Arindom Sen | University of Calgary (original) (raw)

Papers by Arindom Sen

Polymers

Linear and crosslinked polymers are commonly used in the oil and gas industry. Guar-derived polym... more Linear and crosslinked polymers are commonly used in the oil and gas industry. Guar-derived polymers have been extensively utilized in hydraulic fracturing processes, and recently polyacrylamide and cellulose-based polymers have also found utility. As these polymers are used during various phases of the hydraulic fracturing process, they can accumulate at formation fracture faces, resulting in undesired filter cakes that impede oil and gas recovery. Although acids and chemical oxidizers are often added in the fracturing fluids to degrade or ‘break’ polymer filter cakes, the constant use of these chemicals can be hazardous and can result in formation damage and corrosion of infrastructure. Alternately, the use of enzymes is an attractive and environmentally friendly technology that can be used to treat polymer accumulations. While guar-linkage-specific enzyme breakers isolated from bacteria have been shown to successfully cleave guar-based polymers and decrease their molecular weight...

World Neurosurgery

BACKGROUND Creating aneurysm sizes in animal models that resemble human aneurysms is essential to... more BACKGROUND Creating aneurysm sizes in animal models that resemble human aneurysms is essential to study and test neuroendovascular devices. The commonly used rabbit surgical elastase model, however, produces saccular aneurysms that are smaller than those typically treated in humans. The goal of this study was to determine whether an increased vessel stump length and the addition of calcium chloride to the incubation solution has an effect on the resulting aneurysm size. METHODS Using a modified aneurysm creation method, thirty two female New Zealand White rabbits underwent aneurysm creation procedures. Subjects were equally allocated into four different groups based on vessel stump length (2 cm controls versus 3 cm) and incubation solution (elastase alone controls versus a 1:1 mixture of elastase and calcium chloride). At four weeks, all animals underwent angiography to determine the resulting aneurysm size by a neurointerventionalist that was blinded to treatment group. RESULTS An increase in stump length from 2 cm to 3 cm resulted in a significant increase in the height of aneurysm (p<0.05). Compared with control animals, the combination of a 3 cm stump length and the addition of calcium chloride to the incubation solution resulted in a significant increase in aneurysm height, width, and volume (p<0.05). CONCLUSION Creating larger aneurysms is necessary for the rabbit model to be more clinically relevant. Our study demonstrated that the utilization of a 3 cm vessel stump as well as both calcium chloride and elastase in the incubation solution results in aneurysm sizes that more closely resemble the population of aneurysms treated in humans.

Stroke, 2016

Introduction: Recurrence of intracranial aneurysms following endovascular therapy in 20% of patie... more Introduction: Recurrence of intracranial aneurysms following endovascular therapy in 20% of patients remains the only major disadvantage of this treatment. For this reason, a significant amount of research has been carried out, focused on reducing the incidence of recurrence. In recent years, a variety of cell therapy modalities using fibroblasts, smooth muscle cells, endothelial progenitor cells and Mesenchymal Stem/Stromal Cells (MSCs) have been tested in animal models as a means to improve the outcome of the treatment. However, it remains unclear whether preventing recurrence using cell therapy is a more cost-effective alternative to retreating recanalized aneurysms. In this study, we have used a Markov model approach to determine efficacy thresholds at which combined coiling and cell therapy becomes a more cost-effective treatment than coiling alone. Hypothesis: Combined coiling and cell therapy will be more cost-effective than coiling alone, if it reduces the need for retreatme...

Journal of Biotechnology, 2022

Carboxymethyl cellulose (CMC) is often used during hydraulic fracturing (fracking) operations as ... more Carboxymethyl cellulose (CMC) is often used during hydraulic fracturing (fracking) operations as a fluid viscosifier to facilitate proppant delivery. However, the accumulation of residual CMC at fracture faces can result in formation damage, thereby impeding oil and gas recovery. Whereas harsh chemical oxidizers are typically added to disrupt these polymer accumulations, there is now industrial interest in developing clean, biological approaches for the degradation of CMC under fracking conditions. Using a methanogenic culture known to utilize CMC under conditions typically found in oil fields, we developed an efficient method to isolate and purify CMC-degrading enzymes. Initial purification and concentration of cellular components produced an increase in exo-ß-(1,4)-exoglucanase and ß-(1,4)-glucosidase activities by 9-fold and 26-fold, respectively. Partially purified extracts provided substantial degradation of CMC as monitored by viscosity reduction within three hours at 50°C, an improvement over the untreated cell-free extract which required 48h to achieve similar viscosity values, outperforming a commercially-available cellulase preparation. Putative cellulases were identified within the isolated enzyme population, with endo-ß-(1,4)-xylanase from Caldicoprobacter faecalis hypothesized to be an important contributor to CMC degradation. This study demonstrates that enzyme technology holds great promise as a viable approach to degrade CMC accumulations under field conditions.

