify magnesite under the conditions of 20 mg/L and pH 5.0. Contact angle and Zeta potential measurements show that KDMP alters quartz’s characteristics more than magnesite. X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (FTIR) tests show that KDMP works on quartz and adsorbs solely on its surface, not on magnesite. Field Emission Scanning Electron Microscopy (FESEM) and Atomic Force Microscopy (AFM) images revealed that the KDMP collector adsorbed exclusively on the quartz surface, forming a layer of adsorption structure, but was weak on the magnesite surface. As a result, the KDMP collector is a highly intriguing flotation collector that can efficiently separate magnesite from quartz while also introducing a new form of collector for the separation and purification of low-grade magnesite.

Enhancement of dielectric constant in Sm:Zr co-doped HfO2 films synthesized by cost-effective method

Sm, Zr co-doped HfO2 films were deposited on a p-type silicon wafer using a cost-effective spin coating method. The influence of Sm, Zr co-doping concentration variation on structural, compositional, morphological, and electrical properties was examined. The dominance of the orthorhombic phase (o-phase) in comparison to the monoclinic phase was noted to rise with the simultaneous increment of Sm doping concentration and decrement of Zr concentration. A decrease in oxygen vacancies was noted for all the Sm, Zr co-doped HfO2 films from XPS results. Nonporous and uniform distribution of grains was observed from Field Emission Scanning Electron Microscope (FESEM) and Atomic Force Microscopy (AFM) studies. Electrical studies of MOS capacitors based on Sm, Zr co-doped HfO2 films revealed a low leakage current. C-V studies exhibited an increment of dielectric constant and a decrement of interface trap densities. Further, to obtain insights into the microscopic features of Sm, Zr co-doped films, impedance and modulus studies have been performed. The obtained results imply the potential of tuning Sm, Zr co-doping concentrations in HfO2 towards stabilization of the orthorhombic phase and to enhance the dielectric constant of the films.

Randomized Clinical Trial: Bone Bioactive Liquid Improves Implant Stability and Osseointegration

Implant stability can be compromised by factors such as inadequate bone quality and infection, leading to potential implant failure. Ensuring implant stability and longevity is crucial for patient satisfaction and quality of life. In this multicenter, randomized, double-blind clinical trial, we assessed the impact of a bone bioactive liquid (BBL) on the Galaxy TS implant’s performance, stability, and osseointegration. We evaluated the impact stability, osseointegration, and pain levels using initial stability quotient (ISQ) measurements, CBCT scans, and pain assessment post-surgery. Surface analysis was performed using scanning electron microscopy (SEM) and atomic force microscopy (AFM). In vitro studies examined the BBL’s effects on dental pulp pluripotent stem cells’ (DPPSCs’) osteogenesis and inflammation modulation in human macrophages. All implants successfully osseointegrated, as demonstrated by the results of our clinical and histological studies. The BBL-treated implants showed significantly lower pain scores by day 7 (p < 0.00001) and improved stability by day 30 (ISQ > 62.00 ± 0.59, p < 8 × 10−7). By day 60, CBCT scans revealed an increased bone area ratio in BBL-treated implants. AFM images demonstrated the BBL’s softening and wettability effect on implant surfaces. Furthermore, the BBL promoted DPPSCs’ osteogenesis and modulated inflammatory markers in human primary macrophages. This study presents compelling clinical and biological evidence that BBL treatment improves Galaxy TS implant stability, reduces pain, and enhances bone formation, possibly through surface tension modulation and immunomodulatory effects. This advancement holds promise for enhancing patient outcomes and implant longevity.

