Browsing by Author "Kumar, Pradeep"

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Design and development of a bioactive-loaded polymer-engineered neural device for potential application in reducing neurological deficits after spinal cord injuries and neuro-regeneration
(University of the Witwatersrand, Johannesburg, 2017) Kumar, Pradeep; Choonara, Yahya Essop; Modi, Girish; Naidoo, Dinesh; Pillay, Viness
Traumatic Spinal Cord Injuries (SCI), due to their devastating nature, present several interventional challenges (extensive inflammation, axonal tethering, scar formation, neuronal degeneration and functional loss) that need to be addressed before even a slight neuronal recovery can be achieved. Recent post-TSCI investigational approaches include support strategies capable of providing scaffold architecture to allow axonal growth and conformal repair. This research provided detailed insight towards the development and fabrication of six specialized Polymer-Engineered Neural Devices (PENDs): 1) poly(lactic-co-glycolic acid)-gliadin (PLGA-GLDN) nanofibrous mats, 2) polyacrylamidated chitosan (PAAm-g-HT) scaffold, 3) functionalized chitosan methoxypolyethylene glycol (CHT-mPEG) cryosponges, 4) polyacrylonitrile-elastin-collagen (PANi-EC) neurosponge, 5) methylcellulose-alginate-polyethylene glycol (MAP) thermogel, and 6) chitosan-luronic F127-β glycerophosphate (CHT-PF127-βGP) composite thermogel for potential restriction, repair, regeneration, restoration and reorganization post-SCI. The latest trends in biomaterials-based SCI intervention were reviewed, discussed and analyzed in detail throughout the thesis. The research also involved an in silico analytico mathematical interpretation of multi(biomed)material assemblies wherein quantification of energy surfaces and molecular attributes via atomistic, dynamic, and docking simulations was carried out. The in silico experimentation additionally confirmed the potential of curcumin as a bioactive of choice for SCI intervention. Curcumin and dexamethasone were incorporated into the compact scaffolds and the bioactive release was determined over a period extending up to 60 days. The PLGA-GLDN nanofibrous mats demonstrated the formation of a compatible blend among the component polymers at equal weight ratios (PG55) as confirmed by quantitative physicochemical characterizations. Image processing analysis (DiameterJ plug-in of ImageJ) was performed on the SEM images of nanofibers to quantify the size, porosity, and orientation of the samples. Nanofibers within the size range of 10nm and 250nm were obtained in case of compatible blend and the nano stack was used for in vivo implantation post-SCI. Polyacrylamidated chitosan (PAAm-g-CHT) was synthesized via a unique persulfate-mediated polymer slicing and complexation as determined by static lattice atomistic simulations. The graft copolymer so obtained was fabricated into an anisotropic neurodurable scaffold. The CHT/mPEG cryosponges showed unique morphological features such as fringe thread-like structures (CHT alone); hemispherical, pebble-like structures (CHT-mPEG); curved quartz crystal-like or crystal-flower-like structures (CHT-mPEG-CHO); and grouped, congealed, steep-sided canyon-like structures (CHT-mPEG COOH). A novel image processing protocol involving DiameterJ and ND plugins of ImageJ software was employed for analyses of the SEM micrographs in terms of % porosity, pore wall thickness and % xiiehaviorxii of the porous scaffolds. The PANi-EC interpenetrating polymer network neurosponges were synthesized employing free radical polymerization under acidic conditions wherein first-in-the-world spinomimetic scaffolds were obtained. The unique feature of the PANi-EC neurosponge was the formation of a fibrous neurotunnel architecture mimicking the native spinal cord. The physicochemical characterization revealed that the secondary structure of the peptide molecules (elastin and collagen) rearranged in the presence of PANi to their native extracellular matrix (ECM) form confirming the self-assembling nature of the polymer-peptide architecture. Furthermore, the PANi-EC neurosponge provided a perfect balance of matrix resilience and matrix hardness similar to the native collagen-elastin complex in vivo. Two very interesting tri-component thermogels were reported here viz. a simple blend thermogel comprising methylcellulose, sodium alginate and poly(ethylene glycol) and a complex thermogel incorporating chitosan, Pluronic F127 and β-glycerophosphate. Both the thermogels solidified at physiological temperature confirming their applicability in vivo. The outstanding feature of MAP thermogels was the formation of hydrogen bonded O-H…C=O which only formed in the tripolymeric blend while the bipolymeric blends showing no such interaction. We proposed that the MAP thermogel self-assembled into a repeating network structure represented by “PEG400-ALG-hydrophillicMChydrophobic}-{hydrophobicMC-hydrophilic}-ALG-PEG400” and the physical “compression” might have led to the formation of hydrogen bonded O-H…C=O among MC/alginate or PEG/alginate in the presence of PEG or MC, respectively. In case of the complex CHT/PF127/βGP