Overexpression of AtNAC2 (ANAC092) in groundnut (Arachis hypogaea L.) improves abiotic stress tolerance

Mahesh Patil,T. G. Prasad,S. V. Ramu,P. Jathish,Rohini Sreevathsa,P. Chandrashekar Reddy,M. Udayakumar 한국식물생명공학회 2014 Plant biotechnology reports Vol.8 No.2

Groundnut (Arachis hypogaea L.) is animportant oilseed crop grown in semi-arid tropics where itexperiences moisture stress at different stages of growthresulting in reduced growth and productivity. In this study,we report that the stress tolerance of groundnut can beimproved by overexpression of stress-specific transcriptionfactor through transgenic approach. In silico electronicnorthernanalysis of AtNAC2 showed increased expressionunder different abiotic stresses. The transcript levels of ahomolog of AtNAC2 gene were upregulated under differentdrought regimes in groundnut. Groundnut transgenicsoverexpressing AtNAC2 showed enhanced tolerance todrought and salinity with improved yield under waterlimitedconditions. The study demonstrates that AtNAC2 isa potential candidate gene to improve stress tolerance bytransgenic approach.

In Situ Generation of Cellulose Nanocrystals in Polycaprolactone Nanofibers: Effects on Crystallinity, Mechanical Strength, Biocompatibility, and Biomimetic Mineralization

Joshi, Mahesh Kumar,Tiwari, Arjun Prasad,Pant, Hem Raj,Shrestha, Bishnu Kumar,Kim, Han Joo,Park, Chan Hee,Kim, Cheol Sang American Chemical Society 2015 ACS APPLIED MATERIALS & INTERFACES Vol.7 No.35

<P>Post-electrospinning treatment is a facile process to improve the properties of electrospun nanofibers for various applications. This technique is commonly used when direct electrospinning is not a suitable option to fabricate a nonwoven membrane of the desired polymer in a preferred morphology. In this study, a representative natural-synthetic hybrid of cellulose acetate (CA) and polycaprolactone (PCL) in different ratios was fabricated using an electrospinning process, and CA in the hybrid fiber was transformed into cellulose (CL) by post-electrospinning treatment via alkaline saponification. Scanning electron microscopy was employed to study the effects of polymer composition and subsequent saponification on the morphology of the nanofibers. Increasing the PCL content in the PCL/CA blend solution caused a gradual decrease in viscosity, resulting in smoother and more uniform fibers. The saponification of fibers lead to pronounced changes in the physicochemical properties. The crystallinity of the PCL in the composite fiber was varied according to the composition of the component polymers. The water contact angle was considerably decreased (from 124° to less than 20°), and the mechanical properties were greatly enhanced (Young’s Modulus was improved by ≈20–30 fold, tensile strength by 3–4 fold, and tensile stress by ≈2–4 fold) compared to those of PCL and PCL/CA membranes. Regeneration of cellulose chains in the nanofibers increased the number of hydroxyl groups, which increased the hydrogen bonding, thereby improving the mechanical properties and wettability of the composite nanofibers. The improved wettability and presence of surface functional groups enhanced the ability to nucleate bioactive calcium phosphate crystals throughout the matrix when exposed to a simulated body fluid solution. Experimental results of cell viability assay, confocal microscopy, and scanning electron microscopy imaging showed that the fabricated nanofibrous membranes have excellent ability for MC3T3-E1 cell proliferation and growth. Given the versatility and widespread use of cellulose–synthetic hybrid systems in the construction of tissue-engineered scaffolds, this work provides a novel strategy to fabricate the biopolymer-based materials for applications in tissue engineering and regenerative medicine.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2015/aamick.2015.7.issue-35/acsami.5b04682/production/images/medium/am-2015-04682d_0014.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am5b04682'>ACS Electronic Supporting Info</A></P>

Cellulose reinforced nylon-6 nanofibrous membrane: Fabrication strategies, physicochemical characterizations, wicking properties and biomimetic mineralization

