Browsing by Author "Afsar, Ashfaq"

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    Cross-linking of γ-cyclodextrin using non-toxic polyethylene glycol spacer units
    (Wiley, 2021-08-16) Dossi, Eleftheria; Bolton, Morgan; Kister, Guillaume; Afsar, Ashfaq
    The crystalline cyclic oligosaccharide γ-cyclodextrin (γCD) is a natural, non-toxic and biodegradable precursor that can be used to prepare innovative polymers. We cross-linked γCD with variable quantities of non-toxic polyethylene glycol diglycidyl ether (PEGDGE) in aqueous NaOH to form 3D structures with tunable physicochemical properties. Mixtures with a 5:1 PEGDGE:γCD molar ratio produced a cross-linked material that was soluble in water and organic solvents, underwent glass transition at –23 °C. The properties of this material were further modified by additional curing with PEGDGE or nitration reaction. Curing produced an insoluble polymeric material with excellent swelling abilities (200% in water) and decreased glass transition temperature to –37 °C. The nitrated cross-linked γCD was soluble in common organic solvents and underwent glass transition at +19 °C, achieving thermal stability below 190 °C. These novel γCD polymers are promising materials for applications in the pharmaceutical and food industries and environmental remediation.
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    Data for: Nanoindentation Response of 3D Printed PEGDA Hydrogels in a Hydrated Environment
    (Cranfield University, 2023-01-27 09:40) Hakim Khalili, Mohammad; J. Williams, Craig; Zhang, Rujing; Wilson, Sandra; Impey, Sue; Aria, Indrat; Goel, Saurav; Dossi, Licia; Afsar, Ashfaq; Duarte martinez, Fabian; Micallef, Christian
    Raw and processed data sets from nanoidentation response of 3D printed hydrogels. 1. Raw data of nanoindentation response. 2. Representative load-displacement curves for each type of hydrogel. 3. Representative data for creep for different types of hydrogels. 4. Representative data for NMR spectras of different types of hydrogels. 5. Representative data for glass transition of different types of hydrogels.
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    Data supporting 'Thermal response of multi-layer UV crosslinked PEGDA hydrogels'
    (Cranfield University, 2023-02-16 11:15) Hakim Khalili, Mohammad; Afsar, Ashfaq; Zhang, Rujing; Wilson, Sandra; Goel, Saurav; Impey, Sue; Aria, Adrianus
    All data sets are raw data from thermoresponse behaviour of hydrogels. 1. Swelling test for multi-150 um hydrogels with 1.8 mg/ml of photoabsorber.2. Swelling test for mono-5 mm hydrogels with 0 mg/ml of photoabsorber.3. Swelling test for multi-20 um hydrogels with 9 mg/ml of photoabsorber.4. Swelling test for mono-3 mm and mono-1.5 mm hydrogels with 0 mg/ml of photoabsorber.5. Cyclic test for multi-150 um hydrogels.6. Dried weight and solid residue weight of all hydrogels samples7. EWC, NWF, NVF-summary for all hydrogel samples8. DSC-TG-Thermogram-All sample types
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    Nanoindentation response of 3D printed PEGDA hydrogels in hydrated environment
    (American Chemical Society, 2023-01-20) Hakim Khalili, Mohammad; Williams, Craig J.; Micallef, Christian; Duarte-Martinez, Fabian; Afsar, Ashfaq; Zhang, Rujing; Wilson, Sandra; Dossi, Eleftheria; Impey, Susan A.; Goel, Saurav; Aria, Adrianus Indrat
    Hydrogels are commonly used materials in tissue engineering and organ-on-chip devices. This study investigated the nanomechanical properties of monolithic and multilayered poly(ethylene glycol) diacrylate (PEGDA) hydrogels manufactured using bulk polymerization and layer-by-layer projection lithography processes, respectively. An increase in the number of layers (or reduction in layer thickness) from 1 to 8 and further to 60 results in a reduction in the elastic modulus from 5.53 to 1.69 and further to 0.67 MPa, respectively. It was found that a decrease in the number of layers induces a lower creep index (CIT) in three-dimensional (3D) printed PEGDA hydrogels. This reduction is attributed to mesoscale imperfections that appear as pockets of voids at the interfaces of the multilayered hydrogels attributed to localized regions of unreacted prepolymers, resulting in variations in defect density in the samples examined. An increase in the degree of cross-linking introduced by a higher dosage of ultraviolet (UV) exposure leads to a higher elastic modulus. This implies that the elastic modulus and creep behavior of hydrogels are governed and influenced by the degree of cross-linking and defect density of the layers and interfaces. These findings can guide an optimal manufacturing pathway to obtain the desirable nanomechanical properties in 3D printed PEGDA hydrogels, critical for the performance of living cells and tissues, which can be engineered through control of the fabrication parameters.
