Adsorptive removal of oxytetracycline using MnO2-engineered pine-cone biochar: thermodynamic and kinetic investigation and process optimization.

Indiscriminate use of oxytetracycline is linked to the development of antibiotic-resistant genes, posing a serious threat to human health and ecosystem balance. This article reports the adsorptive elimination of oxytetracycline (OTC) from aqueous solution using a newly developed MnO2-modified pine-cone biochar (MnO2/PCBC). The MnO2/PCBC was characterized using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, CHNS analyzer, inductively coupled plasma-optical emission spectroscopy, and Brunauer-Emmett-Teller N2 adsorption analyzer. Batch adsorption experiments, designed using the central composite design framework of response surface methodology, were conducted to investigate the influence of process variables on the adsorption of OTC onto MnO2/PCBC. The optimized conditions for achieving maximum removal (88.1%) were found to be at pH 8, MnO2/PCBC dose 0.44 g/L, initial OTC concentration 200 mg/L, and temperature 303 K. The adsorption process follows Langmuir (R2=0.95) and Freundlich (R2=0.95) isotherms and pseudo-second-order (R2=0.99) adsorption kinetics. The adsorption process was found to be endothermic (ΔH0 = 33.04 kJ/mol) and spontaneous in nature (ΔG0 from -1.33 kJ/mol at 283 K to -5.65 kJ/mol at 313 K). The synthesized MnO2/PCBC could be recycled and reused for OTC removal with a percentage removal of around 80% after fifth cycle. The results indicate an effective removal of oxytetracycline with only 0.44 g/L MnO2/PCBC with maximum adsorption capacity of 357.14 mg/g which demonstrates improved performance in comparison to many adsorbents reported in literature. This implies that MnO2/PCBC offers potential to be developed into a cost-effective technique for antibiotic removal from water.

A review on Japanese Encephalitis virus emergence, pathogenesis and detection: From conventional diagnostics to emerging rapid detection techniques.

The virus known as Japanese Encephalitis (JEV) is among the common viral persisting Encephalitis caused by Flavivirus around the Globe, especially in Southeast Asian nations. JEV may be a leading reason for neurological illness in humans, with an estimated 70,000 human cases and 10,000 fatalities per annum. The conventional methods like PRNT (Plaque Reduction Neutralization Test), ELISA (Enzyme-linked immunosorbent assay) RT-PCR (reverse transcription-polymerase chain reaction), and virus isolation are few commercial tests being availed these days, but they have a variety of drawbacks, including being extremely expensive, time-consuming, and requiring expertise. Therefore, researches are being made in the development of improved inexpensive, shorter, sensitive, and time-saving strategies to diagnose the Japanese Encephalitis Virus. A number of these researches encompass the employment of immunosensors, electrochemical sensors and along with the applications of nanotechnology to create highly sensitive detecting device. This review article is based on contemporary breakthroughs in diagnosing Japanese Encephalitis Virus, which are crucial in severing the connection between the propagation of zoonotic disease into the current race, where humans function as dead-end hosts.

Treatment of textile industry wastewater by using high-performance forward osmosis membrane tailored with alpha-manganese dioxide nanoparticles for fertigation.

Forward osmosis (FO) technology has been acknowledged as an energy-efficient cutting-edge water treatment innovation; however, the inefficient performance of polymer-based membranes remains a tailback in the practical utilization of FO. A significant issue in FO is membrane fouling, which negatively influences the flux efficiency, working expenses and membrane life expectancy. Membranes having high water flux and minimum reverse solute flux at low operating pressures are the ideal membranes for this process. This study reports a thin-film nanocomposite (TFNC) membrane for the treatment of textile industry wastewater utilizing fertilizer as draw solution fabricated via the phase inversion process. The chemical structure and morphology of the synthesized manganese oxide (MnO2) incorporated membrane were studied by various characterization techniques like X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy-energy-dispersive X-ray spectroscopy, contact angle and gravimetry. The outcomes demonstrated that the nanoparticles were bonded to cellulose acetate polymer via covalent bonds and showed very hydrophilic membrane surface, along with an increased osmotic water flux of 52.5 L.m2.h-1 and reverse salt flux of 10.9 g.m2.h-1, when deionized wastewater and potassium chloride were used as the feed solution and the draw solution, respectively. In this manner, incorporating manganese oxide into the FO membrane may introduce its extraordinary possible application for the production of diluted fertilizer solution with balanced nutrients.