Joshi, Mahesh Kumar,Tiwari, Arjun Prasad,Maharjan, Bikendra,Won, Ko Sung,Kim, Han Joo,Park, Chan Hee,Kim, Cheol Sang Elsevier 2016 Carbohydrate polymers Vol.147 No.-

<P><B>Abstract</B></P> <P>The aim of the present study is to develop a facile, efficient approach to reinforce nylon 6 (N6) nanofibers with cellulose chains as well as to study the effect that cellulose regeneration has on the physicochemical properties of the composite fibers. Here, a cellulose acetate (CA) solution (17wt%) was prepared in formic acid and was blended with N6 solution (20%, prepared in formic acid and acetic acid) in various proportions, and the blended solutions were then electrospun to produce hybrid N6/CA nanofibers. Cellulose was regenerated in-situ in the fiber via alkaline saponification of the CA content of the hybrid fiber, leading to cellulose-reinforced N6 (N6/CL) nanofibers. Electron microscopy studies suggest that the fiber diameter and hence pore size gradually decreases as the mass composition of CA increases in the electrospinning solution. Cellulose regeneration showed noticeable change in the polymorphic behavior of N6, as observed in the XRD and IR spectra. The strong interaction of the hydroxyl group of cellulose with amide group of N6, mainly via hydrogen bonding, has a pronounced effect on the polymorphic behavior of N6. The γ-phase was dominant in pristine N6 and N6/CA fibers while α- phase was dominant in the N6/CL fibers. The surface wettability, wicking properties, and the tensile stress were greatly improved for N6/CL fibers compared to the corresponding N6/CA hybrid fibers. Results of DSC/TGA revealed that N6/CL fibers were more thermally stable than pristine N6 and N6/CA nanofibers. Furthermore, regeneration of cellulose chain improved the ability to nucleate bioactive calcium phosphate crystals in a simulated body fluid solution.</P> <P><B>Highlights</B></P> <P> <UL> <LI> N6/CL composite fibers were obtained via electrospinning and deacetylation. </LI> <LI> Fiber diameter and pore size controlled varying the composition of component polymers. </LI> <LI> N6/CL composite fiber were more thermally stable than pristine N6 and N6/CA fibers. </LI> <LI> Wicking rate was pronouncedly enhanced due to cellulose regeneration. </LI> <LI> Tensile properties and biomimetic mineralization were improved. </LI> </UL> </P>

Multi-layered macroporous three-dimensional nanofibrous scaffold via a novel gas foaming technique

Joshi, Mahesh Kumar,Pant, Hem Raj,Tiwari, Arjun Prasad,kim, Han Joo,Park, Chan Hee,Kim, Cheol Sang Elsevier 2015 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.275 No.-

<P><B>Abstract</B></P> <P>In the past decade, considerable efforts have been made to fabricate the biomimetic scaffolds from electrospun nanofibers for tissue engineering applications. However, one of the major concerns with electrospun nanofibrous scaffolds is the densely packed fibers in two-dimensional (2-D) array which impedes their applicability in tissue regeneration. To overcome this problem, a simple and facile post-electrospinning procedure was developed to modify a densely packed 2-D electrospun membrane into low density three-dimensional (3-D) scaffolds. In this strategy, an electrospun nanofibrous mat was immersed in a sodium borohydride (SB) solution. The interconnected pores of a mat are filled with the SB solution driven by capillary forces where it undergoes hydrolysis to produce hydrogen gas. The <I>in situ</I> generated gas molecules form clusters to minimize the free energy resulting in pore nucleation that reorganizes the nanofibers to form a low density, macroporous, spongy and multi-layered 3-D scaffold. Electrospun mats of various polar and non-polar polymers were subjected to post-electrospinning process to monitor the fabrication process. It has been found that the solvent for sodium borohydride (either water or methanol) played a crucial role in post-electrospinning process. Only the electrospun mat of polar polymers were amended into 3-D architecture using aqueous SB solution while methanol solution was found equally effective for both polar and non-polar polymers. Moreover, the fabrication process was fast in methanol solution compared to an aqueous solution due to the rapid liberation of hydrogen gas from the methanolysis reaction compared to the hydrolysis reaction. This process will reveal a new approach for the fabrication of a three-dimensional, low-density, nanofibrous materials for biomedical and industrial applications using a wide variety of polymers.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Gas foaming technique is applied to prepare a 3-D nanofibrous scaffold. </LI> <LI> Sodium borohydride solution is introduced as gas foaming reagent. </LI> <LI> Novel mechanism for <I>in situ</I> gas foaming is demonstrated. </LI> <LI> Nature of the polymers affects the fabrication process. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

