Browsing by Author "Dhawan, Udesh"

Now showing 1 - 7 of 7

Layer-by-layer assembly and electrically controlled disassembly of water-solublePoly(3,4-ethylenedioxythiophene)derivatives for bioelectronic interface
(1970-01-01)
Gautam, Bhaskarchand
;
Ayalew, Hailemichael
;
Dhawan, Udesh
;
Aerathupalathu Janardhanan, Jayakrishnan
;
Yu, Hsiao-hua
Poly(3,4-ethylenedioxythiophene (PEDOT) derivatives display a multitude of attractive properties such as high conductivity, biocompatibility, ease of functionalization, and high thermal stability. As a result, they show promise for applications in materials and biomedical engineering. In order to increase their applications in the practical domain, trivial fabrication techniques are required. Here, we present a simple layer-by-layer dip methodology to assemble water-soluble PEDOT derivatives that can then be disassembled via electrical stimulation. As a result, a dynamic PEDOT layered system is fabricated and could be applied as responsive materials for bioengineering. PEDOT-SO(3)and PEDOT-NMe(3)are synthesized via direct C-H arylation polymerization and chemical polymerization, respectively. The electrostatic interactions between oppositely charged SO(3)(-)and NMe(3)(+)enabled the stacking of PEDOT derivatives. The layer-by-layer assemblies are confirmed by ultraviolet-visible spectroscopy and profilometer. Morphological analyses are performed using scanning electron microscopy and atomic force microscopy, which revealed that the polymer coatings are uniform without any cracks. In situ material assembly is studied using quartz crystal microbalance, and we also demonstrate that these PEDOT-derivative assemblies can be disintegrated by electrical stimulation. Cyclic voltammetry shows a proportional increase in stored charge density with the increase in bilayer thickness, confirming stable electroactivity of these assemblies. Using this approach, we can assemble conductive bio interface on both conductive and nonconductive surfaces, expanding the capability to fabricate bioelectronic electrodes.
Nanochip-Induced Epithelial-to-Mesenchymal Transition: Impact of Physical Microenvironment on Cancer Metastasis
(2018-04-11)
Dhawan, Udesh
;
Sue, Ming-Wen
;
Lan, Kuan-Chun
;
Buddhakosai, Waradee
;
Pao Hui Huang
Epithelial-to-mesenchymal transition (EMT) is a highly orchestrated process motivated by the nature of physical and chemical compositions of the tumor microenvironment (TME). The role of the physical framework of the TME in guiding cells toward EMT is poorly understood. To investigate this, breast cancer MDA-MB-231 and MCF-7 cells were cultured on nanochips comprising tantalum oxide nanodots ranging in diameter from 10 to 200 nm, fabricated through electrochemical approach and collectively referred to as artificial microenvironments. The 100 and 200 nm nanochips induced the cells to adopt an elongated or spindle-shaped morphology. The key EMT genes, E-cadherin, N-cadherin, and vimentin, displayed the spatial control exhibited by the artificial microenvironments. The E-cadherin gene expression was attenuated, whereas those of N-cadherin and vimentin were amplified by 100 and 200 rim nanochips, indicating the induction of EMT. Transcription factors, snail and twist, were identified for modulating the EMT genes in the cells on these artificial microenvironments. Localization of EMT proteins observed through immunostaining indicated the loss of cell cell junctions on 100 and 200 rim nanochips, confirming the EMT induction. Thus, by utilizing an in vitro approach, we demonstrate how the physical framework of the TME may possibly trigger or assist in inducing EMT in vivo. Applications in the fields of drug discovery, biomedical engineering, and cancer research are expected.
Nanochips of Tantalum Oxide Nanodots as artificial-microenvironments for monitoring Ovarian cancer progressiveness
(2016-08-18)
Dhawan, Udesh
;
Wang, Ssu-Meng
;
Chu, Ying Hao
;
Huang, Guewha S.
