Optical design and fabrication of zinc selenide microlens array with extended depth of focus for biomedical imaging
Neha Khatri, Sonam Berwal, K Manjunath, Bharpoor Singh
Optical coherence tomography is a well-known technique for the optical imaging biological tissues. However, the depth scanning range of high-resolution optical coherence tomography is restricted by its depth of focus. In this study, a Zinc Selenide (ZnSe) Microlens Array (MLA) is employed to overcome the depth-of-focus limitation of optical coherence tomography. The ZnSe material with a low Abbe number and high chromatic dispersion extends the depth of focus with transverse resolution. The ZnSe MLA focused the incident light (from visible to near-infrared (NIR) region) on multiple focal planes with the uniform distribution of light over a biological tissue. The MLA is designed using Zemax OpticStudio software and fabricated via a single-point diamond-turning based on Slow Tool Servo (STS) configuration. STS machining has the unique advantage of offering larger degrees of freedom with no additional baggage, thereby reducing the setup time. The experimental results show the effectiveness of the STS machining process in fabricating ZnSe MLA with desired accuracies. The characterization of fabricated MLA using Coherence Correlation Interferometry (CCI) depicts uniform lenslets with no structural and positional distortion, with a total error of 32 nm within the tolerance limit.
Green synthesis of gold nanoaprticles using black tea extract and their effect on the morphology and their antibacterial activity
B. Srividhya, R. Subramanian, V. Raj
Herbal extract stabilized green synthesis of nanoparticles is an alternative reducing agent for chemical synthesis. In this manuscript, green synthesis of gold nanoparticles (AuNPs) has been performed using aqueous extract of black tea. The effect of tea extract concentration on the morphology of the particles was studied. Formation, functional groups, crystalline phase, and morphology changes of the nanoparticles were characterized by UV-Vis spectrophotometer, Fourier transforms spectrometer, an X-ray diffraction pattern (XRD), scanning electron microscope (SEM), energy dispersive diffraction (EDS), and transmission electron microscopy (TEM) coupled with selected area diffraction. Antibacterial activity AuNPs were studied against bacteria. It was found that as the concentration of the tea extract increased, the shape of the particles changed and finally became spherical at high concentrations. The results of this research reveal the antibacterial activity of AuNPs.
Formulation and Evaluation of Mucoadhesive Buccal tablets using Nimodipine Solid Lipid Nanoparticles
Remya Prabhavathi Neelakandan, Divya R, Damodharan N
This study aimed to create and describe mucoadhesive nimodipine solid lipid nanoparticles as buccal tablets by altering the amounts of three polymers: Carbopol 934, Hydroxypropyl methylcellulose and Hydroxyethyl cellulose. The Nimodipine-loaded solid lipid nanoparticles (SLN) were formulated by high shear homogenization and ultrasonication process using palmitic and stearic acid as the lipid matrix and Tween-80 as the surfactant. The swelling properties of all formulations were investigated, and it was discovered that all formulations have a good swelling index at 6 hours. The surface pH of each batch varied between 5.6 and 6.1. The mucoadhesive strengths (15.3-29.5 g) varied with polymer concentrations, particularly Carbopol 934. All batches had considerably different dissolution profiles, ranging from a maximum release of 89.08% (at 8h in batch NT3) to a minimum release of 80.32% (at 8h in batch NT2). SLN formulations had the best results in both Entrapment efficiency and In-vitro drug release, showing that SLN may be a promising delivery strategy for improving Nimodipine release.
