Browsing by Author "Mohan Balakrishnan, R.M."

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A perspective of advanced biosensors for environmental monitoring
(Elsevier, 2019) Mohan Balakrishnan, R.M.; Uddandarao, U.; Raval, K.; Raval, R.
Biosensor technology has developed in leaps and bounds due to multidisciplinary approach between biotechnology and nanotechnology. This synergy provided much needed characteristic features, such as sensitivity and selectivity to the biosensor technology. Biosensors are venerated as superior entities for electrochemical, optical, and calorimetric-based sensing because of their exceptional size properties. They are the potential tools, which exhibited the feasibility and potential in detecting various biological, physical, chemical, radiological contaminants in water. This book chapter outlines the overview of various types of sensors, especially on chalcogen-based semiconductor nanoparticles. In this scenario, green route nanoparticles which employ PbSe quantum dots synthesis via marine Aspergillus terreus and ZnS/PbS nanoparticles via an endophytic fungus Aspergillus flavus are focused in this chapter. The book chapter also discusses about highly selective biogenic nanosensors which play a significant role in improving the capacity of biosensors due to their size tuneable quantum confinement effects. Potential applications of these biosensors for environmental monitoring are discussed. © 2019 Elsevier Inc. All rights reserved.
Adsorption of ibuprofen using cysteine-modified silane-coated magnetic nanomaterial
(Springer, 2019) Kollarahithlu, S.C.; Mohan Balakrishnan, R.M.
Industrialization and growth of the pharmaceutical companies have been a boon to the mankind in our day to day life in myriad ways. However, due to the uninhibited release of these active pharmaceutical compounds into the water systems has caused detrimental effects to the genetic pool. In this study, l-cysteine-modified 3-glycidyloxypropyltrimethoxysilane-coated magnetic nanomaterial showed a maximum removal of the efficiency of 82.90% for the nanomaterial dosage of 30 mg at an initial concentration of 50 mg L?1 at pH 6.0. Further, the nanomaterial showed reusability efficiency up to 80% for three cycles. The adsorption kinetics follow the pseudo-second-order reaction and the adsorption isotherm model best fits the Langmuir isotherm proving the adsorption process to be a monolayer sorption on a monolayer surface. This magnetic nanomaterial could serve as a promising tool for the removal of pharmaceutical compounds from aqueous solutions. [Figure not available: see fulltext.]. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature.
Adsorption of pharmaceuticals pollutants, Ibuprofen, Acetaminophen, and Streptomycin from the aqueous phase using amine functionalized superparamagnetic silica nanocomposite
(Elsevier Ltd, 2021) Chandrashekar Kollarahithlu, S.; Mohan Balakrishnan, R.M.
Pharmaceuticals are one of the emerging pollutants that pose a severe threat to the aquatic habitats, which in turn affects other species in the biosphere. The superparamagnetic based silica nanocomposites modified with aminosilane were characterized for their physicochemical properties and also the purity of the nanocomposite obtained was determined. The adsorptive properties of the nanocomposites were investigated for the removal of pharmaceutical pollutants such as Ibuprofen, Acetaminophen, and Streptomycin from aqueous solutions. The adsorption process of pharmaceuticals was found to reach equilibrium within the first 15 min reporting high removal efficiency of up to 97% for Ibuprofen (IBF) followed by (94%) acetaminophen (ACE) and (70%) streptomycin (STR) for a concentration of 12 mg L?1. The adsorption process was found to follow the pseudo-second-order kinetics and fits well with the Langmuir isotherm model, confirming the adsorption on to the homogenous surface of the nanocomposite. The amine functional groups formed on the nickel ferrite nanocomposites by coating aminopropyltrimethoxysilane (APTS) were observed to aid the adsorption process. The adsorption capacity of the nanocomposites varies for IBF, ACE, and STR as 59, 58, and 49 mg g?1 at pH 7.0, 6.0, and 5.0, respectively. The amine coated magnetic nanocomposite also showed excellent regeneration capacity for up to four cycles and can be a promising adsorbent, especially for removing of pharmaceutical pollutants from aqueous streams. © 2021 Elsevier Ltd
Adsorption of selective fluoroquinolones by cysteine modified silane magnetic nanocomposite from the aqueous phase
(Institute for Ionics, 2023) Senathiraja, T.; Lolla, S.A.; Singh, Y.; Kollarahithlu, S.C.; Mohan Balakrishnan, R.M.