New bismuth oxyiodide/chitosan nanocomposite for ultrasonic waves expedited adsorptive removal of amoxicillin from aqueous medium: kinetic, isotherm and thermodynamic investigations.

Amoxicillin (AMX) is a widely used antibiotic, which induces harmful effects to nature via bioaccumulation and persistence in the environment if discharged untreated into water bodies. In the current study, a novel bionanocomposite, bismuth oxyiodide-chitosan (BiOI-Ch), was synthesized by a facile precipitation method and its amoxicillin (AMX) adsorption capacity in the presence of ultrasonic waves has been explored. Multiple batch experiments were performed to achieve the optimum operational parameters for maximum adsorption of AMX and the obtained results were as follows: pH 3, 80 mg g-1 AMX concentration, 1.7 g L-1 adsorbent dose, temperature 298 K and ultrasonication time 20 min. Composite removed approximately 90% AMX from the solution under optimized conditions, while the maximal adsorption capacity was determined to be 81.01 mg g-1. BiOI-Ch exhibited superior adsorption capacity as compared to pure BiOI (33.78 mg g-1). To understand the dynamics of reaction, several kinetic and isotherm models were also examined. The adsorption process obeyed pseudo-second-order kinetic model (R2 = 0.98) and was well fitted to Freundlich isotherm (R2 = 0.99). The addition of biowaste chitosan to non-toxic bismuth-based nanoparticles coupled with ultrasonication led to enhanced functional groups as well as surface area of the nanocomposite resulting in superior adsorption capacity, fast adsorption kinetics and improved mass transfer for the removal of AMX molecules. Thus, this study demonstrates the synergistic effect of ultrasonication in improved performance of novel BiOI-Ch for potential application in the elimination of persistent and detrimental pollutants from industrial effluent after necessary optimization for large-scale operation.

Fabrication and characterization of high-performance forward-osmosis membrane by introducing manganese oxide incited graphene quantum dots.

Forward osmosis (FO) is the futuristic membrane desalination technology as it transcends the disadvantages of other pressure-driven techniques. But, there still remain critical challenges like fabrication of highly permeable membrane with ideal structures maintaining high rejection rates that need to be addressed for implementation as a practical technology. In this work, novel thin-film composite (TFC) membranes were fabricated by means of incorporating manganese oxide (MnO2) incited graphene quantum dots (GQDs) nanocomposite into a cellulose acetate (CA) suspension followed by phase inversion (PI) for enhanced FO performance. The surface morphology and chemical structure of fabricated membranes were studied using various characterization techniques like XRD, FT-IR, SEM-EDS, Mapping, AFM, and TGA. The structural parameters, water flux, reverse salt flux and salt rejection was estimated on the basis of data obtained from four varying initial draw solution concentrations. At high nanocomposites stacking, the hydrophilicity of the casting blend increase, and subsequently, the PI exchange rate additionally increases, which brings about noticeable difference in the surface morphology. The membrane with 0.5 wt% nanocomposite exhibited superior FO separation performance with osmotic water flux of 18.89, 34.49, 41.76 and 42.34 in L.m-2.h-1 with variable concentrations of NaCl salt solution (0.25M, 0.5M, 1M, and 2M), respectively. Also, the porosity of the membrane was increased to 47.23% with 96.87% salt rejection. The results indicate that the hydrophilicity of the nanocomposite drives them to the interface among CA and water during PI process leading to solid hydrogen bonding to achieve high water permeability.

Design and development of a portable resistive sensor based on α-MnO2 /GQD nanocomposites for trace quantification of Pb(II) in water.