María Fernanda Cárdenas-Alcaide, Reyna Berenice González-González, Angel M. Villalba-Rodríguez, Itzel Y. López-Pacheco, Roberto Parra-Saldívar, Hafiz M.N. Iqbal The article was first published on Mar 8, 2023
Nanofabrication and characterization of green-emitting N-doped carbon dots derived from pulp-free lemon juice extract
María Fernanda Cárdenas-Alcaide, Reyna Berenice González-González, Angel M. Villalba-Rodríguez, Itzel Y. López-Pacheco, Roberto Parra-Saldívar, Hafiz M.N. Iqbal
In this work, highly fluorescent green-emitting N-doped carbon dots (N-CDs) were derived from pulp-free lemon juice extract, as a green precursor, through a one-pot carbonization at 180 oC for 3 to 5 h. The newly fabricated N-CDs were thoroughly characterized using different imaging and analytical techniques, including Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), Fluorescence spectroscopy, X-ray diffraction analysis (XRD), and Ultraviolet-visible (UV-Vis) spectroscopy. The preliminary evaluation showed that N-CDs synthesized at 180 ºC for 3 and 5 hours emit bright green light under UV or blue light irradiation with a quantum yield of 16.33% and 21.80%, respectively. The fluorescence spectroscopic profiles revealed that as-developed N-CDs exhibit excitation-independent photoluminescence (PL) emission at 365 nm. FTIR profile reveals the functional group entities with evident peaks in 3190 cm−1, 1660 cm−1, 1580 cm−1, 1405 cm−1, 1365 cm−1, 1190 cm−1, and 1060 cm−1 regions, among others that correspond to the presence of N-H, C-H, C=O and C=N, C=C, C-H, COOH, C-O-C, and C-O. SEM unveils uniform and well-crystalline morphology of N-CDs.
Degradation of malachite green dye by capping polyvinylpyrrolidone and Azadirachta indica in hematite phase of Ni doped Fe2O3 nanoparticles via co-precipitation method
Naveen Thakur, Pankaj Kumar, Ashwani Tapwal, Kamal Jeet
In the present research, a chemical co-precipitation approach has been used to approach the synthesis, characterization, and photocatalytic applicability of Ni-doped α-Fe2O3 (hematite) nanoparticles. Biosynthesized iron oxide nanoparticles (IONPs) were successfully synthesized using a non-toxic leaf extract of the Azadirachta indica (AI) plant (neem) as a reducing and stabilizing agent. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Raman spectroscopy, FT-IR spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, and vibrating sample magnetometer (VSM) have all been used to examine the synthesized materials. All of the produced NPs contain only the nanocrystalline hematite phase, according to XRD measurements. The morphology studies of the Ni-doping hematite nanoparticles, as demonstrated by TEM and SEM. The phase purity and phonon modes of the prepared nanoparticles are confirmed by Raman spectroscopy. The UV-Vis absorption tests show also that value of the band gap increases together with the reduction in particle size, going from 2.26 eV for chemical α-Fe2O3 to 2.5 eV for green Ni-doped α-Fe2O3 nanoparticles. Additionally, it was clear from the magnetic characteristics that all of the samples behaved ferromagnetically at ambient temperatures. On the other side, malachite green (MG) dye was used as a surrogate industrial wastewater dye in order to study the photocatalytic efficiency of Ni-doped α-Fe2O3 particles. The pure/green Ni-doped α-Fe2O3 NPs showed that after 70 minutes of exposure, 92% of the MG had become discolored.
The primary global source of water pollution is textile dyes. Highly stable organic dyes are produced by these industries that are released untreated into nearby ponds, lakes and rivers. This paper is devoted to synthesis of nickle doped anatase phase of TiO2 nanoparticles (Ni-ATD NPs) by encapsulating plant Tinospora cordifolia (TC) through microwave assisted method for degradation of malachite green (MG) dye. The synthesized NPs were calcinated at 400 oC temperature to achieve the anatase phase. The synthesized Ni-ATD NPs were analysed with different characterization methods. X-ray diffraction (XRD) and Raman analysis confirmed the crystalline nature for Ni-ATD NPs with a tetragonal structure having crystallite size of 11 nm. Scanning electron microscope (SEM) determined the spherical surface morphology for synthesized NPs. The absorption peaks of Ni-ATD NPs were originated from 360 to 370 nm from UV-Visible spectroscopy in which the bandgap was found to be 3.45 eV. The photocatalytic activity for MG dye was evaluated under ultra-violet (UV) light using Ni-ATD NPs for 90 minutes which exhibited the degradation up to 100 %.