Elevated levels of pharmaceutical pollutants in the aquatic environment have caused detrimental effects on water quality and biodiversity. Nanomaterials are among the most promising technologies to detect, adsorb, and remove these pollutants from the aqueous systems. The current work explores the applicability of nickel ferrite nanocomposite functionalized with L-cysteine attached 3-glycidyloxypropyltrimethoxysilane to remove a selective class of antibiotics known as fluoroquinolones (Lomefloxacin, Ciprofloxacin, and Norfloxacin). 20 mg of this nanocomposite achieve maximum removal efficiencies of 61%, 67%, and 75% for 40 mg L−1 of lomefloxacin, norfloxacin, and ciprofloxacin, respectively. The nanocomposites also show good regeneration capacity with negligible reduction in the efficiencies up to three cycles. Furthermore, adsorption isotherms such as Langmuir and Freundlich isotherms were used to characterize the removal of fluoroquinolones from the aqueous phase by the nanocomposites. The results show that the adsorption process was in good agreement with the Langmuir isotherm, thus confirming its monolayer sorption process and also reveals that adsorption kinetics follows a pseudo-second-order model. The maximum adsorption capacity of functionalized nickel ferrite nanocomposites are 122 mg g−1, 135 mg g−1, and 150 mg g−1 for lomefloxacin, norfloxacin, and ciprofloxacin, respectively. Overall, all the results obtained indicate that the nickel ferrite nanocomposite functionalized with L-cysteine attached 3-glycidyloxypropyltrimethoxysilane is an effective adsorbent to remove fluoroquinolones from the aqueous systems and could be potentially incorporated in water treatment processes under well-defined parameters. © 2022, The Author(s) under exclusive licence to Iranian Society of Environmentalists (IRSEN) and Science and Research Branch, Islamic Azad University.
Adsorptive removal of trivalent and pentavalent arsenic from aqueous solutions using iron and copper impregnated melanin extracted from the marine bacterium Pseudomonas stutzeri
(Elsevier Ltd, 2020) Manirethan, V.; Raval, K.; Mohan Balakrishnan, R.M.
The metalloid arsenic is one of the most conspicuous groundwater contaminants in the Indian subcontinent and its removal from aqueous medium is the main focus of this study. The study aims at functionalising melanin using iron and copper for the efficient removal of arsenic and rendering water fit for consumption. Melanin obtained from the marine bacteria Pseudomonas stutzeri was functionalised by iron impregnation (Fe-melanin) and copper impregnation (Cu-melanin). Morphological studies using FESEM portrayed the impregnated iron and copper granules on the surface of melanin, while XRD analysis confirmed the presence of Fe2O3 and CuO on melanin. Adsorption studies on As (V) and As (III) were conducted using Fe-melanin and Cu-melanin for different operating variables like pH, temperature and contact time. More than 99% per cent of As (III) and As (V) from water was removed at a pH range between 4 and 6 within 50 min in the case of Fe-melanin and 80 min for Cu-melanin. Adsorption equilibrium studies showed better fit with Langmuir adsorption isotherm and had good agreement with Redlich-Peterson's three-parameter model. The maximum adsorption capacities of Fe-melanin and Cu-melanin obtained from Langmuir adsorption model are 50.12 and 20.39 mg/g, respectively, for As (V) and similarly 39.98 and 19.52 mg/g, respectively, for As (III). Arsenic-binding to the functionalised melanin was confirmed using FT-IR and the XPS analysis. Reuse of the adsorbent was effectively done by desorbing the iron and copper together with the bound As (III) and As (V) and further re-impregnation of iron and copper in melanin. Re-functionalised melanin showed 99% adsorption efficiency up to four cycles of adsorption/desorption. A novel iron and copper impregnated melanin was synthesized to remove As (III) and As (V) from groundwater and the adsorption process was optimized. © 2019 Elsevier Ltd
Amino acid functionalized metal oxide nanocomposite for the removal of fluoroquinolones
(Elsevier Ltd, 2023) Ilango, I.; Mohan Balakrishnan, R.M.
