Exploring Nanomaterials for Hydrogen Storage: Advances, Challenges, and Perspectives.

Hydrogen energy heralded for its environmentally friendly, renewable, efficient, and cost-effective attributes, stands poised as the primary alternative to fossil fuels in the future. Despite its great potential, the low volumetric density presents a formidable challenge in hydrogen storage. Addressing this challenge necessitates exploring effective storage techniques for a sustainable hydrogen economy. Solid-state hydrogen storage in nanomaterials (physically or chemically) holds promise for achieving large-scale hydrogen storage applications. Such approaches offer benefits, including safety, compactness, lightness, reversibility, and efficient generation of pure hydrogen fuel under mild conditions. This article presents solid-state nanomaterials, specifically nanoporous carbons (activated carbon, carbon fibers), metal-organic frameworks, covalently connected frameworks, nanoporous organic polymers, and nanoscale metal hydrides. Furthermore, new developments in hydrogen fuel cell technology for stationary and mobile applications have been demonstrated. The review outlines significant advancements thus far, identifies key barriers to practical implementation, and presents a perspective for future sustainable energy research. It concludes with recommendations to enhance hydrogen storage performance for cost-effective and long-lasting utilization.

Synthesis of NiMn2O4/PANI nanosized composite with increased specific capacitance for energy storage applications.

Polyaniline (PANI) stands out as a highly promising conducting polymer with potential for advanced utilization in high-performance pseudocapacitors. Therefore, there exists a pressing need to bolster the structural durability of PANI, achievable by developing composite materials that can enhance its viability for supercapacitor applications. In this particular study, a pioneering approach was undertaken to produce a novel NiMn2O4/PANI supercapacitor electrode material. A comprehensive array of analytical techniques was employed to ascertain the structural configuration, morphology, oxidation states of elements, composition, and surface characteristics of the electrode material. The electrochemical evaluation of the NiMn2O4/PANI composite shows a specific capacitance (Cs) of 1530 ± 2 F g-1 at 1 A g-1. Significantly, the composite material displays an outstanding 93.61% retention of its capacity after an extensive 10 000 cycles, signifying remarkable cycling stability, while the 2-electrode configuration reveals a Cs value of 764 F g-1 at 5 mV s-1 and 826 F g-1 at 1 A g-1 with a smaller charge transfer resistance (Rct) value of 0.67 Ω. Chronoamperometric tests showed excellent stability of the fabricated material up to 50 h. This significant advancement bears immense promise for its potential implementation in high-efficiency energy storage systems and heralds a new phase in the development of supercapacitor technology with improved stability and performance metrics.

Synergistic effect of a bamboo-like Bi2S3 covered Sm2O3 nanocomposite (Bi2S3-Sm2O3) for enhanced alkaline OER.

The availability of hydrogen energy from water splitting through the electrocatalytic route is strongly dependent on the efficiency, durability, and cost of the electrocatalysts. Herein, a novel Bi2S3-covered Sm2O3 (Bi2S3-Sm2O3) nanocomposite electrocatalyst was developed by a hydrothermal route for the oxygen evolution reaction (OER). The electrochemical properties were studied in 1.00 mol KOH solution after coating the target material on the stainless-steel substrate (SS). Physical analysis via XRD, FTIR, IV, TEM/EDX, and XPS revealed that the Bi2S3-Sm2O3 composite possesses metallic surface states, thereby displaying unconventional electron dynamics and purity of phases. The Bi2S3-Sm2O3 composite shows outstanding OER activity with a low overpotential of 197 mV and a Tafel slope of 74 mV dec-1 at a 10 mA cm-2 current density as compared to pure Bi2S3 and Sm2O3. Meanwhile, the composite catalyst retains high stability even after 100 h of the chronoamperometry test. Thus, this work unveils a new avenue for the speedy flow of electrons, which is attributed to the synergetic effect between Bi2S3 and Sm2O3, as well as enriched interfacial defects, which exhibit greater oxygen adsorption capability with improved electronic assemblies in the active interfacial region. In addition, the introduced porous structure in core-shell Bi2S3-Sm2O3 provides extraordinary electrical properties. Thus, this article offers a realistic framework for electrochemical energy generation.

