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Dive into the research topics where Jayakumar Perumal is active.

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Featured researches published by Jayakumar Perumal.


Lab on a Chip | 2009

Facile single step fabrication of microchannels with varying size

Amit Asthana; Kyeong-Ohn Kim; Jayakumar Perumal; Dong-Myung Kim; Dong-Pyo Kim

In this report, we present a non-lithographic embedded template method for rapid and cost-effective fabrication of a monolithic microfluidic device with channels of various sizes. The procedure presented here enables the preparation of microchannels with varying dimensions in a single device without using any sophisticated micromachining instrumentation. In addition, this non-lithographic technique has also been used to fabricate a multilayer-multilevel biopolymer microdevice in a single step. To demonstrate the versatility of the presented method, we have fabricated microfluidic devices with four different materials under different curing/cross linking conditions. We have also demonstrated the application of the fabricated device to generate structured copper alginate microbeads, in vitro protein synthesis in three phase flow, and alternate plugs with liquid spacers.


RSC Advances | 2014

Design and fabrication of random silver films as substrate for SERS based nano-stress sensing of proteins

Jayakumar Perumal; Kien Voon Kong; U. S. Dinish; Reuben M. Bakker; Malini Olivo

We report a simple and easy to fabricate random silver film (RSF) as a highly sensitive Surface Enhanced Raman Scattering (SERS) substrate which can be fabricated directly onto a dielectric substrate such as glass. An electron beam evaporation system was used for substrate fabrication. The SERS activity is attributed to the formation of electromagnetic ‘hot-spots’ on the film. Substrate performance is analyzed by studying the reproducibility and signal enhancement from the Raman active molecule, 2-naphthalene thiol (NT), which is covalently anchored to the substrate. The metal thickness is optimized to achieve the highest SERS enhancement. Based on this study we found that a 7 nm RSF substrate gave the best SERS activity. The SERS signal intensity exhibited by 7 nm RSF is found to be at least 3 orders of magnitude higher than that of a commercial substrate. The SERS enhancement factor is estimated to be ∼1 × 107 with a point-to-point intensity variation of about 12% and it reaches a maximum of 15% for batch-to-batch comparison. The efficacy of this substrate for biosensing is demonstrated by detecting H1 influenza protein, and the detection limit is found to be ∼10 pM when it is used along with a recently established nano-stress SERS sensor, 4-ATP (4-amino-thiophenol), as linker molecule. This detection limit shows a performance superior to conventional ELISA (which has a nM detection limit). These results show promise for the development of a biosensing platform based on the marriage of RSF with nano-stress sensors.


Nanotechnology | 2009

Adhesion force measurement between the stamp and the resin in ultraviolet nanoimprint lithography—an investigative approach

Jayakumar Perumal; Tae-Ho Yoon; Hwan Soo Jang; Jae Jong Lee; Dong-Pyo Kim

In the ultraviolet nanoimprint lithography (UV-NIL) process, the surface interaction between the mold and the resist is essential along with molecularly clean separation of the mold from the surface of the cured resist for repeated use of the mold. In our present study, various mold-resin combinations have been examined by a tensile strength method to determine the adhesion force between a mold with a relief pattern and a photocurable resin. The adhesion force of polymer molds of the fluorine-containing polymers perfluoropolyether dimethacrylate (PFPE) and polydimethylsiloxane (PDMS) were compared to those of hard molds such as Si and quartz against several commercial UV-NIL resins. Eventually, PFPE with higher molecular weight-AMONIL-was found to be an excellent UV-NIL mold-resin combination with the lowest adhesion force per unit area (20 kPa). In particular, the 36-fold repeated imprinting with a high molecular weight PFPE mold showed only a slight increase of adhesion force by 36 kPa with molecularly clean release from the AMONIL resin, whereas a surface-modified PDMS mold revealed highly increased adhesion from an initial 20 kPa to 120 kPa after repeated use.


Biomicrofluidics | 2011

Bromo-oxidation reaction in enzyme-entrapped alginate hollow microfibers

Amit Asthana; Kwang Ho Lee; Su Jung Shin; Jayakumar Perumal; Lauren N. Butler; Sang Hoon Lee; Dong-Pyo Kim