Antibiotic consumption has increased globally, and its discharge into water bodies at concentrations ranging from a few ng/L to mg/L has a detrimental effect on the ecosystems. Amino acid functionalized nickel ferrite nanoparticles were chosen to improve the stability of bare nanoparticles and prevent oxidation and leaching ions in nanoparticles thereby targeting the antibiotics in the contaminated water bodies. The removal of ciprofloxacin and lomefloxacin hydrochloride in the aqueous phase was investigated using a hydrothermally synthesized L-Leucine functionalized nickel ferrite nanocomposite (NFO@L). Various analytical techniques were used to analyze L-Leucine functionalized nickel ferrite, and the nanocomposite's average particle diameter was determined to be between 11 and 15 nm. The maximal measured zeta potential was −21.5 mV. Fourier transform infrared spectroscopy (FTIR), ninhydrin assay and X-ray diffraction (XRD) analysis confirmed the attachment of L-Leucine onto nickel ferrite. The nanocomposite's surface-to-volume ratio was calculated to be 92.916 m2/g. The S-shaped curve from the vibrating sample magnetometer analysis reflected the superparamagnetic behaviour of the nanocomposite with a saturation magnetization of 0.665 emu/g. Various parametric experiments were conducted, in which 93.549% ciprofloxacin was removed in 120 min at 303 K, pH 8 and NFO@L dosage of 100 mg in 100 mL whereas 75.192% lomefloxacin hydrochloride was removed in 140 min at 333 K, pH 9 and NFO@L dosage of 70 mg in 100 mL. The plot of experimental datum in kinetic and isotherm studies fitted well with the Pseudo second order kinetic model and Langmuir isotherm. There was no evidence of iron ions leaching from the final analyte. The recycle and regeneration studies showed good stability with a small reduction after four cycle runs. Based on these findings, the Leucine functionalized nickel ferrite nanocomposite could be a potent adsorbent for the removal of low-concentrated ciprofloxacin and lomefloxacin hydrochloride in the wastewater. © 2023
Batch and continuous studies on the removal of heavy metals from aqueous solution using biosynthesised melanin-coated PVDF membranes
(Springer, 2020) Manirethan, V.; Gupta, N.; Mohan Balakrishnan, R.M.; Raval, K.
Heavy metals like mercury, chromium, lead and copper present in groundwater at lower concentrations cause severe health issues and can even be fatal when consumed. The biopigment/biopolymer melanin can be reaped from different sources like bacterium, fungus, and human hair. It has excellent heavy metal ion scavenging property and can be exploited for non-biological applications, substantially including water purification. In this work, melanin nanoparticles were derived from the marine bacterium Pseudomonas stutzeri and were coated onto hydrophobic polyvinylidene fluoride (PVDF) membrane as a support, for batch and continuous removal of heavy metal studies. Batch studies on the effect of pH, temperature and adsorbate dose and continuous adsorption studies on the effect of flow rate, adsorbate and adsorbent mass loadings were carried out by using biosynthesised melanin-coated PVDF membranes for the removal of Hg(II), Cr(VI), Pb(II) and Cu(II). Scanning electron microscope (SEM) images revealed the surface morphology, Fourier-transform infrared spectroscopy (FTIR) and energy-dispersive X-ray spectroscopy (EDS) deciphered the chemical characteristics of melanin-coated PVDF membranes before and after adsorption. Contact angle measurement confirmed the improvement in hydrophilicity of PVDF membrane upon coating with melanin. The maximum removal percentages of heavy metals achieved by melanin-coated PVDF membranes under batch mode operation were 87.6%, 88.45%, 91.8% and 95.8% for mercury, chromium, lead and copper, respectively optimised at 318 K and pH of 3 for chromium and 5 for other metals. However, the continuous mode of operation with a flow rate of 0.5 mL/min having 1 mg/L of heavy metal solution concentration exposed to 50 mg of melanin loading with a working volume of 200 mL showed better removal efficiencies compared with batch mode. The dynamic studies using Thomas and Yoon–Nelson models described the transient stage of the breakthrough curve and the model constants were calculated for column design and scale-up. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.
