Fabrication of Plasmon-Active Polymer-Nanoparticle Composites for Biosensing Applications

Abhinay Mishra,Abdul Rahim Ferhan,Chee Meng Benjamin Ho,Joohyun Lee,Dong-Hwan Kim,Young Jin Kim,Yong-Jin Yoon 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.8 No.3

Polymer-nanoparticle composites find relevance in various fields ranging from optoelectronics to the biomedical sciences. Various efforts have been made to devise fabrication strategies that are simple, robust,and reproducible. Herein, we demonstrate a universal strategy to fabricate plasmon-active polymer-nanoparticle composites, exemplified by the incorporation of gold nanoparticles (AuNPs) into a triethylene glycol dimethacrylate (TEGDMA) polymer scaffold. The TEGDMA scaffold was synthesized on a planar glass support substrate via surface-initiated atomic transfer radical polymerization, followed by the immersion of the TEGDMA-coated glass substrate in a solution of AuNPs prepared via conventional wet-chemical synthesis. This led to the strong attachment of AuNPs to the TEGDMA nanolobes, which was confirmed by the UV absorption peak at 527 nm, due to localized surface plasmon resonance of AuNPs. More importantly, the nanolobe architecture facilitates nanoparticle trapping while allowing molecular access to the nanoparticle surface. This enabled us to further functionalize the incorporated AuNPs with thrombin binding aptamer and utilize the biofunctionalized polymer-nanoparticle composite as a thrombin sensor. The synergistic combination of metallic nanoparticles acting as a sensing module with a nonfouling polymer matrix acting both as a nonrigid scaffold and to screen biomolecules allowed the detection of thrombin with good sensitivity down to 0.01 ng/mL with a linear range over three orders of magnitude. Our work paves the way for the fabrication of reliable biomolecular sensors based on the polymer brush-nanoparticle architecture.

Permanent Deformation Characteristics of Warm Asphalt Binders under Reduced Aging Conditions

Ashok Julaganti,Rajan Choudhary,Abhinay Kumar 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.1

Warm Mix Asphalt (WMA) technologies allow a 20 to 40°C reduction in production temperatures of asphalt mixes. These technologies are often synergistically combined with modified asphalt binders to tackle the increased production temperature requirements with these binders. Because of lower production temperatures, the asphalt binders containing WMA additives undergo reduced short-term aging and thus need to be examined for permanent deformation behavior at different reductions in production temperatures. The present study evaluates permanent deformation characteristics of warm asphalt binders as function of short-term aging temperature, modified binder type, and various dosages of a wax-based WMA additive: Sasobit. Experimental variables included are: three short-term aging temperatures (163°C, 143°C, and 123°C), two modified asphalt binders (polymer, and crumb rubber modified), and three contents of WMA additive (1%, 2%, and 3%). Warm binders as well as control binders are characterized in terms of viscosity, failure temperature, temperature sweep, frequency sweep, and multiple stress creep and recovery tests. WMA additive compensates the reduced stiffness of binders on being aged at lower temperatures, as rheological parameters of warm binders aged at 143°C and 123°C compare well with control binders. Statistical models for the rheological parameters as function of the experimental variables are also developed.

Transcutaneous Partial Pressure of Oxygen Measurement in Advanced Chronic Venous Insufficiency as a Marker of Tissue Oxygenation

Ludia John,Albert Abhinay Kota,Vimalin Samuel,Prabhu Premkumar,Dheepak Selvaraj,Edwin Stephen,Sunil Agarwal,Pranay Gaikwad 대한혈관외과학회 2021 Vascular Specialist International Vol.37 No.3