;
Lin, Yan Ren
Nanotopography modulates cell characteristics and cell behavior. Nanotopological cues can be exploited to investigate the in-vivo modulation of cell characteristics by the cellular microenvironment. However, the studies explaining the modulation of tumor cell characteristics and identifying the transition step in cancer progressiveness are scarce. Here, we engineered nanochips comprising of Tantalum oxide nanodot arrays of 10, 50, 100 and 200 nm as artificial microenvironments to study the modulation of cancer cell behavior. Clinical samples of different types of Ovarian cancer at different stages were obtained, primary cultures were established and then seeded on different nanochips. Immunofluorescence (IF) was performed to compare the morphologies and cell characteristics. Indices corresponding to cell characteristics were defined. A statistical comparison of the cell characteristics in response to the nanochips was performed. The cells displayed differential growth parameters. Morphology, Viability, focal adhesions, microfilament bundles and cell area were modulated by the nanochips which can be used as a measure to study the cancer progressiveness. The ease of fabrication of nanochips ensures mass-production. The ability of the nanochips to act as artificial microenvironments and modulate cell behavior may lead to further prospects in the markerless monitoring of the progressiveness and ultimately, improving the prognosis of Ovarian cancer.
Spatial Control of Cell-Nanosurface Interactions by Tantalum Oxide Nanodots for Improved Implant Geometry
(2016-06-30)
Dhawan, Udesh
;
Pan, Hsu An
;
Lee, Chia Hui
;
Chu, Ying Hao
;
Huang, Guewha Steven
Nanotopological cues can be exploited to understand the nature of interactions between cells and their microenvironment to generate superior implant geometries. Nanosurface parameters which modulate the cell behavior and characteristics such as focal adhesions, cell morphology are not clearly understood. Here, we studied the role of different nanotopographic dimensions in modulating the cell behavior, characteristics and ultimately the cell fate and accordingly, a methodology to improve implant surface geometry is proposed. Tantalum oxide nanodots of 50, 100nm dot diameter with an inter-dot spacing of 20, 70nm and heights 40, 100nm respectively, were engineered on Silicon substrates. MG63 cells were cultured for 72 hours and the modulation in morphology, focal adhesions, cell extensible area, cell viability, transcription factors and genes responsible for bone protein secretion as a function of the nanodot diameter, inter-dot distance and nanodot height were evaluated. Nanodots of 50nm diameter with a 20nm inter-dot spacing and 40nm height enhanced cell spreading area by 40%, promoted cell viability by 70% and upregulated transcription factors and genes twice as much, as compared to the 100nm nanodots with 70nm inter-dot spacing and 100nm height. Favorable interactions between cells and all dimensions of 50nm nanodot diameter were observed, determined with Scanning electron microscopy and Immunofluorescence staining. Nanodot height played a vital role in controlling the cell fate. Dimensions of nanodot features which triggered a transition in cell characteristics or behavior was also defined through statistical analysis. The findings of this study provide insights in the parameters of nanotopographic features which can vitally control the cell fate and should therefore be taken into account when designing implant geometries.
Temporal Control of Osteoblast Cell Growth and Behavior Dictated by Nanotopography and Shear Stress
(2016-10)
Dhawan, Udesh
;
Pan, Hsu-An
;
Chu, Ying Hao
;
Huang, Guewha S.
;
Chen, Po Chun
Biomaterial design involves assessment of cellular response to nanotopography parameters such as shape, dimension of nanotopography features. Here, the effect of nanotopography alongside the in vivo factor, shear stress, on osteoblast cell behavior, is reported. Tantalum oxide nanodots of 50 or 100 nm diameter were engineered using anodized aluminum oxide as a template. Bare tantalum nitride coated silicon substrates were taken as control (flat). MG63 (osteoblast) cells were seeded for 72 hours on flat, 50 or 100 nm nanodots and modulation in cell morphology, cell viability and expression of integrins was studied. Cells displayed a well-extended morphology on 50 nm nanodots in contrast to an elongated morphology on 100 nm nanodots, as observed by scanning electron microscopy and immunofluorescence staining, thereby confirming the cellular response to different nanotopographies. Based on quantitative real-time polymerase chain reaction data, a greater fold change in the expression of alpha 1, alpha 2, alpha 3, alpha 8, alpha 9, alpha V, beta 1, beta 4, beta 5, beta 7 and beta 8 integrins was observed in cells cultured on 100 nm than on 50 nm nanodots. Moreover, in the presence of a shear stress of 2 dyne/cm(2), a 52% increase in the cell viability after culturing the cells for 72 hours was observed on 100 nm nanodots as compared to 50 nm nanodots, thereby validating the effect of shear stress on cell behavior. Duration-of-culture experiments revealed 100 nm nanodots to be an ideal nanotopography choice to engineer optimized implant geometries for an ideal cell response. This study highlights the in vivo factors which need to be considered while designing nanotopographies for in vivo applications, for an ideal response as the cell-nanomaterial interface. Applications in the field of Biomedical, tissue engineering and cancer research are expected.