Batch and continuous studies on the removal of heavy metals using biosynthesised melanin impregnated activated carbon
(Elsevier B.V., 2020) Manirethan, V.; Mohan Balakrishnan, R.M.
The adversity associated with the removal of melanin nanoparticles after adsorbing heavy metals led to the development of a system involving activated carbon on which melanin was effectively impregnated. The melanin impregnated activated carbon was handily removed from the aqueous medium by simple filtration. The batch studies performed to scrutinise the optimum conditions for maximum adsorption concluded the contact time needed to attain equilibrium to be 90 min for all metals of study. Maximum adsorption of Cr (VI) was shown at pH 3 while Hg (II), Pb (II) and Cu (II) was adsorbed efficiently at pH 5. Increase in temperature favoured the adsorption process for all metals showing maximum removal at 328 K. Melanin impregnated activated carbon could adsorb 84.59% Hg (II), 86.6% Cr (VI), 91.1% Pb (II) and 93.8% Cu (II) from 5 mg/L heavy metal solution. Dynamic studies were conducted by varying the parameters like flow rate, inlet heavy metal concentration and adsorbent loading. Optimum conditions for a maximum breakthrough was obtained with a flow rate of 0.5 mL/min, heavy metal inlet concentration of 1 mg/L and adsorbent loading of 100 mg. Experimental data modelled in equilibrium isotherms showed the best fitting with the Thomas model when compared with the Adam–Boharts model using determined coefficient and error analysis. Efficient chemical desorption of Hg (II), Pb (II) and Cu (II) was obtained using 3N HCl and Cr (VI) using 1N citric acid. © 2020 Elsevier B.V.
Bioinspired ZnS: Gd nanoparticles synthesized from an endophytic fungi Aspergillus flavus for fluorescence-based metal detection
(MDPI AG, 2019) Uddandarao, P.; Mohan Balakrishnan, R.M.; Ashok, A.; Swarup, S.; Sinha, P.
Recently, several nonconventional sources have emerged as strong hotspots for the biosynthesis of chalcogenide quantum dots. However, studies that have ascertained the biomimetic methodologies that initiate biosynthesis are rather limited. The present investigation portrays a few perspectives of rare-earth(Gd)-doped ZnS biosynthesis using the endophytic fungi Aspergillus flavus for sensing metals based on their fluorescence. Analysis of ZnS:Gd nanoparticles was performed by elemental analysis, energy-dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), photoluminescence (PL), and transmission electron microscopy (TEM). The results of TEM demonstrated that the particles were polycrystalline in nature, with a mean size of 10-18 nm. The fluorescence amenability of the biogenic ZnS nanoparticles was further used for the development of a simple and efficient sensing array. The results showed sensitive and detectable quenching/enhancement in the fluorescence of biogenic colloidal ZnS nanoparticles, in the presence of Pb (II), Cd (II), Hg (II), Cu (II) and Ni (II), respectively. The fluorescence intensity of the biogenic ZnS:Gd nanoparticles was found to increase compared to that of the ZnS nanoparticles that capacitate these systems as a reliable fluorescence sensing platform with selective environmental applications. © 2019 by the authors.
Biological synthesis of metal selenide nanoparticles and their applications
(IWA Publishing, 2021) Mohan Balakrishnan, R.M.; Kadam, V.V.
[No abstract available]
Biosynthesis and optimization of silver nanoparticles by endophytic fungus Fusarium solani
(Elsevier, 2014) Sogra Fathima, B.; Mohan Balakrishnan, R.M.