thermogel, a unique triphasic gel-sol-gel transition xiiehavior was observed with the thermogel forming a gel-phase at lower temperatures (T<20°C), a sol-phase at intermediate temperatures (20°C35°C). The MTT proliferation studies indicated that all polymer engineered neural devices (PANi-alone matrix) were capable of efficiently supporting the growth of PC12 cells compared to the control over a period of 72 hours. The fundamental objective of this thesis was to test the applicability and capability of various biomaterial composites towards the repair and regeneration of neuronal tissue after traumatic spinal cord injury. Although drug-loaded scaffolds were also developed, only drug-free scaffolds (PLGA-Gliadin 5:5 electrospun nanofibers; PANi-Elastin-Collagen neurosponge; and Chitosan/Pluronic F127/β-glycerophosphate thermogel) were tested in vivo for the proof-of-concept. The 21-point scale BBB locomotor rating analysis demonstrated that PEND I (14), PEND II (19) and PEND III (18) provided significant motor recovery as compared to the lesion-control (5) group 28 days post-SCI and –implantation. The immunohistochemistry confirmed that reparative changes were accompanied by marked upregulation of iNOS, a notable influx of ED1-positive chronic inflammatory cells, the appearance of multinucleate cells characteristic of presumptive regenerative neuroblasts and near-complete loss of GFAP and NF-200 protein/structural integrity. Almost complete functional and neurostructural recovery was observed with post-SCI implantation of PEND II and III. In conclusion, the composite scaffolds tested in this research demonstrated immense potential in improving the neurological, neurochemical, and behavioral outcome after implantation post-SCI.
Design and evaluation of a non-opioid tripartite release tablet for chronic inflammatory pain
(University of the Witwatersrand, Johannesburg, 2024) Mazarura, Kundai Roselyn; Van Eyk, Armorel; Choonara, Yahya E.; Kumar, Pradeep
Formulation-based approaches towards curbing the prescription opioid crisis include the discovery and development of non-opioid analgesics such as the novel benzyloxy- cyclopentyladenosine (BnOCPA). A more expedited approach involves the development of combinatorial systems of already existing non-addicting analgesics to tap into unexplored synergistic potentials. Despite the recent advances in drug delivery systems, tablets still hold the position of being the most widely used oral dosage form, particularly in the management of chronic ailments; it is cost-effective, non-invasive, and does not require administration expertise. Challenges in the production of complex geometry combinatorial, multi-drug tablets remain to some extent enigmatic to pharmaceutical researchers, hence the steady paradigm shift from traditional compression to 3-dimensional printing. Although it is superior in multiple aspects, the technique is still in its nascent stages with limited information on regulatory guidelines. Therefore, the aim of this work was to design and develop a non-opioid tripartite controlled- release tablet for efficient chronic inflammatory pain management. Because adherence to adjunct gastroprotective agents (GPAs) in non-steroidal anti-inflammatory drugs (NSAIDs) users has been established to be suboptimal, esomeprazole magnesium trihydrate (ESM) was added to the drug delivery system (DDS). The rationale behind the design was based on inherent drug properties, target release sites, desired therapeutic effects, and allowance for drug release manipulation, therefore a tablet was assembled, constituting an immediate- release top layer formulation of 250 mg paracetamol (PAR) for an early onset of analgesia; a cup layer for the delayed and retarded release of 100 mg of diclofenac sodium (DS) and 250 mg of PAR in tandem, and lastly a core containing a press-coated 20 mg ESM pill. A reproducible and efficient Reverse-Phase High-Performance Liquid Chromatographic (RP-HPLC) method was developed and validated for the simultaneous detection of the APIs over the concentration ranges studied. Deleterious drug-excipient incompatibilities were ruled out through pre-formulation investigations by FTIR, DSC, and TGA analyses. Combining both wet and dry granulation methodologies; the chosen formulation and polymers (7.5% hydroxypropyl methylcellulose (HPMC) K15M, 25.3% eudagrit L (EL) 100-55, and 10.5% croscarmellose sodium (CCS)), while considering the quality target product profiles (QTPPs), critical process parameters (CPP), and critical material attributes (CMAs), resulted in the development of a pragmatic tablet delivering fifty percent of the PAR dosage in the initial 30 minutes, with a cumulative release of 95.0% ± 0.08% and 94.9% ±3.87% for DS and ESM, respectively. Through in-process quality control tests, the validity of the manufacturing process was confirmed, with all results falling within pharmacopeial specifications. The release mechanism of PAR and DS from the cup after the 2-hour mark distinctly followed the Hixson-Crowell model where the geometrical characteristic of the cup was maintained with surface erosion. Visuals from scanning electron microscopy (SEM) analysis obtained prior to and during dissolution, confirmed hydration gravimetric analysis results as well as bulk and surface erosion mechanisms. The obtained ex vivo analysis results showed retarded permeation rates of the tabletted APIs compared to the APIs in their pure state. Therefore, it is imperative to consider improving the existing models employed for ex-vivo permeability studies of tableted formulations, with a particular focus on exploring the impact of excipients/polymers on drug permeation
