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Sayan Ganguly,Subhadip Mondal,Poushali Das,Poushali Bhawal,Tushar Kanti Das,Sabyasachi Ghosh,Sanjay Remanan,Narayan Chandra Das 한국고분자학회 2019 Macromolecular Research Vol.27 No.3
Dispersion of graphene as nano-building block in polymer matrix is challenging for developing high strength polymer nanocomposites. Tuning of surface polarity can be an effective pathway to resolve this issue of dispersion. Besides this, the polymer matrix (Ethylene methyl acrylate or EMA) has been chosen here judicially due to its polar-nonpolar alternating copolymeric segments which indirectly facilitated dispersion of nanofillers. Herein, graphene oxide has been lyophilically modified by virtue of surface grafting phenomenon with the help of di-halo substituted silane. The most surprising outcome which has been nurtured is their superior dispersion, improvement in physico-mechanical features, and transparency without affecting the inherent compliance of pristine polymer. The transmission electron microscopic image of silane functionalized graphene oxide (GOF) is showing surface roughness which has immense effect of physisorption and mechanical anchoring of polymer chains over GOF nano-sheets. Such physical interaction has enough impact on mechanical properties which has been discussed here. Moreover, the deterioration of transparency was not so much affected after loading of GOF filler. The filler distribution also has been confirmed in the light of small angle X-ray scattering (SAXS) study. Thermal treatment has been conducted for composites which accounted high thermal stability comparatively to pristine polymer.
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Sayan Basak 한국생물공학회 2020 Biotechnology and Bioprocess Engineering Vol.25 No.5
Multistimuli-Responsive Nanogels are one of the most trending materials in the scope of biomedical science, which responds when excited with a range of stimuli including temperature, pH, UV light, and redox chemical moieties. These ‘smart’ nanomaterials are reported to exhibit not only higher drug/cargo release profiles, but also enhance the specificity of target delivery. This perspective aims to circumscribe the Author’s viewpoint of how these Multistimuli-Responsive Nanogels are gradually evolving and metamorphosing the biomedical sector (drug delivery, tissue engineering, gene delivery, bio-sensors, bioimaging, cell culture systems, and bio-inspired operations) with supplements from the fascinating developments in the realms of material science and nanotechnology.
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Sayan Acharya,Anup Anurag,Nithin Kolli,Subhashish Bhattacharya 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
To ramp up the adaptation of the highly optimized high current 1.2 kV Sillicon Carbide (SiC) based Metal Oxide Semiconductor Field Effect Transistor (MOSFET) power modules, a high power three-phase two-level power block is designed which is rated at 100 kVA and operates with 800 V DC bus. The power modules combined with low inductance busbar and optimized loop thermo-syphon based heatsink extracts the full performance of the power electronic switches. In this paper, the design details of the power block is presented. Furthermore, the performance of the power block is qualified by a back-to-back pump back test set up where two power blocks are interconnected via inductors. Furthermore, closed loop voltage and current control are implemented to circulate the desired amount of AC current between the power blocks. Moreover, heat run tests are carried out to quantify the thermal performance of the thermal management system. The experimental results demonstrate the performance benefits of the power block.