Enhanced Photocatalytic Applications of Chitosan Encapsulated Silver Sulphide Quantum Dots
Ambalika Sharma, Rahul Sharma, Asha Kumari
This study explores the synthesis, properties, and applications of chitosan-encapsulated silver sulphide (Ag2S) quantum dots (QDs) for biological applications. The investigation focuses on the fluctuations in the physico-chemical characteristics of chitosan Ag2S QDs, which can be carefully studied due to their environmental activity. X-ray diffraction (XRD) measurements reveal that chitosan-coated Ag2S QDs exhibit higher-intensity peaks. The XRD analysis reports a range of crystallite sizes, with a minimum size of 8 nm and a maximum size of 12 nm. Fourier-transform infrared (FTIR) spectroscopy confirms the presence of chitosan through the detection of functional group peaks. High-resolution transmission electron microscopy (HRTEM) studies indicate that the size of the artificial quantum dots is 6 nm. Energy-dispersive X-ray spectroscopy (EDX) verifies the composition of chitosan-encapsulated Ag2S QDs. Moreover, the chitosan Ag2S quantum dots demonstrate exceptional photocatalytic activity, as evidenced by the degradation of 92% of methylene blue dye within one hour. This research provides valuable insights into the synthesis, properties, and potential applications of chitosan-encapsulated Ag2S quantum dots in diverse fields.
Rapid tooling using additive manufacturing, or 3D printing, is an emerging manufacturing technology that has the potential to revolutionize the production of complex parts using only a computer and a design program. Lightweight structures with excellent dimensional precision and lower cost for customizable geometries are possible with these printed parts. In recent years, inherent constraints of polymers, metals, and ceramics have pushed researchers toward superior alternative composite materials to boost mechanical and other critical features; current 3D printing research follows this route from neat to composite materials. The characteristics, performance, and future uses of composite materials produced using additive manufacturing methods are discussed in this review. In addition, to discuss the state of the art in additive manufacturing, this article also fabricated many technologies, including robotics, machine learning, organ-on-a-chip, and 4D bioprinting.
The contemporary era's top environmental problems include the lack of energy, recycling of waste resources, and water pollution. Due to the speedy growth of modern industrialization, the utilization of non-renewable sources has increased rapidly, which has caused many serious environmental and energy issues. In photocatalysis, as a proficient candidate, g-C3N4 (metal-free polymeric photocatalyst) has gained much attention due to its auspicious properties and excellent photocatalytic performance. But, regrettably, the quick recombination of photoinduced charge carriers, feeble redox ability, and inadequate visible light absorption are some major drawbacks of g-C3N4 that hamper its photocatalytic ability. Henceforth, these significant limitations can be solved by incorporating modification strategies. Among all modification techniques, the amalgamation of g-C3N4 with two or more photocatalytic semiconducting materials via heterojunction formation is more advantageous. In this review, we have discussed various modification strategies, including conventional, Z-scheme and S-scheme heterojunctions. S-scheme heterojunction is consideredan efficient and profitable charge transferal pathway due to the excellent departure and transferal of photoexcited charge carriers with outstanding redox ability. Consequently, the current review is focused on various photocatalytic applications of S-scheme-based g-C3N4 photocatalysts in pollutant degradation, H2 production, and CO2 reduction.
A review on emerging micro and nanoplastic pollutants, heavy metals and their remediation techniques
Gargi Mandal, Sumit Mishra
Plastics have become one of the most concerning pollutants today. They are non-biodegradable and potentially carcinogenic and lead to the generation of microplastics categorised as an emerging pollutant. Microplastics are plastic particles smaller than 5 microns in size. They are reported in various parts of the biosphere including human blood and tissues of various organs. Industrial and domestic effluents are two major contributing sources of microplastics in the ecosystem. A large volume of microplastics escape from the filtration processes of wastewater treatment plants (WWTP). This review studies the various removal methods for these pollutants in large-scale as well as lab-scale models and the present state of art facilities available to deal with it.
The research of energy-storage systems has been encouraged in the last ten years by the rapid development of portable electronic gadgets. Hybrid-ion capacitors are a novel kind of capacitor-battery hybrid energy storage device that has earned a lot of interest because of their high power density while maintaining energy density and a long lifecycle. Mostly, lithium-based energy storage technology is now being studied for use in electric grid storage. But the price increment and intermittent availability of lithium reserves make lithium-based commercialization unstable. Therefore, sodium-based technologies have been proposed as potential substitutes for lithium-based technologies. Sodium-ion capacitors (SICs) are acknowledged as potential innovative energy storage technologies which have lower standard electrode potentials and lower costs than lithium-ion capacitors. However, the large radius of the sodium ion also contributes to unfavorable reaction kinetics, low energy density, and brief lifespan of SICs. Recently, transition metal oxide (TMO)-based candidates have been considered potential due to the large theoretical capacity, environmental friendliness, and low cost for SICs. This brief study summarizes current advancements in research of TMOs and sodium-based TMOs as electrode candidates for SIC applications. Also, we have covered in detail the state of the exploration and upcoming prospects of TMOs for SICs.