pH/NIR-Responsive Polypyrrole-Functionalized Fibrous Localized Drug-Delivery Platform for Synergistic Cancer Therapy

Tiwari, Arjun Prasad,Hwang, Tae In,Oh, Jung-Mi,Maharjan, Bikendra,Chun, Sungkun,Kim, Beom Su,Joshi, Mahesh Kumar,Park, Chan Hee,Kim, Cheol Sang American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.24

<P>Localized drug-delivery systems (LDDSs) are a promising approach for cancer treatment because they decrease systematic toxicity and enhance the therapeutic effect of the drugs via site-specific delivery of active compounds and possible gradual release. However, the development of LDDS with rationally controlled drug release and intelligent functionality holds great challenge. To this end, we have developed a tailorable fibrous site-specific drug-delivery platform functionalized with pH- and near-infrared (NIR)-responsive polypyrrole (PPy), with the aim of cancer treatment via a combination of photothermal ablation and chemotherapy. First, a paclitaxel (PTX)-loaded polycaprolactone (PCL) (PCL-PTX) mat was prepared by electrospinning and subsequently in situ membrane surface-functionalized with different concentrations of PPy. The obtained PPy-functionalized mats exhibited excellent photostability and heating property in response to NIR exposure. PPy-coated mats exhibited enhanced PTX release in a pH 5.5 environment compared to pH 7.4. Release was further accelerated in response to NIR under both conditions; however, superior release was observed at pH 5.5 compared to pH 7.4, indicating a dual stimuli-responsive (pH and NIR) drug-delivery platform. More importantly, the 808 nm NIR irradiation enabled markedly accelerated PTX release from PPy-coated PCL-PTX mats and slowed and sustained release following termination of laser irradiation, confirming representative stepwise drug-release properties. PPy-coated PCL-PTX mats presented significantly enhanced in vitro and in vivo anticancer efficacy under NIR irradiation compared to PPy-coated PCL-PTX mats not exposed to NIR or uncoated mats (PCL-PTX). This study has thus developed a promising fibrous site-specific drug-delivery platform with NIR- and pH-triggering that notably utilizes PPy as a dopant for synergistic photothermal chemotherapy.</P> [FIG OMISSION]</BR>

Nano-Nets Covered Composite Nanofibers with Enhanced Biocompatibility and Mechanical Properties for Bone Tissue Engineering

Tiwari, Arjun Prasad,Joshi, Mahesh Kumar,Park, Chan Hee,Kim, Cheol Sang American Scientific Publishers 2018 Journal of Nanoscience and Nanotechnology Vol.18 No.1

<P>Enhancing the biocompatibility profiles including cell attachment, growth, and viability and mechanical properties of designed synthetic scaffolds have an essential role in tissue engineering applications. Polymer blending is one of the most effective methods for providing new anticipated biomaterials for tissue scaffolds. Here, the blend solution of the different mass weight ratio of polycaprolactone (PCL) to human serum albumin (HSA) was subjected to fabricate nanocomposite spider-web-like membranes using electrospinning process. The physicochemical aspects of fabricated membranes had been characterized by a different state of techniques like that of scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA), contact angle meter and universal testing machine. FE-SEM images revealed that all PCL/HSA mats were composed of interlinked nano-nets along with conventional electro-spun fibers while nano-nets were not found for pristine PCL mat. Moreover, composite membranes exhibited improved water absorbability, enhanced biodegradation compared to pristine PCL membrane and had much better mechanical properties (tensile strength increased by up to 3-fold, Young's modulus by 2-fold). The cell attachment and proliferation tests were carried by culturing Mc3T3-E1 (pre-osteoblasts) with the designated nanofibrous membranes. The hybrid nanofibers exhibited extraordinary support for the adhesion and proliferation of cells when compared to the pristine PCL membrane. These results indicate that the nano-nets supported PCL/HSA scaffolds can be promising for tissue engineering applications.</P>