Solvothermally designed Pr-MOF/Fe2O3 based nanocomposites for efficient electrocatalytic water splitting.

To meet the energy demand of modern civilization, efforts to find renewable, safe, and highly effective fuel generation are still a big challenge. The oxygen evolution reaction (OER) is one of many modern technologies for hydrogen generation, and a number of new electrode materials have been created to increase the effectiveness of O2 evolution. This project utilizes a range of high performance nanomaterials, such as Pr-MOF, Fe2O3, and Pr-MOF/Fe2O3, to carry out the oxygen evolution reaction. This study shows that Pr-MOF/Fe2O3 exhibits exceptional electrocatalytic activity in alkaline solution with 238 mV overpotential at the current density of 10 mA cm-2 and a Tafel slope of 37 mV dec-1 which is much lower when compared to pure Pr-MOF and Fe2O3. The enhanced electrochemical results are due to the higher electrochemical surface area of 237 cm2. This work will lay the foundation for an approach to enhance the crystalline nature of surface-active nanoparticles made from rare earth MOFs for a range of electrochemical energy applications.

Facile synthesis of a CuSe/PVP nanocomposite for ultrasensitive non-enzymatic glucose biosensing.

Non-enzymatic glucose biosensors show high sensitivity, lower response time, wide linear range and low cost. Copper based composites show excellent electrocatalytic tunability and lead to a better charge transfer in electrochemical non-enzymatic glucose biosensors. In this work, a nanocomposite of polyvinylpyrrolidone (PVP) and copper selenide was synthesized by a facile one pot sol gel method. Synthesized nanomaterials were characterized by XRD, FTIR, UV-visible spectroscopy, SEM, EDS and XPS techniques. Electrochemical behavior was analyzed by cyclic voltammetry (CV), electrochemical impendence (EIS) and chronoamperometry techniques. XRD analysis revealed a hexagonal structure and crystalline nature of CuSe/PVP. FTIR spectra depicted C-N bonding at 1284 cm-1 and C[double bond, length as m-dash]O stretching at 1634 cm-1, which indicated the presence of PVP in the nanocomposite. Stretching at 823 cm-1 was attributed to the presence of copper selenide. UV-visible absorption indicated the bandgap of copper selenide/PVP at 2.7 eV. SEM analysis revealed a flake like morphology of CuSe/PVP. EDS and XPS analysis confirmed the presence of copper and selenium in the prepared nanocomposite. Prior to employing for biosensing applications, it is important to evaluate the antibacterial activity of nanomaterials for long term use in biological in vitro testing. These materials have shown an efficient inhibition zone of 26 mm against Gram negative Pseudomonas at 50 µg ml-1 and MIC value of 10 µg ml-1. Cyclic voltammetry shows that CuSe/PVP is a promising biosensor for monitoring glucose levels in a wide linear range of 0.5 mM to 3 mM at an excellent sensitivity of 13 450 µA mM-1 cm-2 with an LOD of 0.223 µM. Chronoamperometry measurements revealed a selective behavior of CuSe/PVP for glucose biosensing amongst ascorbic acid and dopamine as common interfering molecules. The nanocomposite was stable after 8 repeated cycles with 92% retention for glucose sensing capacity. This is attributed to the stable nature of the CuSe/PVP nanocomposite as well as higher surface area of available active sites. Herein the CuSe/PVP nanocomposite offered reasonable selectivity, high sensitivity wide linear range with very low LOD, as well as being abundant in nature, this Cu based biosensor has promising applications for future point of care tests (POCT).

One-pot hydrothermal synthesis of a carbon quantum dot/CaFe2O4 hybrid nanocomposite for carcinogenic Congo red dye degradation.

Semiconductor materials show a restricted degradation response to organic pollutants due to limited photocatalytic activity under visible light. Therefore, researchers have devoted much attention to novel and effective nanocomposite materials. For the first time, herein, a novel nano-sized semiconductor calcium ferrite modified by carbon quantum dots (CaFe2O4/CQDs) photocatalyst is fabricated via simple hydrothermal treatment for the degradation of aromatic dye using a visible light source. The crystalline nature, structure, morphology, and optical parameters of each of the synthesized materials were investigated using X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and UV-visible spectroscopy. The nanocomposite exhibits excellent photocatalytic performance (90% degradation) against Congo red (CR) dye. In addition, a mechanism for CaFe2O4/CQDs improving photocatalytic performance has been proposed. The CQDs in the CaFe2O4/CQD nanocomposite are considered to act as an electron pool and transporter, as well as a strong energy transfer material, during photocatalysis. CaFe2O4/CQDs appear to be a promising and cost-effective nanocomposite for dye-contaminated water purification, according to the findings of this study.