CO2 electro/photocatalytic reduction using nanostructured ZnO and silicon-based materials: A short review
Andrés Galdámez-Martínez, Ateet Dutt
Reducing CO2 net emissions is one of the most pressing goals in tackling the current global warming emergency. Therefore, the development of carbon recycling strategies has resulted in the application of heterogeneous catalysts toward the electro/photocatalysis reduction of CO2 into hydrocarbons with potential reusability. Their morphology is among the properties that affect the performance and selectivity of catalysts towards this reaction. Nanostructuring methods offer popular strategies for catalytic applications since they allow an increase in the area/volume ratio and versatile control over surface physicochemical properties. In this review, we summarize studies that report the use of versatile synthesis techniques for obtaining nanostructured metallic and semiconductor materials with application in the electro/photocatalytic reduction of CO2. Enhancing mechanisms to the catalytic CO2 reduction yield, such as improved charge carrier separation efficiency, defect engineering, active site concentration, and localized plasmonic behavior, are described in conjunction with the control over the morphologies of the nanostructured platforms. Special attention is given to ZnO and silicon-based matrices as candidates for developing abundant and non-toxic catalytic materials. Therefore, this work represents a guide to the efforts made to design electro/photocatalytic systems that can contribute significantly to this field.
Synthesis and Biomedical Applications of Polymer-Functionalized Magnetic Nanoparticles
Gamze Dik, Ahmet Ulu, Burhan Ateş
Magnetic nanoparticles (MNPs) are receiving increasing attention from individual scientists and research companies as promising materials for biomedical applications. MNPs can be synthesized by many different methods. Before proceeding to the synthesis process, the cost of using it and the practicality of the synthesis conditions are well investigated. Especially in their use in the biomedical field, features such as not containing toxic substances, high biocompatibility, and low particle size are desired. However, the use of magnetic nanoparticles in biomedical applications is limited due to various difficulties such as particle agglomeration and oxidation of magnetic cores of MNPs. To overcome these challenges, MNPs can be coated with various natural and synthetic polymers to alter their morphological structure, magnetic character, biocompatibility, and especially surface functional groups. Therefore, this review focuses on the synthesis of MNPs by different methods and the effects of these synthesis methods on magnetic properties and size, their modifications with natural and synthetic polymers, and the use of these polymer-coated MNPs in biomedical fields such as targeted drug release, enzyme immobilization, biosensors, tissue engineering, magnetic imaging, and hyperthermia. The review article also provides examples of advanced biomedical applications of polymer-coated MNPs and perspectives for future research to promote polymer-coated MNPs. To this end, we aim to highlight knowledge gaps that can guide future research to improve the performance of MNPs for different applications.
A perspective on nanocomposite coatings for advanced functional applications
Jaya Verma, Saurav Goel
Functional coatings provide durability to the bulk material and add other value-added properties which enhance the surface's mechanical, electrical, optical, and many other properties. The functional response of these coatings stems from the ambiance, which can be made to sense in response to a sharp change in the temperature, pH, moisture, active ions, or mechanical stresses. Recently, many efforts have been made to impart multi-functionality within a single coating, i.e., to achieve hydrophobicity and antifouling characteristics, which can be achieved by combining an appropriate coating material with a geometric nanopattern. Such coatings are poised to shape the future of the transport, healthcare, and energy sectors, including marine, aeronautics, automobile, petrochemical, biomedical, electrical and electronic industries. This perspective sheds light on the design specifications and requirements to fabricate functional coatings and critically discusses the fabrication methods, working principles, and case studies to survey various applications with a particular focus on anti-corrosion and self-cleaning applications.
Nanofabrication (2299-680X) is the first journal to highlight the importance of the interface of science and engineering in Nanofabrication and its role in this multidisciplinary and collaborative research area. Nanofab is indexed by Emerging Science Citation Index. Read more...
Prof. Vijay Kumar Thakur, Biorefining & Advanced Materials Research Centre, SRUC, Edinburgh, UK. Editorial Team...