Stem Cells Translational Medicine, 2022

Mesenchymal progenitor cells (MPCs) have shown promise initiating articular cartilage repair, wit... more Mesenchymal progenitor cells (MPCs) have shown promise initiating articular cartilage repair, with benefits largely attributed to the trophic factors they secrete. These factors can be found in the conditioned medium (CM) collected from cell cultures, and it is believed that extracellular vesicles (EVs) within this CM are at least partially responsible for MPC therapeutic efficacy. This study aimed to examine the functionality of the EV fraction of CM compared to whole CM obtained from human adipose-derived MPCs in an in vivo murine cartilage defect model. Mice treated with whole CM or the EV fraction demonstrated an enhanced cartilage repair score and type II collagen deposition at the injury site compared to saline controls. We then developed a scalable bioprocess using stirred suspension bioreactors (SSBs) to generate clinically relevant quantities of MPC-EVs. Whereas static monolayer culture systems are simple to use and readily accessible, SSBs offer increased scalability and a...

ACS sensors, Jan 8, 2018

Glial fibrillary acidic protein (GFAP) is as an intermediate filament protein expressed by certai... more Glial fibrillary acidic protein (GFAP) is as an intermediate filament protein expressed by certain cells in the central nervous system (CNS). GFAP has been recognized as a reliable biomarker of CNS injury. However, due to the absence of rapid and easy-to-use assays for the detection of CNS injury biomarkers, measuring GFAP levels to identify CNS injury has not attained widespread clinical implementation. In the present work, we developed a polyethylenimine (PEI) coated graphene screen-printed electrode and used it for highly sensitive immunosensing of GFAP. Covalent binding of GFAP antibody to the PEI-modified electrode surface along with electrochemical impedance spectroscopy were used for detecting the change in the electrical conductivity of the electrodes. A highly linear response was recorded for various GFAP concentrations. Quantitative, selective, and label-free detection was achieved in the dynamic range of 1 pg mL-1 - 100 ng mL-1 for GFAP spiked in phosphate buffer saline, ...

BioProcessing Journal, 2004

Springer Protocols Handbooks, 2009

Abstract Neural precursor cells (NPCs) isolated from different regions of the developing or adult... more Abstract Neural precursor cells (NPCs) isolated from different regions of the developing or adult CNS may represent a new source of cells that may have utility in future cell replacement therapies aimed at treating neurodegenerative disorders. Moreover, these cells may have applications in a number of non-clinical areas from basic biological research to gene and drug delivery. However, their sparse concentration within the CNS means that they can only be isolated in small quantities, and thus need to be expanded to numbers ...

Cell Transplantation, 2013

Huntington's disease (HD) is a neurodegenerative disorder that is characterized by progressiv... more Huntington's disease (HD) is a neurodegenerative disorder that is characterized by progressive dementia, choreiform involuntary movements, and emotional deterioration. Neuropathological features include the progressive degeneration of striatal γ-aminobutyric acid (GABA) neurons. New therapeutic approaches, such as the transplantation of human neural precursor cells (hNPCs) to replace damaged or degenerated cells, are currently being investigated. The aim of this study was to investigate the potential for utilizing telencephalic hNPCs expanded in suspension bioreactors for cell restorative therapy in a rodent model of HD. hNPCs were expanded in a hydrodynamically controlled and homogeneous environment under serum-free conditions. In vitro analysis revealed that the bioreactor-expanded telencephalic (BET)-hNPCs could be differentiated into a highly enriched population of GABAergic neurons. Behavioral assessments of unilateral striatal quinolinic acid-lesioned rodents revealed a si...

Biotechnology Progress, 2008

Biotechnology Progress, 2006

$Research paper thumbnail of Enzyme biotechnology development for treating polymers in hydraulic fracturing operations$

Microbial Biotechnology, 2021

Carboxymethyl cellulose (CMC) is a polymer used in many different industrial sectors. In the oil ... more Carboxymethyl cellulose (CMC) is a polymer used in many different industrial sectors. In the oil and gas industry, CMC is often used during hydraulic fracturing (fracking) operations as a thickening agent for effective proppant delivery. Accumulations of CMC at fracture faces (known as filter cakes) can impede oil and gas recovery. Although chemical oxidizers are added to disrupt these accumulations, there is industrial interest in developing alternative, enzyme‐based treatments. Little is known about CMC biodegradation under fracking conditions. Here, we enriched a methanogenic CMC‐degrading culture and demonstrated its ability to enzymatically utilize CMC under the conditions that typify oil fields. Using the extracellular enzyme fraction from the culture, significant CMC viscosity reduction was observed between 50 and 80˚C, at salinities up to 20% (w/v) and at pH 5–8 compared to controls. Similar levels of viscosity reduction by extracellular enzymes were observed under oxic and ...

