Biocompatible Electrochemical Sensor Based on Platinum-Nickel Alloy Nanoparticles for In Situ Monitoring of Hydrogen Sulfide in Breast Cancer Cells.

Hydrogen sulfide (H2S), an endogenous gasotransmitter, is produced in mammalian systems and is closely associated with pathological and physiological functions. Nevertheless, the complete conversion of H2S is still unpredictable owing to the limited number of sensors for accurate and quantitative detection of H2S in biological samples. In this study, we constructed a disposable electrochemical sensor based on PtNi alloy nanoparticles (PtNi NPs) for sensitive and specific in situ monitoring of H2S released by human breast cancer cells. PtNi alloy NPs with an average size of 5.6 nm were prepared by a simple hydrothermal approach. The conversion of different forms of sulfides (e.g., H2S, HS-, and S2-) under various physiological conditions hindered the direct detection of H2S in live cells. PtNi NPs catalyze the electrochemical oxidation of H2S in a neutral phosphate buffer (PB, pH 7.0). The PtNi-based sensing platform demonstrated a linear detection range of 0.013-1031 µM and the limit of detection was 0.004 µM (S/N = 3). Moreover, the PtNi sensor exhibited a sensitivity of 0.323 µA µM-1 cm-2. In addition, the stability, repeatability, reproducibility, and anti-interference ability of the PtNi sensor exhibited satisfactory results. The PtNi sensor was able to successfully quantify H2S in pond water, urine, and saliva samples. Finally, the biocompatible PtNi electrode was effectively employed for the real-time quantification of H2S released from breast cancer cells and mouse fibroblasts.

Titanium nanoparticle anchored functionalized MWCNTs for electrochemical detection of ractopamine in porcine samples with ultrahigh sensitivity.

We develop a disposable electrochemical sensor using a titanium nanoparticles (Ti NPs)-anchored functionalized multi-walled carbon nanotube (Ti@f-MWCNTs) composite as electrochemical sensing interface for the detection of ractopamine (RAC). The sensor demonstrated superior electrochemical sensing ability with a broad linear response range (0.01-185 µM) and ultralow detection limit (0.0038 µM). In addition, the stability, repeatability, reproducibility, and anti-interference ability of the Ti@f-MWCNTs sensor were satisfactory. The practicability of the sensor was effectively employed for the determination of RAC in porcine samples including pork, pig urine, and pig serum with substantial recoveries in the range of 92%-99% and a relative standard deviation of less than 5%.

Polyelectrolyte multilayer composite coating on 316 L stainless steel for controlled release of dual growth factors accelerating restoration of bone defects.

A composite coating of polyelectrolyte multilayers (PEMs) consisting of collagen, a chitosan barrier, and poly-γ-glutamic acid was fabricated using a spin coating technique to investigate and overcome the limited osseointegration capacity of 316 L stainless steel (316 L SS). To further enhance the biocompatibility, bone morphogenetic protein 2 (BMP-2) and basic fibroblast growth factor-2 (FGF-2) were loaded separately as dual growth factors, allowing for progressive drug release following the natural process of bone regeneration. The first burst release of FGF-2 triggered the proliferation of surrounding cells, and the subsequent release of BMP-2 stimulated their differentiation. The microstructure, surface potential, hardness, reduced Young's modulus, and wettability were assessed using scanning electron microscopy, nanoindentation, and water contact angle. The formation of apatite layers after immersion in simulated body fluid confirmed the bioactivity of this PEM. PEMs loaded with BMP-2 and FGF-2 showed a long sustained release of growth factors for up to 48 days. The biological properties were studied in vitro with rat bone mesenchymal stem cells (rBMSCs) and in vivo using a rat critical-sized calvarial defect model. PEMs loaded with growth factors further stimulated the proliferation and osteogenic differentiation of rBMSCs and the histology results indicated that new bone tissues could directly grow onto the PEMs. These findings suggest that PEM composite coating possesses significant potential for surface modification and long-term drug release of metallic implants to assist with bone restoration.

Nanostructured perovskite type gadolinium orthoferrite decorated RGO nanocomposite for the detection of nitrofurantoin in human urine and river water samples.