The occurrence of heavy metal ions in food chain is appearing to be a major problem for mankind. The traces of heavy metals, especially Pb(II) ions present in water bodies remains undetected, untreated, and it remains in the food cycle causing serious health hazards for human and livestock. The consumption of Pb(II) ions may lead to serious medical complications including multiple organ failure which can be fatal. The conventional methods of heavy metal detection are costly, time-consuming and require laboratory space. There is an immediate need to develop a cost-effective and portable sensing system which can easily be used by the common man without any technical knowhow. A portable resistive device with miniaturized electronics is developed with microfluidic well and α-MnO2 /GQD nanocomposites as a sensing material for the sensitive detection of Pb(II). α-MnO2 /GQD nanocomposites which can be easily integrated with the miniaturized electronics for real-time on-field applications. The proposed sensor exhibited a tremendous potential to be integrated with conventional water purification appliances (household and commercial) to give an indication of safety index for the drinking water. The developed portable sensor required low sample volume (200 µL) and was assessed within the Pb(II) concentration range of 0.001 nM to 1 uM. The Limit of Detection (LoD) and sensitivity was calculated to be 0.81 nM and 1.05 kΩ/nM/mm2 , and was validated with the commercial impedance analyser. The shelf-life of the portable sensor was found to be ∼45 days.

Microfluidic Affinity Sensor Based on a Molecularly Imprinted Polymer for Ultrasensitive Detection of Chlorpyrifos.

The persistent use of pesticides in the agriculture field remains a serious issue related to public health. In the present work, molecularly imprinted polymer thin films were developed using electropolymerization of pyrrole (py) onto gold microelectrodes followed by electrodeposition for the selective detection of chlorpyrifos (CPF). The molecularly imprinted polymer (MIP) was synthesized by the electrochemical deposition method, which allowed in-line transfer of MIP on gold microelectrodes without using any additional adhering agents. Various parameters such as pH, monomer ratio, scan rate, and deposition cycle were optimized for sensor fabrication. The sensor was characterized at every stage of fabrication using various spectroscopic, microscopic, and electrochemical techniques. The sensor requires only 2 µL of the analyte and its linear detection range was found to be 1 µM to 1 fM. The developed sensor's limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.93 and 2.82 fM, respectively, with a sensitivity of 3.98 (µA/(µM)/ mm2. The sensor's shelf life was tested for 70 days. The applicability of the sensor in detecting CPF in fruit and vegetable samples was also assessed out with recovery % between 91 and 97% (RSD < 5%). The developed sensor possesses a huge commercial potential for on-field monitoring of pesticides.

Engineering of luminescent graphene quantum dot-gold (GQD-Au) hybrid nanoparticles for functional applications.

Graphene quantum dots (GQDs) possess excellent optical and electrical properties that can be used in a wide variety of application. Synthesis of hybrid nanoparticles with GQDs have been known to improve the properties further. Therefore, in this method, graphene quantum dots -gold (GQD-Au) hybrid nanoparticles were synthesized using GQDs which reduces HAuCl4.3H2O to Au nanoparticles on its surface at room temperature. The GQDs with self-passivated layers were synthesized by microwave assisted hydrothermal method using glucose as a single precursor. The synthesis process does not involve the use of harmful chemicals. The whole synthesis process of GQD and GQD-Au hybrid nanoparticles takes only five minutes. The synthesized GQDs have been extracted using citrate in order to increase the stability of the hybrid nanoparticles for up to four weeks. The size of the synthesized GQD-Au hybrid nanoparticles is in the range of 5-100 nm and were found to be luminescent under UV-A illumination. The merit of the following method over other synthesis techniques include its rapidity, ease of preparation, and no requirement of elaborate synthesis procedures and/or harmful chemicals. The GQD-Au hybrid nanoparticles can be used in several applications such as luminescent coatings for glass and windowpanes for automobiles, etc. The reducing property of GQDs can further be utilized for the reduction of various metal salts (AgNO3) and organic dyes (methylene blue and methyl orange). . It presents a method/protocol-development of the luminescent GQD-Au hybrid particles of size ~ 5-100 nm. . The GQD-Au hybrid particles find potential applications in luminescent coating applications.

Ion beam modified TiO2 nanotubular bio-interface for electrochemical detection of L-tyrosine towards smart bandage application.