The Canadian Journal of Chemical Engineering

Sensors and Actuators B: Chemical, 2017

Abstract S100 calcium-binding protein β (S100β), a member of the S100 protein family, is one of t... more Abstract S100 calcium-binding protein β (S100β), a member of the S100 protein family, is one of the spinal cord injury (SCI) biomarkers extensively studied for its diagnostic and prognostic potential. The concentration of S100β is found to increase in the blood and cerebrospinal fluid (CSF) after SCI. Here, we developed an electrochemical immunosensor that offers label-free and direct detection of S100β to aid the diagnosis and prognosis of SCI. A screen-printed graphene electrode was modified by electrochemically reducing nitrate from 4-nitrobenenediazonium tetrafluoroborate to an amine group. The covalent conjugation of S100β monoclonal antibody was then achieved on the electrode surface by activating the amine group using glutaraldehyde. Characterization of the electrode was implemented using differential pulse voltammetry (DPV) in presence of potassium ferricyanide (K 3 [Fe(CN) 6 ]) redox probe. Upon testing the samples on the modified electrode with different concentrations of S100β, the DPV current peak decreased with the increase in concentration of S100β biomarker. We achieved sensitive and selective label-free detection of S100β in the dynamic range of 1 pg/ml–10 4 pg/ml for samples prepared in phosphate buffer saline (PBS), artificial CSF (aCSF), and human blood serum. The performance of the immunosensor was validated by correlating the results for samples tested with commercially available enzyme-linked immunosorbent assay (ELISA) method.

The invention provides a novel method of dissociating anchorage independent and dependent cell ag... more The invention provides a novel method of dissociating anchorage independent and dependent cell aggregates. The invention also includes the cells resulting from the methods of the invention and the use of the cells in various applications requiring the generation of a single cell suspension.

Journal of Contaminant Hydrology, 2015

Laboratory scale experiments were conducted to obtain insights into factors that influence bacter... more Laboratory scale experiments were conducted to obtain insights into factors that influence bacterial transport and deposition in porous media. According to colloidal filtration theory, the removal efficiency of a filter medium is characterized by two main factors: collision efficiency and sticking efficiency. In the case of bacterial transport in porous media, bacteria attached to a solid surface can establish a thin layer of biofilm by excreting extracellular polymeric substances which can significantly influence both of these factors in a porous medium, and thus, affect the overall removal efficiency of the filter medium. However, such polymeric interactions in bacterial adhesion are not well understood and a method to calculate polymeric interactions is not yet available. Here, to determine how the migration of bacteria flowing within a porous medium is affected by the presence of surface-associated extracellular polymeric substances previously produced and deposited by the same bacterial species, a commonly used colloidal filtration model was applied to study transport and deposition of Pseudomonas fluorescens in small-scale columns packed with clean and biofilm coated glass beads. Bacterial recoveries were monitored in column effluents and used to quantify biofilm interactions and sticking efficiencies of the biofilm coated packed-beds. The results indicated that, under identical hydraulic conditions, the sticking efficiencies in packed-beds were improved consistently by 36% when covered by biofilm.

Journal of Tissue Engineering and Regenerative Medicine

Osteoarthritis (OA) is a painful disease, characterized by progressive surface erosion of articul... more Osteoarthritis (OA) is a painful disease, characterized by progressive surface erosion of articular cartilage. The use of human articular chondrocytes (hACs) sourced from OA patients has been proposed as a potential therapy for cartilage repair, but this approach is limited by the lack of scalable methods to produce clinically relevant quantities of cartilage‐generating cells. Previous studies in static culture have shown that hACs co‐cultured with human mesenchymal stem cells (hMSCs) as 3D pellets can upregulate proliferation and generate neocartilage with enhanced functional matrix formation relative to that produced from either cell type alone. However, because static culture flasks are not readily amenable to scale up, scalable suspension bioreactors were investigated to determine if they could support the co‐culture of hMSCs and OA hACs under serum‐free conditions to facilitate clinical translation of this approach. When hACs and hMSCs (1:3 ratio) were inoculated at 20,000 cells/ml into 125‐ml suspension bioreactors and fed weekly, they spontaneously formed 3D aggregates and proliferated, resulting in a 4.75‐fold increase over 16 days. Whereas the apparent growth rate was lower than that achieved during co‐culture as a 2D monolayer in static culture flasks, bioreactor co‐culture as 3D aggregates resulted in a significantly lower collagen I to II mRNA expression ratio and more than double the glycosaminoglycan/DNA content (5.8 vs. 2.5 μg/μg). The proliferation of hMSCs and hACs as 3D aggregates in serum‐free suspension culture demonstrates that scalable bioreactors represent an accessible platform capable of supporting the generation of clinical quantities of cells for use in cell‐based cartilage repair.