Polarity reversal for enhanced in-situ electrochemical synthesis of H2O2 over banana-peel derived biochar cathode for water remediation.

The fabrication of a cost-efficient cathode is critical for in-situ electrochemical generation of hydrogen peroxide (H2O2) to remove persistent organic pollutants from groundwater. Herein, we tested a stainless-steel (SS) mesh wrapped banana-peel derived biochar (BB) cathode for in-situ H2O2 electrogeneration to degrade bromophenol blue (BPB) and Congo red (CR) dyes. Furthermore, polarity reversal is evaluated for the activation of BB surface via introduction of various oxygen containing functionalities that serve as active sites for the oxygen reduction reaction (ORR) to generate H2O2. Various parameters including the BB mass, current, as well as the solution pH have been optimized to evaluate the cathode performance for efficient H2O2 generation. The results reveal formation of up to 9.4 mg/L H2O2 using 2.0 g BB and 100 mA current in neutral pH with no external oxygen supply with a manganese doped tin oxide deposited nickel foam (Mn-SnO2@NF) anode to facilitate the oxygen evolution reaction (OER). This iron-free electrofenton (EF) like process enabled by the SSBB cathode facilitates efficient degradation of BPB and CR dyes with 87.44 and 83.63% removal efficiency, respectively after 60 min. A prolonged stability test over 10 cycles demonstrates the effectiveness of polarity reversal toward continued removal efficiency as an added advantage. Moreover, Mn-SnO2@NF anode used for the OER was also replaced with stainless steel (SS) mesh anode to investigate the effect of oxygen evolution on H2O2 generation. Although Mn-SnO2@NF anode exhibits better oxygen evolution potential with reduced Tafel slope, SS mesh anode is discussed to be more cost-efficient for further studies.

Facile synthesis of the SnTe/SnSe binary nanocomposite via a hydrothermal route for flexible solid-state supercapacitors.

Environmental degradation and energy shortage are the two biggest problems facing the world right now. Because of the limited supply of non-renewable sources, the production of environment-friendly energy and its storage has gained significant importance. Pseudocapacitors have lately caught the interest of energy specialists due to their greater energy/power density and prolonged cycle life. In this work, binding-free SnTe/SnSe (STSS) electrodes deposited onto Ni foam (NF) as the conductive substrate have been developed by a facile hydrothermal route for supercapacitor applications. Several analytical tools were utilized to study the morphological, structural and textural characteristics. The electrochemical results obtained from a three-electrode system suggest that the STSS electrode material exhibits great specific capacitance (C s) of 1276 F g-1, specific energy (E d) of 46.45 W h kg-1 and specific power (P d) of 256 W kg-1 @ 1 A g-1. The results of C dl indicate that the STSS (31.28 mF) has a larger C dl value than those of SnTe (23.22 mF) and SnSe (26.35 mF). The analysis of electrochemical stability indicates that the STSS displays structural stability over 5000 cycles with a maximum capacitance retention of 96%. The Nyquist plot profile displayed a smaller R ct value for STSS (0.89 Ω) than SnSe (1.13 Ω) and SnTe (1.97 Ω). The symmetric behavior of STSS was determined in 2.0 M potassium hydroxide. The results reveal that this material has a specific capacitance of 537.72 F g-1 and specific energy of 78.32 W h kg-1. These findings suggest that the STSS electrode might serve as a potential candidate for supercapacitors and other energy-saving equipment.

Amide Functionalized Mesoporous MOF LOCOM-1 as a Stable Highly Active Basic Catalyst for Knoevenagel Condensation Reaction.