In this article, the authors present the fabrication of an enzyme-entrapped alginate hollow fiber using a microfluidic device. Further use of enzyme-entrapped alginate hollow fibers as a biocatalytic microchemical reactor for chemical synthesis is also deliberated in this article. To ensure that there is no enzyme leaching from the fiber, fiber surfaces were coated with chitosan. To confine the mobility of reactants and products within the porous hollow fibers the entire fibers were embedded into a transparent polydimethylsiloxane (PDMS) matrix which also works as a support matrix. A vanadium-containing bromoperoxidase enzyme isolated from Corallina confusa was used as a model enzyme to demonstrate the use of these alginate hollow-fiber reactors in bromo-oxidation of phenol red to bromophenol blue at different dye flow rates. Stability of the entrapped enzyme at different temperatures and the effect of the chitosan coating on the reaction conversion were also studied. It was observed that molecules as big as 27 kDa can be retained in the matrix after coating with chitosan while molecules with molecular-weight of around 378 Da can still diffuse in and out of the matrix. The kinetic conversion rate in this microfluidic bioreactor was more than 41-fold faster when compared with the standard test-tube procedure.


International Journal of Nanomedicine | 2015

SERS-based quantitative detection of ovarian cancer prognostic factor haptoglobin

Jayakumar Perumal; Ghayathri Balasundaram; Aniza Puteri Mahyuddin; Mahesh Choolani; Malini Olivo

Surface-enhanced Raman spectroscopy (SERS) is increasingly being used for biosensing because of its high sensitivity and low detection limit, which are made possible by the unique Raman ‘fingerprint’ spectra from the biomolecules. Here we propose a novel SERS method for the fast, sensitive, and reliable quantitative analysis of haptoglobin (Hp), an acute phase plasma glycoprotein that is widely gaining application as a prognostic ovarian cancer biomarker. We exploited the peroxidase activity of the hemoglobin–haptoglobin (Hb–Hp) complex formed by the selective and specific binding of Hp to free Hb to catalyze the reaction of 3,3′,5,5′-tetramethylbenzidine (TMB) substrate and hydrogen peroxide to result in the final product of strongly SERS-active TMB2+. We observed a linear increase in the SERS signal of TMB2+ with increasing concentrations of Hb–Hp complex from 50 nM to 34 μM. Based on this concentration-dependent SERS spectrum, we quantified Hp in clinical samples. We observed that our inference about the prognosis of the disease coincided with the histology data and that our method was much more sensitive than the enzyme-linked immunosorbent assay method.


Biosensors | 2015

Sensing of p53 and EGFR Biomarkers Using High Efficiency SERS Substrates

Peter Owens; Nigel Phillipson; Jayakumar Perumal; Gerard M. O'Connor; Malini Olivo

In this paper we describe a method for the determination of protein concentration using Surface Enhanced Raman Resonance Scattering (SERRS) immunoassays. We use two different Raman active linkers, 4-aminothiophenol and 6-mercaptopurine, to bind to a high sensitivity SERS substrate and investigate the influence of varying concentrations of p53 and EGFR on the Raman spectra. Perturbations in the spectra are due to the influence of protein–antibody binding on Raman linker molecules and are attributed to small changes in localised mechanical stress, which are enhanced by SERRS. These influences are greatest for peaks due to the C-S functional group and the Full Width Half Maximum (FWHM) was found to be inversely proportional to protein concentration.


Journal of Materials Chemistry | 2011

Direct pattern transfer using an inorganic polymer-derived silicate etch mask

Qingling Fang; Xiaodong Li; Anh Pham Tuan; Jayakumar Perumal; Dong-Pyo Kim

Advancements in patterning materials combined with facile fabrication techniques have been critical for the development of the semiconductor industry. In order to develop a new silicate etch mask for direct pattern transfer onto silicon via etching, methacrylated polyvinylsilazane, an inorganic polymer photoresist acting as a patternable silicate precursor, was used to fabricate micron-scale patterns over a large area upon 6 inch silicon wafers by conventional photolithography. The photolithographic patterns obtained were hydrolyzed to convert the polymer phase into the silicate phase after post-heat treatment at 150 °C. The silicate patterns were transferred as an etch mask onto silicon wafers via dry plasma etching process using various ratios of an SF6/Cl2/Ar mixture as etchant. The silicate patterns revealed an excellent etching selectivity of 16 for silicon, which was 8–16 times higher than the polymer phase.