Heterogeneous electrospun polycaprolactone/polyethylene glycol membranes with improved wettability, biocompatibility, and mineralization

Tiwari, Arjun Prasad,Joshi, Mahesh Kumar,Lee, Joshua,Maharjan, Bikendra,Ko, Sung Won,Park, Chan Hee,Kim, Cheol Sang Elsevier 2017 Colloids and surfaces. A, Physicochemical and engi Vol.520 No.-

<P><B>Abstract</B></P> <P>Polycaprolactone (PCL) based electrospun membranes possess many favorable characteristics such as flexibility, high mechanical properties, and non-toxicity, all of which are required for tissue engineering applications. However, their hydrophobic nature and low biocompatibility limit their uses. To overcome these drawbacks, we propose highly biocompatible and hydrophilic heterogeneous scaffolds from a blend of PCL with polyethylene glycol (PEG) that is composed of nano-nets along with backbone/main fibers via an electro-spinning/netting (ESN) technique. Different scaffolds were fabricated by varying the mass composition of PCL to PEG and evaluated physicochemically and biologically. Scanning electron microscopy showed that the PCL/PEG membranes were of a bimodal structure consisting of backbone/main fibers (diameter range=350–600nm) and ultrathin nano-nets while the pure PCL mat was composed of only backbone fibers (diameter range=550–800nm). The nano-nets were composed of ultrathin nano-wires with an average diameter of 10–20nm, shaped in a hexagonal form. We have also prepared the PCL/PEG membranes without nano-nets and compared them to heterogeneous membranes in order to describe the effect of the nano-nets by well distinguishing the effect of PEG on tissue engineering applications such as wettability, biocompatibility, and biomineralization. The results showed that heterogeneous scaffolds exhibit enhanced wettability, mechanical stability, biocompatibility, and mineralization compared to pure PCL and PCL/PEG scaffolds without nano-nets, which confirmed that the nano-nets in the membranes had positive effects for tissue engineering applications. Findings from this study have revealed that the heterogeneous fibrous membrane could be useful in the design and tailoring of a suitable structure as a scaffold for bone tissue engineering.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Heterogeneous fibrous membrane was reported from PCL/PEG first time via electro-spinning/netting (ESN). </LI> <LI> Heterogeneous membrane was consisting of thicker/backbone fibers and ultrathin nano-nets. </LI> <LI> Hydrophilicity and mineralization were improved with incorporation of PEG into PCL fibers. </LI> <LI> Heterogeneous scaffolds showed better support for cell activities. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Formation of lipophilic drug-loaded human serum albumin nanofibers with the aid of glutathione

Tiwari, Arjun Prasad,Joshi, Mahesh Kumar,Maharjan, Bikendra,Lee, Joshua,Park, Chan Hee,Kim, Cheol Sang Elsevier 2017 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.313 No.-

<P><B>Abstract</B></P> <P>We report an efficient approach for the fabrication of hydrophobic drug-loaded human serum albumin nanofibers for the first time. The successful formation of nanofibers was found closely related to the glutathione (GSH) concentration, solution temperature, and heating time. As-fabricated nanofibers were characterized by electron microscopy, Fourier transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD). The electron micrographs show that nanofibers have cylindrical morphology and diameters of 70–120nm and lengths of up to few micrometers with a smooth surface. GSH was found to contribute to the quicker unfolding of the HSA under high temperature (80–85°C) which resulted in the strong interaction with paclitaxel, leading to a morphological transformation from nanoparticles to nanofibers. In addition, the possible mechanisms of nanofiber formation have been discussed.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Hydrophobic drug (paclitaxel) loaded human serum albumin nanofiber is reported for the first time. </LI> <LI> Facile strategy to produce albumin fibers encapsulated with a hydrophobic drug. </LI> <LI> Glutathione concentration, solution temp, and heating time affected the nanofiber formation. </LI> <LI> Time-lapsed electron microscopy images confirmed three stages in fiber formation. </LI> <LI> Spherical particles evolved into cylindrical fibers in response to continuous heating. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

