2D Materials based Gas Sensors: Photoactivation and Defect Engineering Approach

Mahesh Kumar 한국표면공학회 2023 한국표면공학회 학술발표회 초록집 Vol.2023 No.11-1

Electrical transport studies of MBE grown InGaN/Si isotype heterojunctions

Mahesh Kumar,Basanta Roul,Mohana K. Rajpalke,Thirumaleshwara N. Bhat,A.T. Kalghatgi,S.B. Krupanidhi 한국물리학회 2013 Current Applied Physics Vol.13 No.1

The temperature dependent electrical transport behavior of nen InGaN/Si heterostructures grown by plasma-assisted MBE was studied. Structural characteristics of the as-grown InGaN epilayers were evaluated high resolution X-ray diffraction and composition of InGaN was estimated from photoluminescence spectra using standard Vegard’s law. Current densityevoltage plots (JeVeT) revealed that the ideality factor (h) and Schottky barrier height (SBH) (Fb) are temperature dependent and the incorrect values of the Richardson’s constant (A**) produced, suggests an inhomogeneous barrier at the heterostructure interface. The higher value of the ideality factor compared to the ideal value and its temperature dependence suggest that the current transport is mainly dominated by thermionic field emission.

Antibacterial and Antioxidant Potential of Methanol Extract of Viburnum sargentii Seeds

Maheshkumar Prakash Patil(마헤쉬쿠마 프라카쉬 파틸),Yeong-Ae Seong(성영애),Min-jae Kang(강민재),Alka Ashok Singh(알카 아쇽 싱),Irvine Niyonizigiye(이르빈 니요니지기에),Gun-Do Kim(김군도),Jong-Kyu Lee(이종규) 한국생명과학회 2019 생명과학회지 Vol.29 No.6

최근에 들어서 전세계적으로 식물 자원에서의 항균력 및 항산화력에 대한 관심이 광범위하게 증가하고 있다. 이는 사용되고 있는 항균제와 항산화제보다 안전한 대체 자원에 대한 관심이 높아졌기 때문으로 볼 수 있다. 따라서 본 연구에서는 Viburnum sargentii 씨앗의 메탄올 추출물의 항균력 및 항산화력과 화학적 구성에 대하여 연구를 진행하였다. 추출물의 화학 조성은 가스 크로마토 그래피-질량 분석법으로 측정하였고, 디스크 확산 분석법을 이용하여 항균 활성을 알아보았다. 액체 배지 감수성 실험을 통해 최소 억제 농도(MIC)를 측정하였고, 한천 희석법을 통해 최소 살균 농도(MBC)를 측정하였다. V. sargentii 메탄올 추출물은 실험에 사용된 그람 양성균(Listeria monocytogenes, Staphylococcus aureus, Staphylococcus saprophyticus) 및 그람 음성균(Escherichia coli, Pseudomonas putida, Proteus vulgaris)의 성장을 억제하였고, MIC와 MBC는 그람 양성균에서 0.156-1.25 mg/ml, 그람 음성균에서는 0.625-5.0 mg/ml의 범위를 나타내었다. 가스 크로마토 그래피-질량 분석법 결과에서는 V. sargentii 메탄올 추출물이 약리 활성을 가지는 β-sitosterol과 vitamin E와 같은 여러 파이토케미컬을 포함하고 있는 것을 확인하였다. V. sargentii 메탄올 추출물의 항산화 활성은 DPPH free radical scavenging assay, reducing power assay, total antioxidant capacity의 세 가지의 실험 방법을 통하여 확인하였으며, V. sargentii 메탄올 추출물의 농도가 증가함에 따라 항산화 활성도 증가하는 것을 세 가지 실험에서 모두 확인하였다. 이러한 결과를 통하여 V. sargentii 씨앗이 병원성 균의 성장을 억제할 수 있는 활성을 가질 뿐만 아니라, 항산화 활성을 가지는 구성물이 풍부함으로 추가적인 연구를 진행하기에도 충분한 가치가 있는 것을 확인하였다. Antibacterial and antioxidant activities of plant sources have attracted a wide range of interest across the world over the last decade. This is due to the growing concern for safe and alternative sources of antibacterial and antioxidant agents. In this study, we focused on the antibacterial and antioxidant activities and the chemical composition of a methanol extract from Viburnum sargentii seeds. The chemical composition was determined by gas chromatography-mass spectroscopy (GC-MS), and the antibacterial activity was screened by a disc diffusion assay. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined using the microbroth dilution and spread plate method, respectively. The V. sargentii extract showed growth inhibition activity on all tested Gram-positive (Listeria monocytogenes, Staphylococcus aureus, and Staphylococcus saprophyticus) and Gram-negative (Escherichia coli, Pseudomonas putida, and Proteus vulgaris) pathogenic bacteria. The MIC and MBC ranged from 0.156~1.25 mg/ml for Gram-positive and 0.625~5.0 mg/ml for Gram-negative tested bacteria. The GC-MS results revealed the presence of several phytochemicals such as β-sitosterol and vitamin E, which are known for their pharmacological applications. The antioxidant activities of V. sargentii extract were investigated by three different methods: the 2,2-diphenyl-1-picrylhydrazyl free radical scavenging assay, the reducing power assay, and the total antioxidant capacity assay. The results showed a concentration-dependent antioxidant potential for all three used methods. In sum, our findings suggest that the methanol extract of V. sargentii seeds has the potential to inhibit the growth of pathogenic bacteria and provide antioxidant compounds, making it therefore worthy of further investigation.