One of the common complications diagnosed in Diabetes Mellitus (DM) patients is Diabetic Foot Ulcers (DFUs). It is a condition wherein the deep tissues located in the lower limb undergo inflammation and infection due to neurological abnormalities (neuropathy) and various degrees of vascular diseases (angiopathy). The concentration of l-tyrosine (Tyr) rises abruptly in DFUs, and therefore may be used as an indicator for early monitoring of the patient's condition during the onset of diabetic foot disease. Herein, we report the electrochemical enzymatic detection of Tyr using low energy ion beam modified titania nanotube (TiNT) thin films with nitrogen (N+) and gold (Au-) ions. Electrochemical Impedance Spectroscopy (EIS) analysis was performed to investigate the levels of Tyr using ion beam modified TiNT thin film electrodes. The modified electrodes exhibited excellent sensor performances with Au-TiNT and N-TiNT within the Tyr concentration range of 100 fM -500 µM with limit of detection (LoD)1.76 nM and 1.25 nM respectively and response time ∼ 1 min. The results indicate that low energy ion beam modified TiNT/enzyme bio-electrodes can potentially be employed as a highly sensitive and portable sensor for real-time detection of l-tyrosine in wound fluids for the development of a smart bandage.

Rapid removal of lead(II) ions from water using iron oxide-tea waste nanocomposite - a kinetic study.

Lead (Pb) ions are a major concern to the environment and human health as they are contemplated cumulative poisons. In this study, facile synthesis of magnetic iron oxide-tea waste nanocomposite is reported for adsorptive removal of lead ions from aqueous solutions and easy magnetic separation of the adsorbent afterwards. The samples were characterised by scanning electron microscopy, Fourier transform-infrared spectroscopy, X-ray diffraction, and Braunner-Emmet-Teller nitrogen adsorption study. Adsorptive removal of Pb(II) ions from aqueous solution was followed by ultraviolet-visible (UV-Vis) spectrophotometry. About 95% Pb(II) ion removal is achieved with the magnetic tea waste within 10 min. A coefficient of regression R2 ≃ 0.99 and adsorption density of 18.83 mg g-1 was found when Pb(II) ions were removed from aqueous solution using magnetic tea waste. The removal of Pb(II) ions follows the pseudo-second-order rate kinetics. External mass transfer principally regulates the rate-limiting phenomena of adsorption of Pb(II) ions on iron oxide-tea waste surface. The results strongly imply that magnetic tea waste has promising potential as an economic and excellent adsorbent for the removal of Pb(II) from water.

Electro-deposited nano-webbed structures based on polyaniline/multi walled carbon nanotubes for enzymatic detection of organophosphates.

We report the development of an ultrasensitive electrochemical sensor using polyaniline (PANi) and carboxyl functionalized multi-walled carbon nanotubes (fMWCNT) for the detection of organophosphates (OPs) in real samples. The sensor was tested in the linear concentration range of 10 ng/L to 120 ng/L. The limit of detection (LoD) was found to be 8.8 ng/L with sensitivity 0.41 mA/ng/L/cm2 for chlorpyrifos (CPF); and 10.2 ng/L with sensitivity 0.58 mA/ng/L/cm2 for methyl parathion (MP). The vegetable samples (cucumber) were also tested. The average % recovery for CPF and MP were found to be 98.05% and 96.63% respectively. The developed sensor showed stability for a period of 30 days. The interference of the sensor was studied with heavy metals (cadmium (Cd), chromium (Cr), lead (Pb), arsenic (As)) which was found to be < 10%. The developed sensor will play a major role in real-time monitoring of food products, leading to food safety.

Few biomedical applications of carbon nanotubes.

Nanotubes of carbon are allotropic form of carbon material that rolled to form a cylindrical structure that may be singlewalled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs) depending upon the number of carbon layers. These carbon nanotubes have exhibited characteristics properties such as  electrical, optical, thermal and mechanical. Carbon nanotubes can be employed for immobilization matrix for biomolecules such as an enzyme, nucleic acid, etc. Enzymes can be immobilized onto carbon nanotubes via absorption or covalent bonding. Various enzymatic based biosensors are also developed for the detection of various analytes. Present chapter mainly emphasizes characteristics of carbon nanotubes, their preparation methods, purification and exploitation of CNTs as an immobilization matrix for theranostic applications.

Paper based point of care immunosensor for the impedimetric detection of cardiac troponin I biomarker.