In-situ synthesis of AgNPs in the natural/synthetic hybrid nanofibrous scaffolds: Fabrication, characterization and antimicrobial activities

Maharjan, Bikendra,Joshi, Mahesh Kumar,Tiwari, Arjun Prasad,Park, Chan Hee,Kim, Cheol Sang Elsevier 2017 Journal of the mechanical behavior of biomedical m Vol.65 No.-

<P><B>Abstract</B></P> <P>Silver nanoparticles embedded within a nanofibrous polymer matrix have significant attention in recent years as an antimicrobial wound dressing materials. Herein, we have fabricated a novel Ag-polyurethane-zein hybrid nanofibrous scaffold for wound dressing applications. AgNPs were synthesized in-situ via reduction of silver nitrate in electrospinning solution. Varying mass composition of the components showed the pronounced effect on the morphology and physicochemical properties of the composite fibers. Field-Emission Scanning Electron Microscopy (FESEM) images revealed that PU and zein with mass ratio 2:1 produced the bead-free continuous and uniformly distributed nanofibers. Fourier-transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD) and Thermogravimetric Analysis (TGA) confirmed the well interaction between component polymers. Compared to the pristine PU nanofibers, composite fibers showed enhanced tensile strength, young׳s modulus and surface wettability. The antibacterial capacity of the nanofibrous membrane was evaluated against gram-positive (<I>Staphylococcus aureus</I>) and gram-negative (<I>Escherichia coli</I>) bacterial strains via a zone of inhibition test, and the results showed high antibacterial performance for Ag incorporated composite mat. Experimental results of cell viability assay and microscopic imaging revealed that as-fabricated scaffolds have an excellent ability for fibroblast cell adhesion, proliferation and growth. Overall, as-fabricated antibacterial natural/synthetic composite scaffold can be a promising substrate for repairing skin defects.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A novel antibacterial natural/synthetic hybrid nanofibrous scaffold. </LI> <LI> Synthetization of AgNPs by in-situ reduction of silver nitrate in solution. </LI> <LI> Wettability and bioactivity of PU fiber improved by blending with biopolymer zein. </LI> <LI> Composite fibers showed enhanced tensile strength and young’s modulus. </LI> <LI> As-fabricated composite scaffold can be promising substrate for skin repairing. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Improved properties & fatigue resistant behaviour OF Ba(Zr0.15Ti0.85)O3 ferroelectric ceramics

M.L.V. Mahesh,Prem Pal,V.V. Bhanu Prasad,A.R. James 한국물리학회 2020 Current Applied Physics Vol.20 No.12

The microstructure, dielectric and piezoelectric properties of Zr doped BaTiO3 ceramics sintered at optimum temperature, are investigated. High energy ball milling technique is adopted to realize nano-sized powders of Ba (Zr0.15Ti0.85)O3 ceramics. Increased boundary mobility of fine powders aided to obtain a relative density of >98.8% of theoretical density corresponding to ceramics under study. Internal stresses in these ceramics are found to be relieved by grain-boundary sliding. The Ba(Zr0.15Ti0.85)O3 ceramics synthesized at relatively low sintering temperatures exhibit remarkable, enhanced dielectric properties viz. improved polarization, high unipolar strain values comparable to Zr doped BaTiO3 single crystals of same composition, at relatively lower electric fields and also exhibit better fatigue tolerant properties. The underlying mechanisms responsible for superior dielectric, ferroelectric and piezoelectric properties are discussed.