Acyl-amide is extensively used as functional group and is a superior contender for the design of MOFs with the guest accessible functional organic sites. A novel acyl-amide-containing tetracarboxylate ligand, bis(3,5-dicarboxy-pheny1)terephthalamide, has been successfully synthesized. The H4L linker has some fascinating attributes as follows: (i) four carboxylate moieties as the coordination sites confirm affluent coordination approaches to figure a diversity of structure; (ii) two acyl-amide groups as the guest interaction sites can engender guest molecules integrated into the MOF networks through H-bonding interfaces and have a possibility to act as functional organic sites for the condensation reaction. A mesoporous MOF ([Cu2(L)(H2O)3]·4DMF·6H2O) has been prepared in order to produce the amide FOS within the MOF, which will work as guest accessible sites. The prepared MOF was characterized by CHN analysis, PXRD, FTIR spectroscopy, and SEM analysis. The MOF showed superior catalytic activity for Knoevenagel condensation. The catalytic system endures a broad variety of the functional groups and presents high to modest yields of aldehydes containing electron withdrawing groups (4-chloro, 4-fluoro, 4-nitro), offering a yield > 98 in less reaction time as compared to aldehydes with electron donationg groups (4-methyl). The amide decorated MOF (LOCOM-1-) as a heterogeneous catalyst can be simply recovered by centrifugation and recycled again without a flagrant loss of its catalytic efficiency.

Fabrication of fullerene-supported La2O3-C60 nanocomposites: dual-functional materials for photocatalysis and supercapacitor electrodes.

Nowadays, water pollution and energy crises worldwide force researchers to develop multi-functional and highly efficient nanomaterials. In this scenario, the present work reports a dual-functional La2O3-C60 nanocomposite fabricated by a simple solution method. The grown nanomaterial worked as an efficient photocatalyst and proficient electrode material for supercapacitors. The physical and electrochemical properties were studied by state-of-the-art techniques. XRD, Raman spectroscopy, and FTIR spectroscopy confirmed the formation of the La2O3-C60 nanocomposite with TEM nano-graphs, and EDX mapping exhibits the loading of C60 on La2O3 particles. XPS confirmed the presence of varying oxidation states of La3+/La2+. The electrochemical capacitive properties were tested by CV, EIS, GCD, ECSA, and LSV, which indicated that the La2O3-C60 nanocomposite can be effectively used as an electrode material for durable and efficient supercapacitors. The photocatalytic test using methylene blue (MB) dye revealed the complete photodegradation of the MB dye under UV light irradiation after 30 min by a La2O3-C60 catalyst with a reusability up to 7 cycles. The lower energy bandgap, presence of deep-level emissions, and lower recombination rate of photoinduced charge carriers in the La2O3-C60 nanocomposite than those of bare La2O3 are responsible for enhanced photocatalytic activity with low-power UV irradiation. The fabrication of multi-functional and highly efficient electrode materials and photocatalysts such as La2O3-C60 nanocomposites is beneficial for the energy industry and environmental remediation applications.

A facile synthesis of CeO2 from the GO@Ce-MOF precursor and its efficient performance in the oxygen evolution reaction.

Electrochemical water splitting has enticed fascinating consideration as a key conduit for the advancement of renewable energy systems. Fabricating adequate electrocatalysts for water splitting is fervently preferred to curtail their overpotentials and hasten practical utilizations. In this work, a series of Ce-MOF, GO@Ce-MOF, calcinated Ce-MOF, and calcinated GO@Ce-MOF were synthesized and used as high-proficient electrocatalysts for the oxygen evolution reaction. The physicochemical characteristics of the prepared samples were measured by diverse analytical techniques including SEM, HRTEM, FTIR, BET, XPS, XRD, and EDX. All materials underwent cyclic voltammetry tests and were evaluated by electrochemical impedance spectroscopy and oxygen evolution reaction. Ce-MOF, GO@Ce-MOF, calcinated Ce-MOF, and calcinated GO@Ce-MOF have remarkable properties such as enhanced specific surface area, improved catalytic performance, and outstanding permanency in the alkaline solution (KOH). These factors upsurge ECSA and intensify the OER performance of the prepared materials. More exposed surface active-sites present in calcinated GO@Ce-MOF could be the logic for superior electrocatalytic activity. Chronoamperometry of the catalyst for 15°h divulges long-term stability of Ce-MOF during OER. Impedance measurements indicate higher conductivity of synthesized catalysts, facilitating the charge transfer reaction during electrochemical water splitting. This study will open up a new itinerary for conspiring highly ordered MOF-based surface active resources for distinct electrochemical energy applications.