Diabetes | 2016

Retinoic Acid Mediates Visceral-specific Adipogenic Defects of Human Adipose-derived Stem Cells

Kosuke Takeda; Sandhya Sriram; Xin Hui Derryn Chan; Wee Kiat Ong; Chia Rou Yeo; Betty Tan; Su-Long Lee; Kien Voon Kong; Shawn Hoon; Hongfeng Jiang; Jason J. Yuen; Jayakumar Perumal; Madhur Agrawal; Candida Vaz; Jimmy So; Asim Shabbir; William S. Blaner; Malini Olivo; Weiping Han; Tanavde; Sue-Anne Toh; Shigeki Sugii

Increased visceral fat, rather than subcutaneous fat, during the onset of obesity is associated with a higher risk of developing metabolic diseases. The inherent adipogenic properties of human adipose-derived stem cells (ASCs) from visceral depots are compromised compared with those of ASCs from subcutaneous depots, but little is known about the underlying mechanisms. Using ontological analysis of global gene expression studies, we demonstrate that many genes involved in retinoic acid (RA) synthesis or regulated by RA are differentially expressed in human tissues and ASCs from subcutaneous and visceral fat. The endogenous level of RA is higher in visceral ASCs; this is associated with upregulation of the RA synthesis gene through the visceral-specific developmental factor WT1. Excessive RA-mediated activity impedes the adipogenic capability of ASCs at early but not late stages of adipogenesis, which can be reversed by antagonism of RA receptors or knockdown of WT1. Our results reveal the developmental origin of adipocytic properties and the pathophysiological contributions of visceral fat depots.


AIP Advances | 2017

Development of optimized nanogap plasmonic substrate for improved SERS enhancement

Jayakumar Perumal; Tianxun Gong; U. S. Dinish; Kavitha D. Buddharaju; Patrick Lo Guo-Qiang; Malini Olivo

SERS enhancement factor (EF) of planar substrates depends on the size and shape of the fine nanostructure forming a defect free, well-arranged matrix. Nano-lithographic process is considered to be the most advanced methods employed for the fabrication SERS substrates. Nanostructured plasmonic substrates with nanogap (NG) pattern often results in stable, efficient and reproducible SERS enhancement. For such substrates, NG and their diagonal length (DL) need to be optimized. Theoretically smaller NGs (∼30-40 nm or smaller) results in higher SERS enhancement. However, fabrication of NG substrates below such limit is a challenge even for the most advanced lithography process. In this context, herein, we report the optimization of fabrication process, where higher SERS enhancement can be realized from larger NGs substrates by optimizing their DL of nanostructures between the NGs. Based on simulation we could demonstrate that, by optimizing the DL, SERS enhancement from larger NG substrate such as 60 and 80 nm ...


International Journal of Nanomedicine | 2018

Identification of mycolic acid forms using surface-enhanced Raman scattering as a fast detection method for tuberculosis

Jayakumar Perumal; U. S. Dinish; Anne K Bendt; Agne Kazakeviciute; Chit Yaw Fu; Irvine Lian Hao Ong; Malini Olivo

Background Tuberculosis (TB) is the ninth leading cause of death worldwide and the leading cause from a single infectious agent, based on the WHO Global Tuberculosis Report in 2017. TB causes massive health care burdens in many parts of the world, specifically in the resource constrained developing world. Most deaths from TB could be prevented with cost effective early diagnosis and appropriate treatment. Purpose Conventional TB detection methods are either too slow as it takes a few weeks for diagnosis or they lack the specificity and accuracy. Thus the objective of this study was to develop a fast and efficient detection for TB using surface enhanced Raman scattering (SERS) technique. Methods SERS spectra for different forms of mycolic acids (MAs) that are both synthetic origin and actual extracts from the mycobacteria species were obtained by label-free direct detection mode. Similarly, we collected SERS spectra for γ-irradiated whole bacteria (WB). Measurements were done using silver (Ag) coated silicon nanopillar (Ag SNP) as SERS substrate. Results We report the SERS based detection of MA, which is a biomarker for mycobacteria species including Mycobacterium tuberculosis. For the first time, we also establish the SERS spectral characterization of the three major forms of MA – αMA, methoxy-MA, and keto-MA, in bacterial extracts and also in γ-irradiated WB. We validated our findings by mass spectrometry. SERS detection of these three forms of MA could be useful in differentiating pathogenic and nonpathogenic Mycobacterium spp. Conclusions We have demonstrated the direct detection of three major forms of MA – αMA, methoxy-MA, and keto-MA, in two different types of MA extracts from MTB bacteria, namely delipidated MA and undelipidated MA and finally in γ-irradiated WB. In the near future, this study could pave the way for a fast and efficient detection method for TB, which is of high clinical significance.

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Dong-Pyo Kim

Pohang University of Science and Technology

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Malini Olivo

National University of Ireland

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Shigeki Sugii

National University of Singapore

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Anjie Wang

Dalian University of Technology

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Zuo-Yi Xiao

Dalian Polytechnic University

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Chi Thanh Nguyen

Chungnam National University

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Hong-Joo Lee

Gwangju Institute of Science and Technology

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