Nitrofurantoin (NFT) is mainly used in humans for the treatment of urinary tract infections. NFT is used as feed additives in animals, due to its broad antimicrobial activity. However, it shows more side effects on human health and the environment. Therefore low-cost, portable, and rapid sensors are necessary for the detection of NFT in real samples. Herein, we successfully developed an electrochemical sensor using a glassy carbon electrode (GCE) modified with gadolinium orthoferrite (GdFeO3) decorated on reduced graphene oxide (RGO) nanocomposite for the detection of NFT. The facile hydrothermal method was used to synthesis a novel GdFeO3/RGO nanocomposite, the morphological and structural characterization was confirmed by the FESEM, HRTEM, EDX, XRD, Raman, and XPS techniques. The formation mechanism of GdFeO3/RGO nanocomposite had been discussed. The effective intercalation of the nanostructured GdFeO3 to the RGO sheets leads to the significant enhancement in physicochemical properties such as electrical conductivity, electro-active surface area, structural stability, and electrochemical activity, which was observed from the EIS and CV experimental results. The electrochemical studies established that the developed GdFeO3/RGO sensor was highly sensitive and selective to NFT. Moreover, the GdFeO3/RGO sensor exhibits good sensitivity of 4.1985 µA µM-1 cm-2, a low detection limit (LOD) of 0.0153 µM and a linear range from 0.001 to 249 µM for NFT detection under optimized experimental conditions. In addition, the investigation of storage time on the CV response of the GdFeO3/RGO sensor indicates superior stability. Owing to these extraordinary analytical advantages, the as-fabricated sensor was applied to detect the NFT levels in human urine and river water samples with satisfactory results.

Highly Selective Electrochemical Sensor Based on Gadolinium Sulfide Rod-Embedded RGO for the Sensing of Carbofuran.

Nowadays, a lot of pesticides have been used in the agriculture field due to the global demand for food production. Carbofuran (CF) is the most commonly used carbamate compound that is responsible for the highest toxicity to humans compared to any other pesticide used in agricultural settings. Thus, rapid, portable, and low-cost sensors are needed for the detection of CF in the environment and food samples. Herein, we have successfully developed an electrochemical sensor using a glassy carbon electrode (GCE) modified with gadolinium sulfide (Gd2S3) and reduced graphene oxide (RGO) composite for the detection of carbofuran (CF). A novel Gd2S3/RGO composite was prepared by the facile hydrothermal route and confirmed by morphological and structural analyses such as field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray (EDX), powder X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS), and also the formation mechanism of Gd2S3/RGO composite was discussed. The desired electrical conductivity of Gd2S3 was enhanced by the RGO, which was estimated from the electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Electrochemical studies demonstrated that the developed Gd2S3/RGO sensor was highly sensitive and selective to CF. In addition, the Gd2S3/RGO sensor exhibits a low detection limit (LOD) and the linear ranges were 0.0128 and 0.001-1381 µM, respectively, for CF detection under optimized experimental conditions. Moreover, we also investigated the practical applicability of the sensor for CF detection in the environment and food samples.

Oral Cancer Theranostic Application of FeAu Bimetallic Nanoparticles Conjugated with MMP-1 Antibody.

Metastatic oral squamous cell carcinoma (SCC) displays a poor disease prognosis with a 5-year survival rate of 39%. Chemotherapy has emerged as the mainstream treatment against small clusters of cancer cells but poses more risks than benefits for metastatic cells due to the non-specificity and cytotoxicity. To overcome these obstacles, we conjugated antibodies specific for matrix metalloproteinase-1 (MMP-1), a prognostic biomarker of SCC, to iron-gold bimetallic nanoparticles (FeAu NPs) and explored the capability of this complex to target and limit SSC cell growth via magnetic field-induced hyperthermia. Our results showed that 4.32 ± 0.79 nm sized FeAu NPs were superparamagnetic in nature with a saturation magnetization (Ms) of 5.8 emu/g and elevated the media temperature to 45 °C, confirming the prospect to deliver hyperthermia. Furthermore, conjugation with MMP-1 antibodies resulted in a 3.07-fold higher uptake in HSC-3 (human tongue squamous cell carcinoma) cells as compared to L929 (fibroblast) cells, which translated to a 5-fold decrease in cell viability, confirming SCC targeting. Finally, upon magnetic stimulation, MMP-1-FeAu NPs conjugate triggered 89% HSC-3 cellular death, confirming the efficacy of antibody-conjugated nanoparticles in limiting SCC growth. The synergistic effect of biomarker-specific antibodies and magnetic nanoparticle-induced hyperthermia may open new doors towards SCC targeting for improved disease prognosis.

One-Pot Sustainable Synthesis of Ce2S3/Gum Arabic Carbon Flower Nanocomposites for the Detection of Insecticide Imidacloprid.