Surface modification of ilmenite with sodium persulfate and its effect on flotation performance

Ilmenite is a challenging mineral to float, making the improvement of its floatability a prominent research focus. This study proposes a novel surface modification method using sodium persulfate (Na2S2O8) activation in the sodium oleate system for ilmenite. The activation mechanism was investigated using micro-flotation, zeta potential analysis, adsorption measurement, contact angle measurement, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), flotation kinetics calculation, and thermodynamic analysis. Flotation tests demonstrated a significant increase in ilmenite recovery after Na2S2O8 activation under weakly acidic conditions, particularly at pH 4.0, where recovery increased from 12.41 % to 67.24 %. Zeta potential, contact angle, and adsorption tests revealed that Na2S2O8 activation positively shifted the surface potential of ilmenite, enhancing sodium oleate adsorption and increasing hydrophobicity. FT-IR, XPS, and thermodynamic analyses showed that Na2S2O8 facilitated the conversion of Fe2+ to Fe3+ on the ilmenite surface. Additionally, activation with sodium persulfate increased the Fe3+ content on the surface from 20.13 % to 43.50 %, leading to the formation of a more stable ferric iron oleate. AFM scans confirmed that Na2S2O8 activation significantly increased the area and thickness of sodium oleate adsorbed on the ilmenite surface compared to unactivated ilmenite.

Hevea brasiliensis rubber particles' fluid interfaces reveal size impact on early coagulation steps

Natural rubber originates from the coagulation of rubber particles (RP) from Hevea brasiliensis latex. The size distribution of Hevea RP is bimodal with the presence of small rubber particles (SRP) and large rubber particles (LRP). This study aims at getting a better understanding of the early coagulation steps of Hevea RP taking into account the particle size. SRP and LRP were obtained by centrifugation of freshly tapped ammonia-free latex from RRIM600 clone. Size and zeta potential measurements showed that both RP fractions were efficiently separated and stable in basic buffer. SRP and LRP dispersions were placed in a Langmuir trough and RP were let to adsorb at the air-liquid interface to form interfacial films. Surface tension and ellipsometry indicate that the formation kinetics and the stabilization of the film at the air-liquid interface are faster for SRP than LRP. Moreover, the arrangement of RP at the interface differs between SRP and LRP, as shown by Brewster angle microscopy, atomic force microscopy and confocal laser scanning microscopy. First, the RP membrane and cis-1,4-polyisoprene core spread at the air-liquid interface before clustering. Then, while the SRP fuse, the LRP keep their structure in individual particles in floating aggregate. The role of the non-isoprene molecules on the different organization of SRP and LRP films is discussed, the one of the two major RP proteins, SRPP1 (Small Rubber Particle Protein) and Rubber Elongation Factor (REF1) in the early coagulation steps.

Deposition of Nb-doped TiO2 thin films for electrochromic applications with high durability and stability

Although pure TiO2 has no significant electrochromic properties, it is used to investigate the electrochromic properties after the doping process. In this paper, TiO2 thin film was doped with Nb, and its surface and electrochromic properties were subsequently investigated. A thermionic vacuum arc deposition system was used to deposit the doped thin film, which was then annealed. Field emission scanning electron microscopy and atomic force microscopy were employed to obtain the surface morphology of the films. The Ti/Nb ratio was found to be 0.033. After annealing, the transparency value of the thin film increased to 85 %. The coloration efficiency was determined to be 375 cm2/C. The band gap of Nb2O5 was found to be in the range of 3.1–4.0 eV. For TiO2, the band gap was found to be 3.2 eV. Transmittance variation is about 3 %, and band gap variation in colouring and bleaching states is about 0.5 eV. During the colouring and bleaching states, the band gap value of the sample changed from 3.5 eV to 3.0 eV. The specific capacitance is 3 F/g for the thin film. Finally, the results show that Nb-doped TiO2 is a promising candidate for high-performance and long-life electrochromic material.

Multi-view neural 3D reconstruction of micro- and nanostructures with atomic force microscopy

Atomic Force Microscopy (AFM) is a widely employed tool for micro- and nanoscale topographic imaging. However, conventional AFM scanning struggles to reconstruct complex 3D micro- and nanostructures precisely due to limitations such as incomplete sample topography capturing and tip-sample convolution artifacts. Here, we propose a multi-view neural-network-based framework with AFM, named MVN-AFM, which accurately reconstructs surface models of intricate micro- and nanostructures. Unlike previous 3D-AFM approaches, MVN-AFM does not depend on any specially shaped probes or costly modifications to the AFM system. To achieve this, MVN-AFM employs an iterative method to align multi-view data and eliminate AFM artifacts simultaneously. Furthermore, we apply the neural implicit surface reconstruction technique in nanotechnology and achieve improved results. Additional extensive experiments show that MVN-AFM effectively eliminates artifacts present in raw AFM images and reconstructs various micro- and nanostructures, including complex geometrical microstructures printed via two-photon lithography and nanoparticles such as poly(methyl methacrylate) (PMMA) nanospheres and zeolitic imidazolate framework-67 (ZIF-67) nanocrystals. This work presents a cost-effective tool for micro- and nanoscale 3D analysis.