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( Sayan Deb Dutta ),( Keya Ganguly ),( Tejal Patel ),( Ki-taek Lim ) 한국농업기계학회 2021 한국농업기계학회 학술발표논문집 Vol.26 No.2
Mesenchymal stem cells (hMSCs) are considered as one of the promising approaches for treating several diseases in cell-based therapeutics. The current strategies for hMSCs expansion include the in vitro static culture system yielding a low number of cells. Therefore, a scalable, dynamic bioreactor-based culture system is needed to produce an adequate number of cells for clinical applications. In this study, a new strategy for hMSCs expansion is employed with a modified wave-motion bioreactor system coupled with continuous electromagnetic field (EMF) stimulation. For this purpose, hMSCs were tested in various EMF exposure (1V, 5V, and 10V-1Hz) to find the maximum viability for cell expansion. Interestingly, the hMSCs tend to form aggregate-like structures during the wave motion culture. We show that a 10V-1Hz EMF exposure (magnetic field: 5.82 G) during wave motion culture (35 rpm) induces the viability of hMSCs up to 15% than static culture as evaluated by WST-8 assay. Moreover, the long-term cell culture of hMSCs in wave bioreactor significantly enhanced the expression of osteogenic transcription factors, such as Runx2 (6.8-8.0 fold), ALP (8.0 fold), BSP (5-6.0 fold), and OCN (8-10.0 fold) compared to the static culture (28% higher as of control). We also found that the average glucose consumption was significantly higher compared to static culture as predicted by Six biosensor B.LV5. In the initial phase of cell culture, the average detectable level of glucose was 8.35±0.34 mM/μL and lactate was 0.63±0.05 mM/μL. However, after 7 days of dynamic culture, the available glucose in the media was estimated about 2.57±0.32 mM/μL and lactate was 7.67±0.26 mM/μL which was significantly higher than the static control group. The RNA-sequencing results further indicate the upregulation of major osteogenic/mechanically stimulated signaling pathways during wave motion culture of hMSCs. These results suggested that the use of 10V-1Hz (5.82 G) EMF is non-toxic for hMSCs, and the modification of wave bioreactor with externally controlled EMF has good potential for hMSCs proliferation and expansion.
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( Sayan Deb Dutta ),( Keya Ganguly ),( Tejal Patel ),( Ki-taek Lim ) 한국농업기계학회 2021 한국농업기계학회 학술발표논문집 Vol.26 No.2
3D bioprinted hydrogel has gained enormous attention, especially in tissue engineering, owing to its attractive structure and excellent biocompatibility. In this study, we demonstrated that 3D bioprinted cell-laden ‘thermoresponsive’ poloxamer-407 (P407) gels have the potential to stimulate osteogenic differentiation of apical papilla stem cells (SCAPs) under the influence of low voltage- frequency 1V-1Hz (0.14 mT), 5V-1Hz (0.62 mT), and 10V-1Hz (1.21 mT) electromagnetic fields (EMFs). Their exposure time was 5 min/day, 10 min/day, 20 min/day, and 30 min/day for each hydrogel group, respectively. The developed hydrogel exhibited higher mechanical strength as well as good printability, showing high-quality micro-architecture. Moreover, the as-printed hydrogels (5 mm × 5 mm) were loaded with plasminogen activator inhibitor-1 (PAI-1) for testing the combined effect of PAI-1 and EMFs on SCAP differentiation. Interestingly, the 3D hydrogels showed improved viability and differentiation of SCAPs under EMFs' influence as examined by live/dead assay and alizarin Red-S staining, respectively. Our results demonstrated that DSPP and DMP-1 markers' expression significantly increased (3.8-fold) in 5V (0.62 mT) EMFs treatment. A similar fashion was also observed in ALP and Col-1(2.80-fold), comparable to the control groups. Therefore, the higher expression of theses gene markers (DSPP, DMP-1 ALP, and Col-1) indicated their better osteogenic efficiency of P407-encapsulated SCAPs in the presence of EMFs. The results confirmed that P407 hydrogels are non-toxic for encapsulation of SCAPs, yielding high cell viability and accelerate the cell migration potential. The 3D hydrogels with PAI-1 exhibited high mRNA expression levels for osteogenic/odontogenic gene markers (ALP, Col-1, DSPP, and DMP-1) vis-à-vis control after 14 days of in vitro culture. Our findings suggest that 3D bioprinted P407 hydrogels are biocompatible for SCAP encapsulation, and the applied low voltage-frequency EMFs could effectively improve dental tissue regeneration, particularly for oral applications.