A mathematical model for optimization of factors influencing the biosynthesis of silver nanoparticles by an endophytic fungus Fusarium solani was designed. A high determination coefficient R2 of 99.3% was obtained. Structural characterization by UV-vis, TEM, XRD and FTIR revealed the formation of spherical nanoparticles. © 2014 Elsevier B.V.
Biosynthesis of cobalt oxide nanoparticles using endophytic fungus Aspergillus nidulans
(Academic Press, 2018) Vijayanandan, A.S.; Mohan Balakrishnan, R.M.
Metallic oxide nanoparticles have profound applications in electrochemical devices, supercapacitors, biosensors and batteries. Though four fungi were isolated from Nothapodytes foetida, Aspergillus nidulans was found to be suitable for synthesis of cobalt oxide nanoparticles, as it has proficient tolerance towards metal under study. The broth containing precursor solution and organism Aspergillus nidulans had changed from pink to orange indicating the formation of nanoparticles. Characterization by x-ray diffraction analysis (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and energy dispersive x-ray analysis (EDX) confirmed the formation of spinel cobalt oxide nanoparticles at an average size of 20.29 nm in spherical shape with sulfur-bearing proteins acting as a capping agent for the synthesized nanoparticles. The nanoparticles could be applied in energy storage, as a specific capacitance of 389 F/g showed competence. The study was a greener attempt to synthesize cobalt oxide nanoparticles using endophytic fungus. © 2018 Elsevier Ltd
Biosynthesis of lead selenide quantum rods in marine Aspergillus terreus
(2014) Mary Jacob, J.; Mohan Balakrishnan, R.M.; Kumar, U.B.
Biosynthesis of fluorescent, semiconductor lead selenide (PbSe) quantum rods was initiated in lead and selenium tolerant marine Aspergillus terreus. TEM and SEM images revealed the formation of rod like structures having an average diameter of 59 nm. Compositional analysis using EDAX followed by optical and structural characterization by XRD, UV-vis and FTIR spectrophotometry confirmed the biogenesis of crystalline PbSe nanoparticles with quantum confinement effects. © 2014 Elsevier B.V.
Cobalt ferrite nanoparticles and peroxymonosulfate system for the removal of ampicillin from aqueous solution
(Elsevier Ltd, 2021) Mohan Balakrishnan, R.M.; Ilango, I.; Gamana, G.; Bui, X.-T.; Arivalagan, A.
Emerging contaminants (EC) are classified as major leading issues in treating wastewater, especially drugs and pharmaceuticals in the urban regions, and the detection and degradation of these pollutants have become an arduous task. Ampicillin is one such portentous ?- lactam antibiotic compound used extensively in the medical field for their antimicrobial and growth-enhancing properties in humans as well in veterinary sectors. Due to continuous exposure, the microbes in due course developed a shield towards the implication of antibiotics. The degradation of Ampicillin has also been succeeded by mixed metal oxides nanoparticles generally specified as AxB2-xO4, which has been a fundamental catalyst in the Advanced Oxidation Process (AOPs). Magnetic nanoparticles, Cobalt Ferrite nanoparticles (CoFe2O4) were synthesized by the coprecipitation method further; it has employed in the activation of oxidizing agent Peroxymonosulfate (PMS) in the Ampicillin degradation. The material and chemical characterization of synthesized nanoparticles using XRD, TEM, SEM-EDX, and FTIR analysis were done. From the investigation, the nanoparticles were found to exhibit a cubic spinel configuration with a crystallite size of 10.10 nm. The impact of working parameters, such as the presence/absence of catalyst, pH, PMS concentration, and the time required for ampicillin degradation, were investigated. At neutral pH with 0.1 g/L of catalyst measure, 0.2 mM of PMS, 90 ± 1.94 % Ampicillin degraded over 25 min of contact time. The degraded intermediate products of Ampicillin were identified using LC–MS analysis. © 2020 Elsevier Ltd
Comprehensive insight into the extract optimization, phytochemical profiling, and biological evaluation of the medicinal plant Nothapodytes foetida
(Elsevier Ltd, 2022) Susanna, D.; Mohan Balakrishnan, R.M.; JagadeeshBabu, J.B.