Morphological study of remineralization of the eroded enamel lesions by tyrosine-rich amelogenin peptide

BackgroundTyrosine-rich amelogenin peptide (TRAP) is the main amelogenin digestion product in the developmental enamel matrix. It has been shown to promote remineralization of demineralized enamel in our previous study. However, direct evidence of the effect of TRAP on the morphology and nanostructure of crystal growth on an enamel surface has not been reported. This study aimed to examine the effect of TRAP on the morphology of calcium phosphate crystals grown on early enamel erosion using a pH-cycling model.MethodsEroded lesions were produced in human premolars by 30-second immersion in 37% phosphoric acid. Forty-five samples of eroded human premolar enamel blocks were selected and randomly divided into 3 groups: deionized water (DDW, negative control); 100 µg/mL TRAP, and 2 ppm sodium fluoride (NaF, positive control group). For 14 days, the specimens were exposed to a pH-cycling model. Using scanning electron microscopy (SEM) and atomic force microscopy (AFM) methods, the surface morphology, calcium-phosphorus ratio, and enamel surface roughness were examined. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) were used to assess crystal characteristics.ResultsAfter pH-cycling, compared to the two control groups, the surface of the eroded enamel of the peptide TRAP group shows a large number of new, densely arranged rod-like crystals, parallel to each other, regularly arranged, forming an ordered structure, with crystal morphology similar to that of natural enamel. The crystals are mostly hydroxyapatite (HA).ConclusionThis study demonstrates that the peptide TRAP modulates the formation of hydroxyapatite in eroded enamel and that the newly formed crystals resemble natural enamel crystals and promote the remineralization of enamel, providing a promising biomaterial for remineralization treatment of enamel lesions.

Experimental and DFT analysis of the concentration dependency of corrosion inhibition by a pyridine Schiff base for mild steel in HCl solution

In the present article, we studied the corrosion inhibition of the pyridine Schiff base N, N´-bis(4-dimethylaminobenzaldehyde)-2, 6-pyridinediamine (4-DMBPy) during the corrosion of mild steel AISI 1020 in a 0.1 M HCl solution. The electrochemical analysis by potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) revealed that the Schiff base promotes a protective efficiency up to 81 % at 25 ppm, followed by a decrease at higher concentrations.The Schiff base – surface interactions follow a Freundlich isotherm, indicating a physical adsorption mechanism. The theoretical calculus by Fukui function and dual reactivity descriptors confirmed the physical interaction with mild steel and the low reactivity of the adsorbed species that led to corrosion protection affecting the cathodic and anodic reactions. The quantum calculations by density functional theory (DFT) indicated that protective efficiency decreases due to the tendency to interact with each other. These interactions led to the formation of molecular aggregates and a desorption process. Molecular dynamics (MD) simulations exhibited that the 4-DMBPy molecule preferred to arrange parallel to the Fe (110) surface through physical adsorption. The results were complemented by the scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, and atomic force microscopy (AFM) analyses to reveal the further information about the corrosion process and the effect of the 4-DMBPy Schiff base as a corrosion inhibitor.

Investigation of PVDF‐co‐HPF based ultrafiltration polymer inclusion membrane for the extraction of cadmium ions

AbstractUltrafiltration polymer inclusion membranes (UPIMs) have become increasingly significant for the separation and purification of heavy metals from industrial wastes and wastewater due to their convenience compared to other liquid membranes. A novel process for cadmium separation and recovery has been developed using biodegradable ion carriers, specifically room temperature ionic liquids with various molecular structures. This innovation has greatly enhanced the efficiency and application of UPIMs for cadmium separation, while also providing the membranes with unique functional properties. In this study, various UPIMs were produced using polyvinyl fluoride hexafluoropropylene (PVDF‐co‐HPF) as the base polymer, different plasticizers, and symmetric room temperature ionic liquids as ion carriers. The ability of these membranes to extract cadmium ions was evaluated, demonstrating a removal rate of 9.70 μmol s−1 from a 25 ppm Cd(II) solution under optimum conditions. The selectivity and stability of the optimized UPIM were examined under different conditions to obtain a deeper insight into of its performance. The morphological characteristics of the optimized UPIM were examined using scanning electron microscopy and atomic force microscopy techniques.