The Spatiotemporal Control of Osteoblast Cell Growth, Behavior, and Function Dictated by Nanostructured Stainless Steel Artificial Microenvironments
(2017-02-06)
Dhawan, Udesh
;
Pan, Hsu-An
;
Shie, Meng-Je
;
Chu, Ying Hao
;
Huang, Guewha S.
The successful application of a nanostructured biomaterial as an implant is strongly determined by the nanotopography size triggering the ideal cell response. Here, nanoporous topography on 304L stainless steel substrates was engineered to identify the nanotopography size causing a transition in the cellular characteristics, and accordingly, the design of nanostructured stainless steel surface as orthopedic implants is proposed. A variety of nanopore diameters ranging from 100 to 220 nm were fabricated by one-step electrolysis process and collectively referred to as artificial microenvironments. Control over the nanopore diameter was achieved by varying bias voltage. MG63 osteoblasts were cultured on the nanoporous surfaces for different days. Immunofluorescence (IF) and scanning electron microscopy (SEM) were performed to compare the modulation in cell morphologies and characteristics. Osteoblasts displayed differential growth parameters and distinct transition in cell behavior after nanopore reached a certain diameter. Nanopores with 100-nm diameter promoted cell growth, focal adhesions, cell area, viability, vinculin-stained area, calcium mineralization, and alkaline phosphatase activity. The ability of these nanoporous substrates to differentially modulate the cell behavior and assist in identifying the transition step will be beneficial to biomedical engineers to develop superior implant geometries, triggering an ideal cell response at the cell-nanotopography interface.
Topological control of nitric oxide secretion by tantalum oxide nanodot arrays
(2015-11-09)
Dhawan, Udesh
;
Lee, Chia Hui
;
Huang, Chun-Chung
;
Chu, Ying Hao
;
Huang, Guewha S.
Background: Nitric oxide (NO) plays a very important role in the cardiovascular system as a major secondary messenger in signaling pathway. Its concentration regulates most of the important physiological indexes including the systemic blood pressure, blood flow, regional vascular tone and other cardiac functions. The effect of nanotopography on the NO secretion in cardiomyocytes has not been elucidated before. In this study, we report how the nanotopography can modulate the secretion profile of NO and attempt to elucidate the genetic pathways responsible for the same by using Tantalum Oxide nanodot arrays ranging from 10 to 200 nm. A series of nanodot arrays were fabricated with dot diameter ranging from 10 to 200 nm. Temporal NO release of cardiomyocytes was quantified when grown on different surfaces. Quantitative RT-PCR and Western blot were performed to verify the genetic pathways of NO release. Results: After hours 24 of cell seeding, NO release was slowly enhanced by the increase of dot diameter from 10 nm up to 50 nm, mildly enhanced to a medium level at 100 nm, and increase rapidly to a high level at 200 nm. The temporal enhancement of NO release dropped dramatically on day 3. On day 5, a topology-dependent profile was established that maximized at 50 nm and dropped to control level at 200 nm. The NO releasing profile was closely associated with the expression patterns of genes associated with Endothelial nitric oxide synthase (eNOS) pathway [GPCR, PI3K, Akt, Bad, Bcl-2, NF kappa B(p65), eNOS], but less associated with Inducible nitric oxide synthase (iNOS) pathway (TNF-alpha, ILK, Akt, I kappa Ba, NF kappa B, iNOS). Western blotting of Akt, eNOS, iNOS, and NF kappa B further validated that eNOS pathway was modulated by nanotopology. Conclusions: Based on the findings of the present study, 50, 100 nm can serve as the suitable nanotopography patterns for cardiac implant surface design. These two nanodot arrays promote NO secretion and can also promote the vascular smooth muscle relaxation. The results of this study can improve the heart stent design in the medical treatments.