Nothapodytes foetida is an endemic medicinal plant belonging to the family Icacinaceae from the deciduous forests of the Western Ghats. The extract yield, nutritional and phytochemical composition, metabolite profiling of N. foetida leaf extract has been analysed, along with the assessment of its antioxidant, anti-inflammatory, anti-microbial and anti-cancer potentialities. The effect of different extracting solvents and techniques was optimized to obtain maximum extract yield, and ultrasonication-assisted extraction with aqueous methanol as the solvent was chosen. Appreciable amounts of total phenolics (67.59 mg GAE/g DW), total flavonoids (24.75 mg QCE/g DW), and total tannins (55.67 mg GAE/g DW) were detected. FT-IR spectroscopy also confirmed the presence of alcohols, phenols, alkanes, amino acids, carboxylic acids, nitro compounds and amines in the extract. Further, GC-MS analysis detected the presence of 33 volatile compounds that comprised of viminalol, α, β-amyrins, β, γ-sitosterol, 9-methoxy-camptothecin, lupeols, and various di and tri terpenes in significant quantities. 1H NMR spectra revealed well-resolved signals for flavonoids, amino acids (trp, his, tyr, phe, ala, ile, gly, gln, thr, val) and organic acids. LC-MS analysis of the methanolic N. foetida extract depicted a higher polyphenolic content followed by the ethanolic and aqueous extracts. Additionally, the aqueous methanolic extract of N. foetida exhibited significant in-vitro antioxidant, anti-inflammatory, anti-microbial activity and anti-cancer activity. The overall results of this work ascertain the potency of N. foetida in nutraceutical and biomedical applications. © 2022
Decolorization of Reactive Blue 220 aqueous solution using fungal synthesized Co3O4 nanoparticles
(IWA Publishing 12 Caxton Street London SW1H 0QS, 2019) Valappil, R.S.K.; Vijayanandan, A.S.; Mohan Balakrishnan, R.M.
In this work, the photocatalytic activity of the biosynthesized cobalt oxide (Co3O4) nanoparticle (NP) is investigated using a textile dye Reactive Blue 220 (RB220) and decolorization % was monitored using UV–Vis spectrophotometer. The photocatalytic activity has been observed maximum at alkaline pH of 9, NP dosage of 250 mg/L, and reaction time of 270 min. In the presence of UV light irradiation, a maximum dye concentration of 10 mg/L was treated effectively using 150 mg/L NP, and 67% decolorization was achieved. Reaction kinetics has been analyzed, and the reaction followed the pseudo kinetics model with an activation energy of -484 kJ mol-1. © IWA Publishing 2019
Decolorization of Reactive Blue 220 aqueous solution using fungal synthesized Co3O4 nanoparticles
(IWA Publishing, 2020) Valappil, R.S.K.; Vijayanandan, A.S.; Mohan Balakrishnan, R.M.
In this work, the photocatalytic activity of the biosynthesized cobalt oxide (Co3O4) nanoparticle (NP) is investigated using a textile dye Reactive Blue 220 (RB220) and decolorization % was monitored using UV–Vis spectrophotometer. The photocatalytic activity has been observed maximum at alkaline pH of 9, NP dosage of 250 mg/L, and reaction time of 270 min. In the presence of UV light irradiation, a maximum dye concentration of 10 mg/L was treated effectively using 150 mg/L NP, and 67% decolorization was achieved. Reaction kinetics has been analyzed, and the reaction followed the pseudo kinetics model with an activation energy of 484 kJ mol1. © 2020 IWA Publishing.
Evaluation of photothermal properties for absorption of solar energy by Co3O4 nanofluids synthesized using endophytic fungus Aspergillus nidulans
(Elsevier Ltd, 2020) Vijayanandan, A.S.; Kandath Valappil, R.S.; Mohan Balakrishnan, R.M.