Cost-effective production of Titania nanoparticles for the modification of transformer insulating oil

Nanofluids are prospective solutions for improving the transformer dielectric strengthby adding nanoparticles to the standard oils used in transformers.Oil-based titania nanofluids are becoming increasingly popular due to their superior insulating qualities and distinctive thermal performance, and they areconsideredas possible replacements in the domains of transformer insulating oils.This paper describes the industrial synthesis of titania nanoparticles for improving the insulating characteristics of virgin oil used in transformers.The titania nanoparticles were analyzed using an X-ray diffractogram (XRD), which revealed a prominent peak at Bragg angle 25O, indicating that the titania nanoparticles were generated in the anatase phase. Fourier transform infrared (FTIR) spectroscopy study endorsed the formation of Ti-O-Ti, Ti-OH, C-H and O-H stretching vibrations at 760 cm−1, 1345 cm−1, 2475 cm−1, and 3646 cm−1 wavenumbers respectively. Field emission scanning electron microscopy (FESEM) and Atomic Force Microscopy (AFM) examinations on the produced titania nanoparticles revealed that the particles had a circular shape with a diameter of 55 nm and an average roughness value of roughly 3.6 nm respectively.The viscosity of the host virgin oil and the nanoparticles-filled nanofluid were examined, and higher viscosity values were found as particle concentration increased.The effective conductivity study with the zeta potential and thermal conductivity fluctuation with temperature variation also revealed that at higher temperatures, conductivity with the zeta potential increased and thermal conductivity dropped. Furthermore, the breakdown strength of the titania nanoparticles-based virgin oil was observed to be effectively increased with the particle concentration.

Liquid-phase shear exfoliation of graphite and its application as corrosion protection coating on aluminum substrate

Although aluminum (Al) or its alloys are moderately protected by a native oxide layer, the presence of chloride ions in aqueous media in direct contact causes pitting attacks and accelerates corrosion. Using graphene as a coating protector can obstruct corrosion due to its numerous chemical and physical properties. This study investigates corrosion protection of Al using graphene nanosheets (GNSs) produced by liquid phase shear exfoliation method (LPE). To do so, few layer-thick graphene nanosheet colloidal solutions were produced by a scalable eco-friendlier lower cost approach. The GNSs were thoroughly characterized using complementary characterization techniques to determine its quality. Spectroscopic and microscopic analyses indicate the synthesis of few-layers graphene (≤ 5 layers) with a high quality. Once approved, the colloidal solution of GNSs was spread over Al substrate by spray coating method, widely used in industrial manufacturing. Raman and near infrared spectroscopy, X-ray diffraction, microscopy techniques including scanning electron, transmission electron and atomic force microscopies were used to investigate morphological and structural behavior of coated GNSs films either on glass or Al substrates. Density functional theory (DFT) calculations revealed the interaction between the two materials is of the physisorption type, with almost no charge transfer and almost no effect of the number of graphene layers. Electrochemical measurements enabled to investigate the corrosion resistance of GNSs films and its stability over time in a 0.5 M sodium chloride (NaCl) solution, similar to marine surroundings. It was found that introducing a GNSs film can indeed reduce the corrosion rate and preserve Al substrate for an extended period.