Purpose: Determination of oxygen concentration in tissues affected by chronic venous insufficiency (CVI) has shown inconsistent results over the years and has confounded the pathophysiology of venous diseases. This study measured transcutaneous partial oxygen pressure (TcPO2) levels in patients with CVI to assess oxygenation and variation in oxygenation according to CVI stage. Materials and Methods: A prospective study was performed on consecutive patients with unilateral CVI. TcPO2 of diseased and unaffected limbs was measured in the supine and dependent positions. A single TcPO2 value was measured at the site of greatest skin change or at the edge of the ulcer. The TcPO2 values were analyzed and compared according to stage. Results: A total of 96 patients were included in the study with C4 (24.0%), C5 (19.8%), and C6 (56.3%) disease. The mean age was 44.7 years, and 85 (88.5%) were male. There was a statistically significant (P<0.01) difference in mean TcPO2 levels between the unaffected limb (supine, 32.1 mmHg; dependent, 50.7 mmHg), C5 diseased limb (supine, 16.6 mmHg; dependent, 35.5 mmHg), and C6 diseased limb (supine, 24.2 mmHg; dependent, 40.4 mmHg). In the supine and dependent positions, the mean TcPO2 in the affected limb was significantly lower (P<0.01) than that in the unaffected limb. Conclusion: TcPO2 in advanced CVI can be used as a marker of oxygenation status. This is the first study in an Indian population looking at the relevance of TcPO2 in the prognostication of advanced CVI.

Printing of Woodpile Scaffold Using Fresnel Lens for Tissue Engineering

Chee Meng Benjamin Ho,Kan Hu,Abhinay Mishra,Jinhong Noh,Jeonghwan Kim,Suhan Lee,MinSung Yoon,Yong-Jin Yoon 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.9 No.2

Tissue engineering has played a very significant role in the medical fi eld with an ever-growing demand for various tissue donations. One crucial factor is the fabrication of a desirable artificial three-dimensional (3D) tissue scaffold to act as the extracellular matrix (ECM), meeting the complex requirements for specific cell cultures. Existing scaffold fabrication techniques and systems used in constructing extracellular matrix are two-dimensionally limiting, expensive, and time-consuming. For instance, some simple fabrication methods cannot control fabricated structures with morphologies accurately, while others may introduce harmful organic solvents into scaffolds during the fabrication processes. To achieve an optimal scaffold for tissue engineering, we developed a novel 3D printing system capable of printing tissue scaffold structures with improved efficiency. The uniqueness of our system is the transparent diffractive optical elements (DOEs) of linear binary Fresnel lens fabricated to control the luminous intensity distribution. These DOEs of different patterns are arranged in series on a coverslip with each optical element designed to diff act and focus incident light at a particular plane within the device. Coupled with other optical components of the system, 3D woodpile scaffolds were printed in an effective and efficient onestep light exposure process to photo cross-link the polymer solution upon demand. The combination of photo cross-linking and diffractive optical technique incorporated within our system enables the patterning of polymer solutions within seconds, making large-scale fast production not only feasible, but also making printing of complex features simple. With this system, 3D two-layered woodpile structures were successfully fabricated within 3 seconds. While cell toxicity studies showed that the scaffold can be used for tissue engineering.

Studies on immunomodulatory effect of endophytic fungus Alternaria alternata on Spodoptera litura

Harminder Preet Kaur,Bahaderjeet Singh,Abhinay Thakur,Amarjeet Kaur,Sanehdeep Kaur 한국응용곤충학회 2015 Journal of Asia-Pacific Entomology Vol.18 No.1

Secondary metabolites of entomopathogenic fungi have been known to suppress the immune response of various insects. Hence, we have investigated the effect of endophytic fungus, Alternaria alternata on cellular and humoral immune response of Spodoptera litura (Fabricius). Significant drop in total hemocyte count has been observed in the larvae fed on diet supplemented with ethyl acetate extract of A. alternata as compared to those fed on untreated or control diet devoid of ethyl acetate extract. Similarly differential hemocyte count of the larvae feeding on amended diet differed significantly from control. As compared to control significantly higher percentage of hemocytes exhibited abnormalities like aggregation, change in shape, extensive vacuolization and necrosis. The cytotoxic effect showed a dose dependent response which increased with time. A reduction in phenoloxidase and lysozyme activities was also observed. The data suggest that the secondary metabolites produced by A. alternata disabled several immunemechanisms of the insect. These studieswould help to identify the insect defenses that could be manipulated to accelerate host death due to fungal endophytes.