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Co-evolving with Nature: The Recent Trends on the Mussel-inspired Polymers in Medical Adhesion
Sayan Basak 한국생물공학회 2021 Biotechnology and Bioprocess Engineering Vol.26 No.1
The rise in the number of daily surgical procedures and the disadvantages posed by the present surgical closure techniques (such as secondary tissue damage and microbial infection) magnifies the immediate need for metamorphosing the current bioadhesives perceiving to tether wounds efficiently. To this context, the emerging scope of biomimetics has allowed mussel inspired adhesives rendering efficient bonding characteristics on a variety of substrates. The mussel adhesion proteins and its derivatives, such as 3,4-dihydroxyphenylalanine and dopamine, are therefore widely being studied to modify the biopolymers, attempting to enhance the adhesive attributes. The polarity of the catechol groups in the protein conformation aids in the development of both noncovalent interactions (electrostatic interaction, hydrogen bonding, metal/ligand coordination bond, π–π/cation-π interactions) and covalent interactions (crosslinking), thereby promoting superior tissue adhesion. This narrative is an attempt to tether the recent developments in the mussel-inspired polymer adhesives, connecting the footprints of how these materials evolved with its current state of the art.
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( Sayan Deb Dutta ),( Tusan Park ),( Keya Ganguly ),( Ki-taek Lim ) 한국농업기계학회 2021 한국농업기계학회 학술발표논문집 Vol.26 No.2
Most bone tissue-engineering models fail to demonstrate the complex cellular functions of living bone; therefore, most translational studies on bone tissue are performed in live models. To reduce the need for live models, we developed a stimulated micro-chip model for monitoring protein secretion during osteogenesis using human mesenchymal stem cells (hBMSCs). We established a bone micro-chip system for monitoring the in vitro differentiation and sensing the secreted proteins of hMSCs under a sinusoidal electromagnetic field (SEMF), which ameliorates bone healing in a biomimetic natural bone matrix. A 3V-1Hz SEMF biophysically stimulated osteogenesis by activating ERK-1/2 and promote phosphorylation of p38 MAPK kinases. Exposure to a 3V-1Hz SEMF upregulated the expression of osteogenesis-related genes, and enhanced the expression of key osteoregulatory proteins. hBMSCs undergoing osteoblastic differentiation are responsive to a well-defined SEMF stimulation at 3 V and 1 Hz, with an amplitude of 0.1 mT, for 20 minutes once a day. SEMF-treated plates contained the highest number of viable cells (>11%) compared to the other groups. Constant treatment with higher voltage, amplitude, or for a longer duration is generally counterproductive, suggesting that these parameters are optimized for this cell type. Our findings suggest that low voltage-frequency SEMF-guided osteoblast differentiation is not only triggered by the exposure time or dosage, but is also affected by various physicochemical factors. The activation of ERK1/2 and phosphorylation of p38 factors regulates the osteogenic differentiation during SEMF stimulation. Moreover, the bioinformatics analysis revealed the activation of various genes that are differentially expression only during SEMF stimulation but not in unstimulated condition. Notably, the gene expression of ALP (1.3 fold) and OCN (5.2 fold) was significantly higher (*p<0.05, **p<0.01) in cells receiving 3 V-1 Hz (0.1 mT, 20 min/day) stimulation compared to in the control. Significant increases in the expression of osteogenic gene markers were also observed for Runx2, OSX, BSP, OPN, and COL1, compared to in the unstimulated cells (*p<0.05). Six secretome proteins were upregulated in stimulated hBMSCs compared to in unstimulated hBMSCs. Overall, 23 proteins were either upregulated or downregulated by SEMF stimulation. These proteins are predicted to be secreted or included in secretory vesicles according to annotations in the Uniport database. Out of the upregulated proteins in SEMF-stimulated hBMSCs, 36% or 50% are involved in the 'immune response' or 'extracellular matrix function,' respectively. The unprecedented efficacy of our low-voltage-frequency SEMF exposure protocol for achieving hBMSC osteogenesis has broad clinical and practical implications, and could form the basis of SEMF-based therapeutic strategies for stem cell-based bone tissue regeneration. Our on-chip stimulation technology is easy to use, versatile, and non-disruptive, and should have diverse applications in regenerative medicine and cell-based therapies.