An attempt has been made to compare the optical properties of cobalt oxide (Co3O4) nanoparticles using experimental values and theoretical predictions. Optical transmittance of the nanoparticles obtained was higher than 65% in 550–850 nm containing visible spectrum and the experimental results were in accordance with the predictive datum. The absorption coefficient peak observed is close to the predictive value and is present in the visible region of the light. In addition, there was an excellent agreement between theoretical and experimental results in extinction coefficient and refractive index. Besides, this work proposes and validates a novel idea of using Co3O4 nanofluids to enhance solar thermal conversion efficiency. Co3O4 nanofluids synthesized using endophytic fungus Aspergillus nidulans isolated from a medicinal plant, Nothapodytes foetida has been used to illustrate the energy storage capacity of nanofluids. Experimental results reveal that Co3O4 nanofluids have good specific absorption rate (SAR) and better photo-thermal conversion efficiency than water. Nanofluid exhibited a greater temperature gradient than pure water, which is desired. Thus the good absorption ability of Co3O4 nanofluids for solar energy indicated that it is suitable for direct absorption solar thermal energy systems. © 2019
Exploring the fungal protein cadre in the biosynthesis of PbSe quantum dots
(Elsevier B.V., 2017) Jacob, J.M.; Sharma, S.; Mohan Balakrishnan, R.M.
While a large number of microbial sources have recently emerged as potent sources for biosynthesis of chalcogenide quantum dots (QDs), studies regarding their biomimetic strategies that initiate QD biosynthesis are scarce. The present study describes several mechanistic aspects of PbSe QD biosynthesis using marine Aspergillus terreus. Scanning electron microscopic (SEM) studies indicated distinctive morphological features such as abrasion and agglomeration on the fungal biomass after the biosynthesis reaction. Further, the biomass subsequent to the heavy metal/metalloid precursor was characterized with spectral signatures typical to primary and secondary stress factors such as thiol compounds and oxalic acid using Fourier Transform Infra-Red Spectroscopic (FTIR) analysis. An increase in the total protein content in the reaction mixture after biosynthesis was another noteworthy observation. Further, metal-phytochelatins were identified as the prominent metal-ion trafficking components in the reaction mixture using Liquid Chromatography Mass Spectroscopic analysis (LCMS). Subsequent assays confirmed the involvement of metal binding peptides namely metallothioneins and other anti-oxidant enzymes that might have played a prominent role in the microbial metal detoxification system for the biosynthesis of PbSe QDs. Based on these findings a possible mechanism for the biosynthesis of PbSe QDs by marine A. terreus has been elucidated. © 2016 Elsevier B.V.
Extraction, optimization and characterization of collagen from sole fish skin
(Elsevier B.V., 2018) Arumugam, G.K.S.; Sharma, D.; Mohan Balakrishnan, R.M.; JagadeeshBabu, P.E.
In this study, collagen was successfully extracted from marine waste i.e. Sole fish skin, which is available in the coastal area of Mangalore, India. The extraction process was optimized using One Variable at a Time (OVAT) and Response Surface Methodology (RSM) with Box-Behnken Design (BBD) was to achieve maximum yield and the extracted collagen was characterized. The optimal conditions to obtain highest collagen yield was determined to be, an acetic acid concentration of 0.54 M, NaCl concentration of 1.90 M, solvent/solid ratio of 8.97 ml/g and time of 32.32 h. The maximum collagen yield of 19.27 ± 0.05 mg/g of fish skin was achieved under the optimal conditions. The analysis of variance and contour plots exhibited a significant interaction of all the selected variables over collagen extraction process. The SDS-PAGE (Sodium dodecyl sulfate - polyacrylamide gel electrophoresis) analysis suggested that the extracted collagen contained three ?-chains i.e. (?1)2, ?2 (M.W. 118, 116 kDa) and one ? chain (M.W. 200 kDa) which was similar to commercially available calfskin Type I collagen. FT-IR (Fourier Transform Infrared Spectroscopy) analysis confirmed the existence of helical arrangements of collagen. SEM (Scanning electron microscopy) observation revealed that the extracted collagen was in the form of fibrils with irregular linkages. © 2018 Elsevier B.V.