Santanu Dhara

Bio: Santanu Dhara is an academic researcher from Indian Institute of Technology Kharagpur. The author has contributed to research in topics: Self-healing hydrogels & Materials science. The author has an hindex of 35, co-authored 216 publications receiving 4350 citations. Previous affiliations of Santanu Dhara include University of Birmingham & Indira Gandhi Centre for Atomic Research.

A Simple Direct Casting Route to Ceramic Foams

Abstract: A simple direct foaming and casting process using ovalbumin-based aqueous slurries for fabricating ceramic and metal foams is demonstrated. Foaming of aqueous ceramic slurries and the foam microstructure were seen to be a strong function of slurry rheology. Setting of foams with ceramic solids loading above 20 vol% was achieved by addition of acid, which also prevented binder migration. Acid addition resulted in excessive shrinkage, causing cracking of foams with ceramic loading below 20 vol%. Addition of sucrose to the slurries suppressed shrinkage leading to defect-free foams with porosity exceeding 95%. Overall porosity and foam microstructure could be controlled through ceramic solids loading, ovalbumin–water ratio, foaming time and sucrose amount, and sintering temperature. The ceramic foams fabricated by the process were strong enough to be green machined to different shapes.

Stimulus-Responsive, Biodegradable, Biocompatible, Covalently Cross-Linked Hydrogel Based on Dextrin and Poly(N-isopropylacrylamide) for in Vitro/in Vivo Controlled Drug Release

Abstract: A novel stimulus-sensitive covalently cross-linked hydrogel derived from dextrin, N-isopropylacrylamide, and N,N′-methylene bis(acrylamide) (c-Dxt/pNIPAm), has been synthesized via Michael type addition reaction for controlled drug release application. The chemical structure of c-Dxt/pNIPAm has been confirmed through Fourier transform infrared (FTIR) spectroscopy and 1H and 13C NMR spectral analyses. The surface morphology of the hydrogel has been studied by field emission scanning electron microscopic (FE-SEM) and environmental scanning electron microscopic (E-SEM) analyses. The stimulus responsiveness of the hydrogel was studied through equilibrium swelling in various pH media at 25 and 37 °C. Rheological study was performed to measure the gel strength and gelation time. Noncytotoxicity of c-Dxt/pNIPAm hydrogel has been studied using human mesenchymal stem cells (hMSCs). The biodegradability of c-Dxt/pNIPAm was confirmed using hen egg lysozyme. The in vitro and in vivo release studies of ornidazole and ...

Carbon nanodots from date molasses: new nanolights for the in vitro scavenging of reactive oxygen species.

Abstract: Most of the nanoimaging tools like quantum dots and metallic nanoparticles are shown to have different levels of cytotoxicity via various mechanisms. However carbon nanodots (CNDs) are a new group of ultra small nano structures (average 4–6 nm) which is potential candidate of next generation optical imaging. Being carbonaceous in origin, CNDs possess excellent luminescence and photostability with significantly less cytotoxicity. In present study, we have synthesized carbon nano-dots from date molasses by microwave irradiation at ∼pH 11. The synthesized carbon nanodots were characterized using UV-Vis spectroscopy, fluorescence spectroscopy, TEM, XRD analysis, FTIR study and Zeta potential measurement. The average sizes of the dots were found to be 5–7 nm. A clear band emission was visible around 480 nm when an excitation beam of 415 nm was incident. For biological applicability, MTT assay and hemocompatibility studies were performed. The results exhibited the material to be highly cytocompatible within the application limit. Upon immediate exposure to CNDs, no significant changes to cellular surface morphology were observed via AFM imaging. Significant hemolysis or blood cell aggregation was not observed after incubation of CNDs with blood. After labelling with CNDs, MG-63 cells were found to be unbleached up to several hours even on exposure to light. We are reporting first time in this study the free radical scavenging property of CNDs in ex vivo and in vitro models. Antioxidant activity was measured ex vivo via potassium permanganate assay and DPPH assay. In vitro superoxide inhibition activity was measured both by spectroscopy and under microscope by NBT reduction assay. Hydroxyl free radical inhibition activity was measured via DCFH-DA Assay. The results were comparable with scavenging activity of standard antioxidant molecules (BHT and L-ascorbic acid). A novel assay for quantitative analysis of cellular oxidative stress was also proposed. Therefore, this material could be useful for long-term live cell imaging and cell tracking in a scaffold with minimal cytotoxicity and oxidative stress.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Electrospinning and Electrospun Nanofibers: Methods, Materials, and Applications

Abstract: Electrospinning is a versatile and viable technique for generating ultrathin fibers. Remarkable progress has been made with regard to the development of electrospinning methods and engineering of electrospun nanofibers to suit or enable various applications. We aim to provide a comprehensive overview of electrospinning, including the principle, methods, materials, and applications. We begin with a brief introduction to the early history of electrospinning, followed by discussion of its principle and typical apparatus. We then discuss its renaissance over the past two decades as a powerful technology for the production of nanofibers with diversified compositions, structures, and properties. Afterward, we discuss the applications of electrospun nanofibers, including their use as "smart" mats, filtration membranes, catalytic supports, energy harvesting/conversion/storage components, and photonic and electronic devices, as well as biomedical scaffolds. We highlight the most relevant and recent advances related to the applications of electrospun nanofibers by focusing on the most representative examples. We also offer perspectives on the challenges, opportunities, and new directions for future development. At the end, we discuss approaches to the scale-up production of electrospun nanofibers and briefly discuss various types of commercial products based on electrospun nanofibers that have found widespread use in our everyday life.

Processing Routes to Macroporous Ceramics: A Review

Abstract: Macroporous ceramics with pore sizes from 400 nm to 4 mm and porosity within the range 20%–97% have been produced for a number of well-established and emerging applications, such as molten metal filtration, catalysis, refractory insulation, and hot gas filtration. These applications take advantage of the unique properties achieved through the incorporation of macropores into solid ceramics. In this article, we review the main processing routes that can be used for the fabrication of macroporous ceramics with tailored microstructure and chemical composition. Emphasis is given to versatile and simple approaches that allow one to control the microstructural features that ultimately determine the properties of the macroporous material. Replica, sacrificial template, and direct foaming techniques are described and compared in terms of microstructures and mechanical properties that can be achieved. Finally, directions to future investigations on the processing of macroporous ceramics are proposed.

25th Anniversary Article: Rational Design and Applications of Hydrogels in Regenerative Medicine

Abstract: Hydrogels are hydrophilic polymer-based materials with high water content and physical characteristics that resemble the native extracellular matrix. Because of their remarkable properties, hydrogel systems are used for a wide range of biomedical applications, such as three-dimensional (3D) matrices for tissue engineering, drug-delivery vehicles, composite biomaterials, and as injectable fillers in minimally invasive surgeries. In addition, the rational design of hydrogels with controlled physical and biological properties can be used to modulate cellular functionality and tissue morphogenesis. Here, the development of advanced hydrogels with tunable physiochemical properties is highlighted, with particular emphasis on elastomeric, light-sensitive, composite, and shape-memory hydrogels. Emerging technologies developed over the past decade to control hydrogel architecture are also discussed and a number of potential applications and challenges in the utilization of hydrogels in regenerative medicine are reviewed. It is anticipated that the continued development of sophisticated hydrogels will result in clinical applications that will improve patient care and quality of life.

Advanced Organic Chemistry

Abstract: Organic Chemistry By Dr. I. L. Finar. Vol. 2: Stereochemistry and the Chemistry of Natural Products. Pp. xi + 733. (London and New York: Longmans, Green and Co., Ltd., 1956.) 40s. net.