Biogenic Synthesis of Metallic Nanoparticles and Their Antibacterial Applications

Maheshkumar Prakash Patil(마헤쉬쿠마 프라카쉬 파틸),Jong-Oh Kim(김종오),Yong Bae Seo(서용배),Min-jae Kang(강민재),Gun-Do Kim(김군도) 한국생명과학회 2021 생명과학회지 Vol.31 No.9

최근 생물의학 분야에서의 광범위한 응용 가능성에 의하여 식물이나 미생물을 이용한 은(Ag), 금(Au), 백금(Pt), 세륨(Ce), 아연(Zn), 구리(Cu) 등의 금속 나노물질 합성에 관한 연구가 주목받고 있다. 식물은 플라보노이드, 알칼로이드, 사포닌, 스테로이드 탄닌과 각종 영양 성분과 같은 생리 활성 물질을 풍부하게 가지고 있으며, 유사하게 미생물들도 단백질과 같은 생리활성 대사산물이나 색소, 항생제 및 산과 같은 가치가 있는 화학물질을 분비한다. 최근 보고된 바에 의하면, 나노입자의 생체 합성은 무해한 방법일 뿐만 아니라 항균, 항진균, 세포 증식 억제 및 항플라스모디아 활성과 같은 생물의학 분야로서의 적용에 주요한 후보로 여겨진다. 나노입자의 이러한 생리 활성은 농도에 의존적이며, 나노입자의 모양과 크기에도 따라 달라질 수 있다. 미생물과 식물은 나노입자의 친환경적 합성에 사용되는 대사산물이나 화학물질 등의 훌륭한 공급원으로서 생물 의학 분야에서 유용하게 사용된다. 미생물 또는 식물 원료를 사용하여 합성된 나노입자는 화학적인 방법으로 합성된 나노입자보다 더 낮은 독성을 나타낸다. 본 리뷰논문에서는 미생물이나 식물과 같은 생물학적 재료를 이용한 나노입자의 합성과, 합성에 사용되는 다양한 기술의 특성 및 나노입자의 항균 분야에서의 적용에 대하여 중점적으로 서술하였다. Recent studies on synthesis of metallic nanomaterials such as silver (Ag), gold (Au), platinum (Pt), cerium (Ce), zinc (Zn), and copper (Cu) nanoparticles (NPs) using plants and microbes are attracted researchers for their wide range of applications in the field of biomedical sciences. The plant contains abundant of bioactive contents such as flavonoids, alkaloids, saponins, steroids tannins and nutritionals components. Similarly, microbes produce bioactive metabolites, proteins and secretes valuable chemicals such as color pigments, antibiotics, and acids. Recently reported, biogenic synthesis of NPs in non-hazardous way and are promising candidates for biomedical applications such as antibacterial, antifungal, anti-cell proliferative and anti-plasmodia activity. All those activities are dose dependent, along with their shape and size also matters on potential of NPs. Microbes and plants are great source of metabolites, those useful in biomedical field, such metabolites or chemicals involved in synthesis of NPs in an ecofriendly way. NPs synthesized using microbes or plant materials are reveals more non-toxic, facile, and cost-effective compare to chemically synthesized NPs. In present review we are focusing on NPs synthesis using biological agents such as microbes (bacteria, fungi and algae) and plant, characterization using different techniques and their antibacterial applications on pathogenic Gram-positive and Gram-negative organisms.