Human serum N-glycome profiling via the newly developed asparagine immobilized cellulose/polymer nanohybrid.

Human serum N-linked glycans expression levels change during the disease progression. The low abundance, structural diversity, and coexisting matrices hinder their detection in mass spectrometry analysis. Considering the hydrophilic nature of N-glycans, cellulose/polymer (1,2-Epoxy-5-hexene) nanohybrid is fabricated with oxirane groups functionalized of asparagine to develop solid phase extraction based hydrophilic interaction liquid chromatography sorbent (cellulose/1,2-Epoxy-5-hexene/asparagine). The morphology, elemental analysis, and surface properties are studied through scanning electron microscopy, energy dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy. The large surface area of cellulose/polymer nanohybrid (2.09 × 102  m2 /g) facilitates the high density of asparagine immobilization resulting in better hydrophilic interaction liquid chromatography enrichment under optimized conditions. The enrichment capability of nanohybrid/asparagine is assessed by the N-Linked glycans released from ovalbumin and immunoglobulin G where 23 and 13 N-glycans are detected respectively. The nanohybrid/asparagine shows selectivity of 1:1200 with spiked bovine serum albumin and sensitivity down to 100 attomole. Human serum profiling for N-glycans identifies 52 glycan structures. This new enrichment strategy enriches serum N-linked glycans in the presence of salts, proteins, endogenous serum peptides, and so forth.

Electrochemical Sensing Platform Based on Functionalized Multi-Walled Carbon Nanotubes and Metal Oxide for the Detection and Degradation Studies of Orange II Dye.

Textile industry effluents are heavily contaminated with dyes. The discharge of these toxic dyes into waterbodies poses a serious threat to aquatic flora and fauna. The ultimate entrance of these toxins from thereon into the food chain affects the primary and secondary consumers. Therefore, the adoption of a sustainable solution for protection against the detrimental effects associated with adulterated water is an immediate need of the hour. To address the severity of the issue, the present work aims to design an electrochemical sensing platform by modifying the glassy carbon electrode (GCE) with zinc oxide nanoparticles and amino group-functionalized multi-walled carbon nanotubes (NH2-fMWCNTs) for the detection of Orange II, which is a toxic azo dye. Zinc oxide nanoparticles facilitate electron transfer between the transducer and the analyte. While, the positively charged NH2-fMWCNTs in acidic medium help in preconcentration of negatively charged analyte molecules at the electrode/electrolyte interface. The modification of the GCE catalyzed the oxidation of Orange II, as evidenced by the negative shift of the oxidation potential and enhancement in peak current intensity. Square wave voltammetry was used to optimize various experimental conditions, such as the supporting electrolyte, pH of the electrolyte, deposition potential, and deposition time for the best performance of the designed sensor. Under the optimized conditions, the detection limit and quantification of the designed sensor were found to be 0.57 and 1.92 nM, respectively. The catalytic degradation studies of Orange II was shown to be facilitated by titanium dioxide, which acted as a photocatalyst. The addition of hydrogen peroxide further promoted the extent and rate of degradation of dye. The breakdown of Orange II was probed by the designed sensing platform electrochemically and also by UV-visible spectroscopy. The dye degraded up to 92% by following pseudo-first-order kinetics.

Facile hydrothermal synthesis of NiTe nanorods for non-enzymatic electrochemical sensing of whole blood hemoglobin in pregnant anemic women.

Electrochemical sensing methods monitor biomolecules because of their specificity, rapid response, lower cost, and automation. Hemoglobin is an abundant protein in the human body and is correlated with various physiological processes. Levels of hemoglobin in blood are associated with anemia in pregnant women. In this research, a non-enzymatic sensor based on NiTe nanorods is developed for the detection and quantification of hemoglobin (Hb) from anemic pregnant patients. NiTe nanorods are synthesized by the single-step method. After characterizing the material, sensing parameters such as the effect of scan rate, pH, concentration, and interferences are optimized using standard hemoglobin samples. Linearity, the limit of detection (LOD), and the limit of quantification (LOQ) for NiTe nanorods are 0.99698, 0.012 nM, and 0.04 nM, respectively. Stability is measured by cyclic chronoamperometry (12 h) and voltammetry (100 cycles). Recovery of hemoglobin from blood samples is in the range of 63-90%. NiTe nanorods quantitatively determine hemoglobin from the blood samples of anemic pregnant women.