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    Preformulation studies and bioavailability enhancement of curcumin with a ‘two in one’ PEG-β-cyclodextrin polymer
    (MDPI, 2021-10-16) Haimhoffer, Ádám; Dossi, Eleftheria; Béresová, Monika; Bácskay, Ildikó; Váradi, Judit; Afsar, Ashfaq; Rusznyák, Ágnes; Vasvári, Gábor; Fenyvesi, Ferenc
    Drug delivery systems are used to improve the biopharmaceutical properties of curcumin. Our aim was to investigate the effect of a water-soluble ‘two in one’ polymer containing covalently bonded PEG and βCD moieties (βCPCD) on the solubility and bioavailability of curcumin and compare it to a polymeric β-cyclodextrin (βCDP) cross-linked with epichlorohydrin. Phase-solubility and dynamic light scattering (DLS) experiments showed that the solubility of curcumin increased significantly in 10 m/m % βCPCD and βCDP solutions, but βCPCD–curcumin particles had higher hydrodynamic volume. The formation of the βCPCD–curcumin complex in solution and sedimented phase was confirmed by NMR spectroscopy. Biocompatibility and permeability experiments were performed on Caco-2 cells. Polymers did not show cytotoxicity up to 10 m/m % and βCPCD significantly increased the permeability of curcumin. DLS measurements revealed that among the interaction of polymers with mucin, βCPCD formed bigger aggregates compared to βCDP. Curcumin complexes were lyophilized into capsules and structurally characterized by micro-CT spectroscopy. Drug release was tested in a pH 1.2 medium. Lyophilized complexes had a solid porous matrix and both βCPCD and βCDP showed rapid drug release. βCPCD provides an opportunity to create a swellable, mucoadhesive matrix system for oral drug delivery.
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    Thermal response of multi-layer UV crosslinked PEGDA hydrogels
    (Elsevier, 2022-01-07) Khalili, Mohammad Hakim; Afsar, Ashfaq; Zhang, Rujing; Wilson, Sandra; Dossi, Eleftheria; Goel, Saurav; Impey, Susan A.; Aria, Adrianus Indrat
    Poly(ethylene glycol) diacrylate (PEGDA) hydrogels are ubiquitously used in a wide variety of applications in tissue engineering. In this study, the thermal response of multi-layered PEGDA hydrogels was investigated under various conditions of the temperature-controlled environments (8, 20, 37, and 45 °C) through gravimetric and volumetric methods. These multi-layered hydrogels were produced using a computer-controlled projection lithography and compared to the monolithic hydrogels fabricated through bulk photo-crosslinking. It was observed that the volume of multi-layered PEGDA hydrogels increased to about 10% at a temperature of 8 °C, while their volume decreased by 8% and 12% when stored at 37 °C and 45 °C, respectively. PEGDA hydrogel also showed an anisotropic characteristic where the axial dimensional change was about 43% higher than the lateral dimension. This finding is critical to inform the design and fabrication of PEGDA hydrogels to compensate for the axial and lateral volume changes during the application at different temperatures.