Effects of yoga breathing practice on heart rate variability in healthy adolescents: a randomized controlled trial

Maheshkumar Kuppusamy,Dilara Kamaldeen,Ravishankar Pitani,Julius Amaldas,Padmavathi Ramasamy,Poonguzhali Shanmugam,Venugopal Vijayakumar 한국한의학연구원 2020 Integrative Medicine Research Vol.9 No.1

Background: This study was conducted among healthy adolescents to assess the effects of a yoga breathing practice (Bhramari pranayama, Bhr.P) towards cardiac autonomic function using heart rate variability (HRV) parameters. Methods: Of the 730 eligible subjects screened, 520 healthy adolescents who met the inclusion and exclusion criteria were randomly assigned to either yoga breathing group (n = 260) or control group (n = 260). The yoga breathing group practiced Bhr.P. five days a week for a duration of six months while the control group continued with their daily routine without any intervention. Outcome measures were time and frequency domain of HRV in both groups which were assessed before and after the intervention using Lead II ECG. Linear models were used in the analysis of short term HRV. Results: After 6 months of yoga breathing, the time domain parameters of short term HRV showed significant (P < 0.05) improvement towards the parasympathetic domain. Frequency domain parameters also showed the same direction of changes. In contrast, control group subjects showed a trend towards a sympathetic domain. Conclusion: The present study showed a positive shift in cardiac autonomic modulation towards parasympathetic predominance after 6 months of yoga breathing practice among apparently healthy adolescents.

Morphological changes of bacterial cells upon exposure of silver-silver chloride nanoparticles synthesized using <i>Agrimonia pilosa</i>

Patil, Maheshkumar Prakash,Seo, Yong Bae,Kim, Gun-Do Elsevier 2018 Microbial pathogenesis Vol.116 No.-

<P><B>Abstract</B></P> <P>Facile, eco-friendly synthesis of metal nanoparticles has been proposed as a cost effective method. In the present study, we propose the facile synthesis of silver-silver chloride (Ag-AgCl) nanoparticles (NPs) using the medicinally important <I>Agrimonia pilosa</I> plant extract without addition of capping or stabilizing agents. The Ag-AgCl NPs synthesis was observed at 40 °C after 10 min incubation; the synthesis of Ag-AgCl NPs was indicated by color change and confirmed by UV-vis spectroscopic peak at 454 nm. TEM analysis confirmed Ag-AgCl NPs were 10–20 nm in size and spherical, and oval in shape. Elemental composition was determined by energy dispersive X-ray analysis, and crystalline structure was confirmed by X-ray diffraction spectroscopy. Different phytocomponents present in the plant extract were analyzed by Gas Chromatography-Mass spectrometry, and the interaction of biomolecules in reduction process was analyzed by Fourier transform infrared spectroscopy studies. The synthesized Ag-AgCl NPs showed significant antibacterial efficiency, analyzed by well diffusion assay against pathogenic bacteria including <I>Bacillus cereus</I>, <I>Listeria monocytogenes</I>, <I>Staphylococcus aureus</I>, <I>Staphylococcus saprophyticus</I>, <I>Escherichia coli</I>, <I>Pseudomonas putida</I>. Minimum inhibitory concentration and minimum bactericidal concentration were evaluated by microbroth dilution, and spread plate method, respectively. The possible mechanism of bacterial growth inhibition is due to changes in bacterial cell wall morphology that was studied by FE-SEM analysis.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Novel method for eco-friendly synthesis of Ag-AgCl nanoparticles. </LI> <LI> Synthesized Ag-AgCl nanoparticles characterized by using TEM, EDX, XRD, FT-IR and Zeta potential measurement. </LI> <LI> <I>Agrimonia pilosa</I> extract-mediated Ag-AgCl nanoparticles can be a potential antibacterial agent in therapeutics. </LI> <LI> Detail mechanism of Ag-AgCl nanoparticles mediated bactericidal activity. </LI> </UL> </P>