Iminodiacetic acid (IDA)-generated mesoporous nanopolymer: a template to relate surface area, hydrophilicity, and glycopeptides enrichment.

A three-step strategy is introduced to develop inherent iminodiacetic (IDA)-functionalized nanopolymer. SEM micrographs show homogenous spherical beads with a particle size of 500 nm. Further modification to COOH-functionalized 1,2-epoxy-5-hexene/DVB mesoporous nanopolymer enriches glycopeptides via hydrophilic interactions followed by their MS determination. Significantly high BET surface area 433.4336 m2 g-1 contributes to the improved surface hydrophilicity which is also shown by high concentration of ionizable carboxylic acids, 14.59 ± 0.25 mmol g-1. Measured surface area is the highest among DVB-based polymers and in general much higher in comparison to the previously reported BET surface areas of co-polymers, terpolymers, MOFs, and graphene-based composites. Thirty-one, 19, and 16 N-glycopeptides are enriched/identified by nanopolymer beads from tryptic digests of immunoglobulin G, horseradish peroxidase, and chicken avidin, respectively, without additional desalting steps. Material exhibits high selectivity (1:400 IgG:BSA), sensitivity (down to 0.1 fmol), regeneration ability up to three cycles, and batch-to-batch reproducibility (RSD > 1%). Furthermore, from 1 µL of digested human serum, 343 N-glycopeptide characteristics of 134 glycoproteins including 30 FDA-approved serum biomarkers are identified via nano-LC-MS/MS. The developed strategy to self-generate IDA on polymeric surface with improved surface area, porosity, and ordered morphology is insignia of its potential as chromatographic tool contributing to future developments in large-scale biomedical glycoproteomics studies.

Base-Promoted One-Pot Synthesis of Pyridine Derivatives via Aromatic Alkyne Annulation Using Benzamides as Nitrogen Source.

In the presence of Cs2CO3, the first simple, efficient, and one-pot procedure for the synthesis of 3,5-diaryl pyridines via a variety of aromatic terminal alkynes with benzamides as the nitrogen source in sulfolane is described. The formation of pyridine derivatives accompanies the outcome of 1,3-diaryl propenes, which are also useful intermediates in organic synthesis. Thus, pyridine ring results from a formal [2+2+1+1] cyclocondensation of three alkynes with benzamides, and one of the alkynes provides one carbon, whilst benzamides provide a nitrogen source only. A new transformation of alkynes as well as new utility of benzamide are found in this work.

Apo-H (beta-2-glycoprotein) intact N-glycan analysis by MALDI-TOF-MS using sialic acid derivatization.

Apo-H is a plasma glycoprotein. Nearly 19% of the molecular weight of this protein is composed of glycans. Up- and down-regulation and structural changes in protein glycans provide diagnostic value for disease detection. Here, an efficient, sensitive, and optimized method is developed for Apo-H N-glycans analysis by MALDI-TOF-MS in positive mode. This bioanalytical method includes sample preparation, sample purification, and detection. An Apo-H enrichment method is developed using standard proteins by anti-Apo-H beads followed by enrichment from plasma samples. SDS-PAGE confirms the Apo-H protein enrichment, which is further verified by LC-MS/MS analysis. The lower ionization efficiency of sialylated glycan hampers their analysis by MALDI-MS. For this, stabilization of sialic acids is done by selective derivatization of carboxyl groups to differentiate between α(2,3)- and α(2,6)-linked sialic acids. Glycans are further purified by HILIC-SPE and analyzed by MALDI-MS. Several branched bi- and tri-antennary glycans with fucosylation and sialylation are identified. The reproducibility of the developed method is tested by analyzing multiple replicates of human plasma, where the same glycans are consistently identified. This method could be applied for the Apo-H glycan profiling of large clinical cohorts for diagnostic purposes.

Tin derived antimony/nitrogen-doped porous carbon (Sb/NPC) composite for electrochemical sensing of albumin from hepatocellular carcinoma patients.