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( Sayan Deb Dutta ),( Keya Ganguly ),( Tejal Patel ),( Ki-taek Lim ) 한국농업기계학회 2021 한국농업기계학회 학술발표논문집 Vol.26 No.2
Electrical stimulation has been shown to ameliorate bone healing for a long time. This study developed a hybrid and 3D printable conductive methacrylated gelatin-polypyrrole (GelMA-PPy)-based photocurable and self-healing hydrogel inks for continuous microcurrent stimulation. For this, a custom-made electrical stimulation device (DC stimulation) was used to evaluate the osteogenic differentiation of human bone mesenchymal stem cells (hMSCs). The pyrrole was chemically grafted onto the surface of GelMA via a one-step conjugation reaction with ammonium persulfate (APS) and cross-linked with iron (III) chloride. The fabricated hydrogel was characterized by proton nuclear magnetic resonance (1H-NMR), scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) to analyze the grafting and chemical interaction. The as-prepared hydrogel exhibited higher mechanical and swelling properties compared to pure GelMA scaffolds. The 3D printed GelMA-PPy hydrogel showed improved cell viability (~12.6%) when exposed to 500 mV/day current, compared to pure GelMA after 7 and 14 days of cell culture. Interestingly,16.0~20.0-fold higher expression of osteogenic genes and protein markers (Runx2, ALP, OCN, and OPN) were observed in the GelMA-PPy treated groups than control suggest that pyrrole incorporation into GelMA matrix significantly improved the conductivity and osteogenic differentiation of hMSCs. Therefore, this study shows that the hMSCs react differentially to low-voltage DC electrical stimulation in the presence of GelMA-PPy scaffolds, which could be used as an ideal material for electrical stimulation for tissue engineering.
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Evaluation of response to stereotactic radiosurgery in patients with radioresistant brain metastases
Sayan, Mutlay,Mustafayev, Teuta Zoto,Sahin, Bilgehan,Kefelioglu, Erva Seyma Sare,Wang, Shang-Jui,Kurup, Varsha,Balmuk, Aykut,Gungor, Gorkem,Ohri, Nisha,Weiner, Joseph,Ozyar, Enis,Atalar, Banu The Korean Society for Radiation Oncology 2019 Radiation Oncology Journal Vol.37 No.4
Purpose: Renal cell carcinoma (RCC) and melanoma have been considered 'radioresistant' due to the fact that they do not respond to conventionally fractionated radiation therapy. Stereotactic radiosurgery (SRS) provides high-dose radiation to a defined target volume and a limited number of studies have suggested the potential effectiveness of SRS in radioresistant histologies. We sought to determine the effectiveness of SRS for the treatment of patients with radioresistant brain metastases. Materials and Methods: We performed a retrospective review of our institutional database to identify patients with RCC or melanoma brain metastases treated with SRS. Treatment response were determined in accordance with the Response Evaluation Criteria in Solid Tumors. Results: We identified 53 radioresistant brain metastases (28% RCC and 72% melanoma) treated in 18 patients. The mean target volume and coverage was 6.2 ± 9.5 mL and 95.5% ± 2.9%, respectively. The mean prescription dose was 20 ± 4.9 Gy. Forty lesions (75%) demonstrated a complete/partial response and 13 lesions (24%) with progressive/stable disease. Smaller target volume (p < 0.001), larger SRS dose (p < 0.001), and coverage (p = 0.008) were found to be positive predictors of complete response to SRS. Conclusion: SRS is an effective management option with up to 75% response rate for radioresistant brain metastases. Tumor volume and radiation dose are predictors of response and can be used to guide the decision-making for patients with radioresistant brain metastases.
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