Marine microorganisms for synthesis of metallic nanoparticles and their biomedical applications

Patil, Maheshkumar Prakash,Kim, Gun-Do Elsevier 2018 Colloids and surfaces. B, Biointerfaces Vol.172 No.-

<P><B>Abstract</B></P> <P>Nanotechnology has become one of the most in demand technologies applied in different fields of science. Metallic nanoparticles synthesis using marine microorganisms has been received global attention due to their extensive applications in biomedical science. The use of marine microbes for metallic nanoparticles synthesis is eco-friendly, time saving, and inexpensive. An eco-friendly method is essential to minimize waste and protect environment. Recently, marine microorganisms are recognized an eco-friendly and efficient way to utilize as potential biofactories for synthesis of metallic nanoparticles. Here, we discuss and detail the possible uses of different marine microorganisms including bacteria, fungi and microalgae for metallic nanoparticle synthesis and those nanoparticles applications as antimicrobial and anticancer agents. In addition, different parameters that cause changes on nanoparticles shape and morphology are also highlighted.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Marine bacteria, fungi and microalgae highlighted for synthesis of metallic nanoparticles. </LI> <LI> Intracellular and extracellular synthesis mechanism are reviewed. </LI> <LI> Antimicrobial and anticancer applications are highlighted. </LI> <LI> Effect of reaction parameters on the morphology of nanoparticles are reviewed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Marine bacteria, fungi and microalgae mediated preparation of metallic nanoparticles and the influence of different reaction parameters on the final morphology of metallic nanoparticles.</P> <P>[DISPLAY OMISSION]</P>

Extracellular synthesis of gold nanoparticles using the marine bacterium <i>Paracoccus haeundaensis</i> BC74171^T and evaluation of their antioxidant activity and antiproliferative effect on normal and cancer cell lines

Patil, Maheshkumar Prakash,Kang, Min-jae,Niyonizigiye, Irvine,Singh, Alka,Kim, Jong-Oh,Seo, Yong Bae,Kim, Gun-Do Elsevier 2019 Colloids and surfaces. B, Biointerfaces Vol.183 No.-

<P><B>Abstract</B></P> <P>Green chemistry is beneficial for the production of eco-friendly and stable nanoparticles using biological agents. The present study was performed to explore the potential of the marine bacterium <I>Paracoccus haeundaensis</I> BC74171<SUP>T</SUP> for the extracellular synthesis of gold nanoparticles (AuNPs). Cell-free supernatant-mediated AuNPs were characterized by different techniques and analyzed for their antioxidant activity and antiproliferative effect on normal and cancer cells. Visual observations indicated the formation of AuNPs by the development of a ruby red color and were confirmed by a UV–vis absorbance peak at about 535 nm. The synthesized AuNPs were spherical in shape and had an average size of 20.93 ± 3.46 nm, as determined by transmission electron microscopy and a dynamic light scattering particle size analyzer, respectively. From Fourier transform infrared spectroscopy, the interaction of functional groups was determined and the presence of biomaterial on the AuNP surface was confirmed. Concentration-dependent antioxidant activity of AuNPs was observed by the 2,2-diphenyl-1-picrylhydrazyl method. The AuNPs synthesized do not show growth inhibition on HaCaT and HEK293 normal cells, while they show concentration-dependent growth inhibition in the case of A549 and AGS cancer cells. Thereby, this study proves that AuNP synthesis using <I>P. haeundaensis</I> is a facile method and that the AuNPs synthesized are non-toxic to human cells, which indicates that they can be useful in biomedical applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The marine bacterium <I>Paracoccus haeundaensis</I> BC74171<SUP>T</SUP> can extracellularly reduce gold ions to gold nanoparticles. </LI> <LI> Different parameters for the synthesis of gold nanoparticles were optimized. </LI> <LI> The gold nanoparticles synthesized showed non-toxicity to human normal cell lines. </LI> <LI> Gold nanoparticles have concentration-dependent antioxidant activity and an antiproliferative effect on cancer cell lines. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Green and direct functionalization of poly (ethylene glycol) grafted polymers onto single walled carbon nanotubes: Effective nanocarrier for doxorubicin delivery