Eco-friendly synthesis and characterization of silver nanoparticles from an endemic plant and their antibacterial potency - A sustainable approach

The biomass-assisted fabrication of green nanoparticles is in rise in recent years as it ensures environment compatibility and economically smartness. Now-a-days, the scientific world utilizing the abundantly available plant biomass to synthesize nanoparticles. The present study attempted the biofabrication of silver nanoparticles (Ag NPs) from the silver salt (silver nitrate) using the leaf extract from the plant, Jatropha maheshwarii. The functional groups attached, morphological features and the other qualities of J. maheshwarii mediated Ag NPs was done using the characterization techniques (spectroscopic and micrographic) like Fourier Transform Infra Red spectroscopy (FTIR), X-Ray Diffraction analysis (XRD), Energy Dispersive X-ray Analysis (EDXA), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). These analyses showed that the nanoparticles are spherical and flakes in shape and the XRD results indicated an average particle size of 25.98 ​nm. These nanoparticles were employed as an antibacterial agent on different bacteria such as Staphylococcus aureus, Bacillus thuringiensis, Escherichia coli, Pseudomonas aeruginosa and Salmonella typhi. The significant antibacterial activity exhibited against S. typhi (19 ​mm) at a concentration of 100 ​μg/ml. Furthermore, the mode of action of these bio-synthesized silver nanoparticles as an antibacterial agent was screened by the amount of reducing sugars and proteins leaked from the bacterial cells under study after treating with nanoparticles (leakage assay). These findings encourage the future development of these green nanoparticles as potential antibacterial drugs.

Evaluation of surface roughness, cytotoxicity, and antibacterial effects of silver nanoparticle coating on copper nickel titanium orthodontic arch wires – in vitro study

BACKGROUND: Surface roughness of arch wires directly impacts their corrosion behavior, friction resistance, and plaque accumulation, which may hinder tooth movement and lead to dental caries. OBJECTIVES: The study aims to synthesize vanillin-mediated silver nanoparticles (AgNPs), characterize them, assess surface roughness and cytotoxicity of arch wires after silver nanoparticle coating, and test their antibacterial properties. MATERIALS AND METHODS: Nine copper–nickel–titanium arch wires (CuNiTi) were cut into equal pieces. Three were sent for surface roughness assessment, three for cytotoxicity, and three for antibacterial testing. Dip coating of wires was done using the sol–gel thin film method. The surface roughness (Ra) before and after coating was evaluated using scanning electron microscopy and atomic force microscopy. Cytotoxicity testing was done with a (3- (4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay using gingival fibroblasts. Statistical analysis was done using SPSS software. Antibacterial activity against S. mutans was tested using the Agar-well diffusion method. RESULTS: The CuNiTi wires were coated successfully, and the coating appeared homogeneous. The mean Ra after coating (297.3+/- 30.4 nm) was significantly less than that before coating (339.7+/-49.2 nm). AgNPs showed minimal cytotoxicity against human gingival fibroblasts at different concentrations. Optical microscopy showed over 90% viability between 12.5 and 100 µg/ml. At 100 µg/ml, only 80% of cells remained viable. AgNP coating is biocompatible at concentrations up to 75 µg/ml. There was a significant intergroup difference in the zone of inhibition (antibacterial activity) noted with higher values in noncoated wires. (P value <0.007). CONCLUSION: AgNPs coated on CuNiTi arch wires showed reduced surface roughness and minimal cytotoxic effects on human gingival cells and good antibacterial activity against S. mutans compared to noncoated arch wires.

An unusual impedimetric biosensor design based on 3-MPDS for highly sensitive detection of AFB1 in food samples

Aflatoxin B1 (AFB1), a mycotoxin produced by fungi of the genus Aspergillus, particularly Aspergillus flavus, is recognized as the aflatoxin with the highest carcinogenic and mutagenic potential. This study presents a cost-effective, disposable AFB1 biosensor system based on 3-mercaptopropyltrimethoxysilane (3-MPDS) and the highly sensitive impedance technique. The surfaces of the ITO-PET (indium tin oxide/polyethylene terephthalate) electrodes were modified with 3-MPDS, and N-hydroxysuccinimide (NHS) was used as a crosslinker. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques were employed for immobilization, optimization, and analytical studies. Additionally, the surface morphology of the biosensor was analyzed using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The biosensor demonstrated a linear range from 0.01 fg/mL to 200 fg/mL, with a limit of detection (LOD) of 0.01 fg/mL and a limit of quantification (LOQ) of 0.04 fg/mL. Finally, the proposed biosensor was tested and validated with real food samples, including rice, peanuts, milk, chili pepper, and corn.