An electrochemical sensor based on an antimony/nitrogen-doped porous carbon (Sb/NPC) composite has been developed for the quantitative detection of albumin from hepatocellular carcinoma (HCC) patients. Sb/NPC is hydrothermally synthesized from Sn/NPC precursors. The synthesized precursor (Sn/NPC) and the product (Sb/NPC) are characterized by XRD, FTIR, TGA, UV/Vis, SEM, and AFM. Cyclic voltammetry, chronoamperometry, and electrochemical impedance studies are used to investigate the electrochemical performance of Sb/NPC-GCE. Sb/NPC-GCE detects albumin at physiological pH of 7.4 in the potential range 0.92 V and 0.09 V for oxidation and reduction, respectively. LOD and recovery of Sb/NPC-GCE for the determination of albumin are 0.13 ng.mL-1 and 66.6 ± 0.97-100 ± 2.73%, respectively. Chronoamperometry of the modified working electrode demonstrates its stability for 14 h, indicating its reusability and reproducibility. Sb/NPC-GCE is a selective sensor for albumin detection in the presence of interfering species. The electrode has been applied for albumin detection in human serum samples of HCC patients. A negative correlation of albumin with alpha-fetoprotein levels in HCC patients is observed by statistical analysis.

Graphene oxide-metal oxide nanocomposites for on-target enrichment and analysis of phosphorylated biomolecules.

The surface of matrix-assisted laser desorption/ionization mass spectrometry target is modified for improved signal strength and detection of analytes. The developed method includes on-target enrichment and detection of phosphopeptides/phospholipids using graphene oxide-lanthanide metal oxides (samarium, gadolinium, dysprosium, and erbium) nanocomposites. Enriched phosphopeptides are detected using material enhanced laser desorption/ionization mass spectrometry and phospholipids by laser desorption/ionization-mass spectrometry. Nanocomposites are prepared using graphene oxide with respective metal salts at high pH. They are characterized for nano-morphology, chemistry, porosity, composition, crystallinity, and thermal stability. Phosphopeptides enrichment protocol is developed and optimized for tryptic ß-casein digest and that of phospholipids by phosphatidylcholine standard. Statistical analyses of phosphopeptides and phospholipids from milk show overlapping results for gadolinium, dysprosium, and erbium oxide nanocomposites. GO-Gd2 O3 has better enrichment efficiency and application as LDI material. Selectivity for GO-Dy2 O3 is 1:2500, for GO-Sm2 O3 is 1:3500, and 1:4000 for GO-Gd2 O3 . GO-Er2 O3 has a sensitivity of 25 fmol, whereas the highest sensitivity is down to 0.5 fmol for GO-Gd2 O3 . On-target enrichment is batch to batch reproducible with a standard deviation of <1, reduced time of enrichment to 10 min, and ease of operation compared to solid-phase batch extraction. The developed method enriches serum phosphopeptides characteristic of cancer-related phosphoproteins.

Quantitative determination of creatinine from serum of prostate cancer patients by N-doped porous carbon antimony (Sb/NPC) nanoparticles.

Creatinine is an indicator of hindrance in urination and renal insufficiency. Creatinine levels are the marker of the late stages of prostate cancer. Early and sensitive detection of creatinine can reduce deaths associated with prostate cancer. In this work, nitrogen-doped porous carbon antimony (Sb/NPC) nanoparticles are fabricated to be employed as a non-enzymatic biosensor. Sb/NPC has promising redox activity and is synthesized by a two-step reaction using low-cost precursors. Electrochemical sensing by Sb/NPC is conducted for standard creatinine solutions on a three-electrodes system. Cyclic voltammetry, amperometry, and electrochemical impedance spectroscopy are used to sense creatinine. LOD and LOQ of the Sb/NPC modified electrode are 0.74 µM and 2.4 µM, respectively. This electrode system analyzes creatinine in the serum of prostate cancer patients who have elevated PSA levels. More than 90% creatinine is recovered from a spiked serum sample of a prostate cancer patient. A direct relation is observed between PSA levels and creatinine levels in prostate cancer. The developed cyclic voltammetric setup detects trace concentrations of creatinine in serum.