Targeted nanosystems for tuberculosis pericarditis interventions
(University of the Witwatersrand, Johannesburg, 2024) Ayodele, Simisola Ayobami; Kumar, Pradeep; Choonara, Yahya Essop
Tuberculosis (TB) maintains its infamous status regarding its detrimental effect on global health, causing the highest mortality by a single infectious agent. It presents as the second most lethal infectious disease after HIV/AIDS. The presence of resistance and immune-compromising disease favors the disease in maintaining its footing in the health care burden despite various anti-TB drugs. The main factors contributing to resistance and difficulty in treating disease include prolonged treatment duration (at least 6 months) and severe toxicity, which further leads to patient non-compliance, and thus a ripple effect leading to therapeutic non-efficacy. The efficacy of new regimens demonstrates that targeting host factors concomitantly with the Mycobacterium tuberculosis (M.tb) strain is urgently required. Due to the huge expenses and time required of up to 20 years for new drug research and development, drug repurposing may be the most economical, circumspective, and conveniently faster journey to embark on. Host-directed therapy (HDT) will dampen the burden of the disease by acting as an immunomodulator, allowing it to defend the body against antibiotic-resistant pathogens whilst minimizing the possibility of developing new resistance to susceptible drugs. Repurposed drugs in TB act as host-directed therapies, acclimatizing the host immune cell to the presence of TB, improving its antimicrobial activity and time taken to get rid of the disease, whilst minimizing inflammation and tissue damage. Anti-TB drugs incorporated in nanosystems may reduce side effects by delivering the drug selectively into infection reservoirs such as macrophages, which may assist in clearing the TB bacilli faster and reducing the duration of therapy. Tuberculosis pericarditis (TBP) is a type of extrapulmonary tuberculosis caused by the retrograde lymphatic spread of the bacilli from lymph nodes. TBP is known to have a high burden in southern Africa due to the high prevalence of HIV and its contribution to TBP. Traditional anti-TB drugs have poor permeation across the pericardium, making TBP a difficult disease to treat with high mortality. Rapid HPLC methods were initially established for the detection and quantification of isoniazid and pyrazinamide at a physiological pH (pH 7.4). These methods were subsequently used for the detection and quantification of both compounds in the ex vivo pericardium studies. Although both drugs diffused across the pericardium, only isoniazid has anti-tubercular effects at physiological pH. Both drugs permeated across the pericardium at pH 7.4, but only isoniazid has anti-tubercular effects at this pH. Bedaquiline is known to shorten the duration of therapy but has limitations e.g., poor solubility and adverse effects such as prolongation of QT interval, causing careful use and close monitoring of its adverse effects and possible drug interactions. In this study, bedaquiline was incorporated into an inherently targeted nanosystem made of mannan (host-directed therapy) for improved permeation of the drug across the pericardium. The bedaquiline-loaded mannan-chitosan oligosaccharide lactate nanoparticles were prepared by a one-step ionic gelation probe sonication method. A PermeGear 7-in-line flow-through system was used for the ex vivo diffusion studies across porcine and human pericardium. The nano gel was loaded into the donor compartment. Phosphate buffer saline (pH 7.4 with 0.2% sodium lauryl sulphate) was pumped through the receptor compartments at 1.5 ml.h-1 (37 °C). Samples were collected every 2 h for 24 h and analyzed via HPLC. Bedaquiline loaded nanoparticles with particle size and potential of 192.4 nm and 40.5 mV, respectively, were synthesised. The chitosan-mannan bedaquiline loaded nanoparticles had an encapsulation efficacy of 98.7% and drug loading of 0.6%. Diffusion data of bedaquiline in the nanosystem indicated a flux of 2.889 and 2.346 μg.cm - 2. min -1 for porcine and human pericardium, respectively, as compared to 0.991 μg.cm-2.min-1 and 1.1578 μg.cm-2.min-1 for isoniazid and pyrazinamide, respectively. The permeation of the nanosystem indicated a consistent and linear diffusion pattern across both porcine and human pericardium, additionally approving the porcine pericardium as a great comparable tissue to human tissue for pericardial studies. The nanosystem, therefore, presents an exceptional direction for the treatment of tuberculosis pericarditis with prospectively minimized systemic side effects and host-directed therapy