Advancements in health care monitoring demand a rapid, accurate and reliable early diagnosis of "Heart Attack" (acute myocardial infarction) with an objective to develop a cost-effective, rapid and label-free point of care diagnostic test kit for the detection of cardiac troponin I (cTnI) on paper-based multi-frequency impedimetric transducers. Paper based sensing platforms were developed by integrating carboxyl group functionalized multi-walled carbon nanotubes (MWCNT) with antibodies of cardiac troponin I (anti-cTnI) biomarker and was characterized using Electrochemical Impedance Spectroscopy (EIS). Various concentrations of cTnI with anti cTnI were studied as a function of impedance change. The suitability of the proposed immunosensor is demonstrated by spiking cTnI in blood serum samples. The limit of detection (LoD) and sensitivity of the proposed sensor was determined to be 0.05 ng/mL and 1.85 mΩ/ng/mL respectively, with a response time of ~1 min. The shelf life of the fabricated sensor was nearly 30 days. The rapid response, very low detection limit, and cost effectiveness offer a portable platform to detect cTnI in blood serum samples. The proposed immunosensor, therefore, offers an affordable healthcare diagnostic platform in resource limited areas.

Development of MoSe2 Nano-Urchins as a Sensing Platform for a Selective Bio-Capturing of Escherichia. coli Shiga Toxin DNA.

The present study was aimed to develop "fluorine doped" tin oxide glass electrode with a MoSe2 nano-urchin based electrochemical biosensor for detection of Escherichia. coli Shiga toxin DNA. The study comprises two conductive electrodes, and the working electrodes were drop deposited using MoSe2 nano-urchin, and DNA sequences specific to Shiga toxin Escherichia. coli. Morphological characterizations were performed using Fourier transforms infrared spectrophotometer; X-ray diffraction technique and scanning electron microscopy. All measurements were done using methylene blue as an electrochemical indicator. The proposed electrochemical geno-sensor showed good linear detection range of 1 fM⁻100 µM with a low detection limit of 1 fM where the current response increased linearly with Escherichia. coli Shiga toxin dsDNA concentration with R2 = 0.99. Additionally, the real sample was spiked with the dsDNA that shows insignificant interference. The results revealed that the developed sensing platform significantly improved the sensitivity and can provide a promising platform for effective detection of biomolecules using minute samples due to its stability and sensitivity.

Comparative analysis of single-walled and multi-walled carbon nanotubes for electrochemical sensing of glucose on gold printed circuit boards.

In the present work, a comparative study was performed between single-walled carbon nanotubes and multi-walled carbon nanotubes coated gold printed circuit board electrodes for glucose detection. Various characterization techniques were demonstrated in order to compare the modified electrodes viz. cyclic voltammetry, electrochemical impedance spectroscopy and chrono-amperometry. Results revealed that single-walled carbon nanotubes outperformed multi-walled carbon nanotubes and proved to be a better sensing interface for glucose detection. The single-walled carbon nanotubes coated gold printed circuit board electrodes showed a wide linear sensing range (1 mM to 100 mM) with detection limit of 0.1 mM with response time of 5 s while multi-walled carbon nanotubes coated printed circuit board gold electrodes showed linear sensing range (1 mM to 100 mM) with detection limit of 0.1 mM with response time of 5 s. This work provided low cost sensors with enhanced sensitivity, fast response time and reliable results for glucose detection which increased the affordability of such tests in remote areas. In addition, the comparative results confirmed that single-walled carbon nanotubes modified electrodes can be exploited for better amplification signal as compared to multi-walled carbon nanotubes.

A new tactics for the detection of S. aureus via paper based geno-interface incorporated with graphene nano dots and zeolites.

Staphylococcus aureus (S. aureus) is a pathogenic bacteria which causes infectious diseases and food poisoning. Current diagnostic methods for infectious disease require sophisticated instruments, long analysis time and expensive reagents which restrict their application in resource-limited settings. Electrochemical paper based analytical device (EPAD) was developed by integrating graphene nano dots (GNDs) and zeolite (Zeo) using specific DNA probe. The ssDNA/GNDs-Zeo modified paper based analytical device (PAD) was characterized using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The genosensor was optimized at pH7.4 and incubation temperature of 30°C. A linear current response with respect to target DNA concentrations was obtained. The limit of detection (LOD) of the proposed sensor was found out to be 0.1nM. The specificity was confirmed by introducing non-complimentary target DNA to ssDNA/GNDs-Zeo modified PAD. The suitability of the proposed EPAD genosensor was demonstrated with fruit juice samples mixed with S. aureus. The proposed EPAD genosensor is a low cost, highly specific, easy to fabricate diagnostic device for detection of S. aureus bacteria which requires very low sample volume and minimum analysis time of 10s.