Investigating ecofriendly sustainable materials with excellent electrocatalytic activity is a pivotal approach for the analysis field. The present work reports on the preparation of novel three-dimensional (3D) cerium sulfide with gum arabic carbon flowers (Ce2S3/GACFs) via the hydrothermal method by using l-cysteine as a sulfur source, binding, and reducing agents. The intensive characterization techniques were utilized to corroborate the structural moiety, morphology, and size of Ce2S3/GACFs. The obtained 3D Ce2S3/GACF construction has excellent active sites, and hence it prevents the accumulation of carbon flowers. Furthermore, the obtained Ce2S3/GACF/glassy carbon electrode (GCE) could afford a very high electrocatalytic activity, possessing an exceedingly low detection limit of 32 nM, the high sensitivity of 2.65 µA µM-1 cm-2, good repeatability, and high stability for the detection of insecticide imidacloprid (IMC). The Ce2S3/GACF/GCE also provides a wide linear range of 0.05-1266 µM toward IMC detection. The excellent recovery results (90-99.3%) are achieved by using various spiked real food samples at Ce2S3/GACF/GCE. Confidently, this work gives up novel construction of 3D metal-carbon-based bioderived material for its catalytic application in the future.

Electrochemical detection of thiamethoxam in food samples based on Co3O4 Nanoparticle@Graphitic carbon nitride composite.

Thiamethoxam is a class of neonicotinoid insecticide widely used in agriculture. Due to their high water solubility, thiamethoxam can be transported to surface waters and have the potential to be toxic to human life. Herein, a simple and robust method is presented for the detection of thiamethoxam based on hydrothermally synthesized nanoparticles of cobalt oxide into the graphitic carbon nitride composite (Co3O4@g-C3N4 NC). The materials were well characterized by XRD, FT-IR, XPS, FESEM, HRTEM, EDX, and UV-vis which provide crystalline nature, structure, and composition. The impedance measurement shows an intimate electrode/electrolyte interface by casting Co3O4@g-C3N4 onto a screen-printed carbon electrode (SPCE), delivering an interfacial resistance as low as 12.5 Ωcm2. The cyclic voltammetry and differential pulse voltammetry measurements exhibit the nanocomposite as a superior electrocatalyst for the electrochemical detection of thiamethoxam and achieved a low detection limit of 4.9 nM with a wide linear range of 0.01-420 µM. The present work also demonstrates a promising strategy for electrochemical detection of thiamethoxam in real samples such as potato and brown rice.

Carbon fibers coated with urchin-like copper sulfide for nonenzymatic voltammetric sensing of glucose.

Urchin-like CuS was grown on xanthan gum-derived carbon nanofibers to obtain a sensor for enzyme-free electrochemical sensing of glucose. The unique nanostructure of the sensor provides a large specific surface, more electrocatalytically active sites, and high electrical conductivity. The voltammetric response to glucose, best measured at around 57 mV (vs. Ag/AgCl (E/V)) in 0.1 M NaOH solution, covers two linear ranges, one from 0.1-125 µM, another from 0.16 to 1.2 mM. The sensitivity is quite high (23.7 µA mM-1 cm-2), and the detection limit is low (19 nM at S/N = 3). The sensor has high selectivity against potentially interfering molecules such as fructose, appreciable operational stability, excellent durability, and good repeatability (with relative standard deviations of 2.3%). It was successfully applied to the determination of glucose in diluted serum samples. Graphical abstractSchematic representation of electrochemical detection of glucose based on the use of a screen printed carbon electrode (SPCE) modified with CuS and xanthan gum-derived carbon nanofibers (XGCNFs).

A core-shell molybdenum nanoparticles entrapped f-MWCNTs hybrid nanostructured material based non-enzymatic biosensor for electrochemical detection of dopamine neurotransmitter in biological samples.

Dopamine (DA) is a critical neurotransmitter and has been known to be liable for several neurological diseases. Hence, its sensitive and selective detection is essential for the early diagnosis of diseases related to abnormal levels of DA. In this study, we reported novel molybdenum nanoparticles self-supported functionalized multiwalled carbon nanotubes (Mo NPs@f-MWCNTs) based core-shell hybrid nanomaterial with an average diameter of 40-45 nm was found to be the best for electrochemical DA detection. The Mo NPs@f-MWCNTs hybrid material possesses tremendous superiority in the DA sensing is mainly due to the large surface area and numerous electroactive sites. The morphological and structural characteristics of the as-synthesized hybrid nanomaterial were examined by XRD, Raman, FE-SEM, HR-TEM, EDX. The electrochemical characteristics and catalytic behavior of the as-prepared Mo NPs@f-MWCNTs modified screen-printed carbon electrode for the determination of DA were systematically investigated via electrochemical impedance spectroscopy, cyclic voltammetry, and amperometry. The results demonstrate that the developed DA biosensor exhibit a low detection limit of 1.26 nM, excellent linear response of 0.01 µM to 1609 µM with good sensitivity of 4.925 µA µM-1 cm-2. We proposed outstanding appreciable stability sensor was expressed to the real-time detection of DA in the real sample analysis of rat brain, human blood serum, and DA hydrochloride injection.