Xuan Thang Cao,Maheshkumar Prakash Patil,Quoc Thang Phan,Cuong M.Q. Le,Byung-Hyun Ahn,GUN-DO KIM,임권택 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.83 No.-

This paper reports a green and direct functionalization of poly(ethylene glycol)-graft-[furfuryl-graft-(poly(styrene-alt-maleic anhydride))] (PEG-PSMF) on the surface of single walled carbon nanotubes (SWCNTs)in aqueous media through Diels-Alder (DA) click reaction. Firstly, novel PEG grafted, furfurylfunctionalized copolymers were prepared by RAFT polymerization followed by ring opening reactions. The functional copolymer was simply grafted on SWCNTs by DA reaction at room temperature underultrasonication. The resulting hybrid materials were characterized by 1H NMR, GPC, UV–vis, FT-IR, TGA,TEM, and DLS. The hybrid materials possessed a high drug loading capacity (DLC) of doxorubicin (DOX),which could reach up to 279.9 wt.% of DLC. Moreover, in vitro drug release profiles showed that drugrelease rate at pH 5.5 under an acidic condition of tumor cell microenvironment was much higher than atpH 7.4 of the physiological condition. MTT assays demonstrated that the hybrid materials did not haveany practical cytotoxicity against the normal HEK293 cell line, while drug loaded hybrids displayed a highantitumor activity towards HeLa cancer cells. This strategy offers a promising SWCNT-based drug carrierfor tumor-targeted chemotherapy.

Hydrothermal degradation of seaweed polysaccharide: Characterization and biological activities

Saravana, Periaswamy Sivagnanam,Cho, Yong-Nam,Patil, Maheshkumar Prakash,Cho, Yeon-Jin,Kim, Gun-Do,Park, Yong Beom,Woo, Hee-Chul,Chun, Byung-Soo Elsevier 2018 Food chemistry Vol.268 No.-

<P><B>Abstract</B></P> <P>Fucoidan is a marine sulfated polysaccharide that possesses various biological activities. To enhance the functional properties of fucoidan, it was depolymerized using a green technique viz. subcritical water treatment (SCW) to produce a low molecular weight fucoidan. In this study, response surface methodology (RSM) was used to study the influence of different influences for instance temperature, pressure, liquid to solid ratio, and agitation speed to depolymerize fucoidan. RSM was used to focus on the antioxidant activity and chemical composition of SCW-treated fucoidan. Further, resulting SCW-treated fucoidan was investigated by UV-Vis, FT-IR, Thermal gravimetric analysis (TGA), DSC, Elemental analysis, and ESI-MS. Moreover, the optimized SCW-treated fucoidan was checked for cytotoxicity, antimicrobial, antidiabetic, and anticoagulant activity compared with the untreated fucoidan. The obtained values displayed that SCW treatment breakdowns polymer chain and so it produces low molecular weight fucoidan. Biological activities were improved as the molecular weight was reduced.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Fucoidan was successfully depolymerized using SCW treatment. </LI> <LI> BBD was used to find the best conditions of antioxidant and chemical composition of fucoidan. </LI> <LI> The best conditions was found to be 214 °C, 40 bar, 60 mL/g, 223 RPM and 5 min. </LI> <LI> Low molecular weight of fucoidan was obtained from SCW treatment. </LI> <LI> The optimized condition showed improved biological activities from native fucoidan. </LI> </UL> </P>