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Functional properties of chitosan built nanohydrogel with enhanced glucose-sensitivity

Ullah F, Othman MB, Javed F, Ahmad Z, Akil HM, Rasib SZ

Int J Biol Macromol, 2016 Feb;83:376-84.
PMID: 26597568 DOI: 10.1016/j.ijbiomac.2015.11.040

A new approach to design multifunctional chitosan based nanohydrogel with enhanced glucose sensitivity, stability, drug loading and release profile are reported. Two approaches were followed for functionalization of chitosan based nanohydrogel with 3-APBA via EDC and 3-APTES. The effective functionalization, structure and morphology of Chitosan based IPN respectively were confirmed by FTIR, SEM and AFM. At physiological conditions, the glucose-induced volume phase transition and release profile of the model drug Alizarin Red with 1,2-diol structure (comparative to insulin as a drug as well as a dye for bio separation) were studied at various glucose concentrations, pH and ionic strengths. The results suggested a new concept for diabetes treatment and diols sensitivity in view of their potential hi-tech applications in self-regulated on-off response to the treatment (drug delivery and bio separation concurrently).
Kinetic investigation and lifetime prediction of Cs-NIPAM-MBA-based thermo-responsive hydrogels

Othman MB, Khan A, Ahmad Z, Zakaria MR, Ullah F, Akil HM

Carbohydr Polym, 2016 Jan 20;136:1182-93.
PMID: 26572461 DOI: 10.1016/j.carbpol.2015.10.034

This study attempted to clarify the influence of a cross-linker, N,N-methylenebisacrylamide (MBA), and N-isopropylacrylamide (NIPAM) on the non-isothermal kinetic degradation, solid state and lifetime of hydrogels using the Flynn-Wall-Ozawa (F-W-O), Kissinger, and Coats-Redfern (C-Red) methods. The series of dual-responsive Cs-PNIPAM-MBA microgels were synthesized by soapless-emulsion free radical copolymerization in an aqueous medium at 70 °C. The thermal properties were investigated using thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) under nitrogen atmosphere. The apparent activation energy using the chosen Flynn-Wall-Ozawa and Kissinger methods showed that they fitted each other. Meanwhile, the type of solid state mechanism was determined using the Coats-Redfern method proposed for F1 (pure Cs) and F2 (Cs-PNIPAM-MBA hydrogel series) types, which comprise random nucleation with one nucleus reacting on individual particles, and random nucleation with two nuclei reacting on individual particles, respectively. On average, a higher Ea was attributed to the greater cross-linking density of the Cs hydrogel.
Mechanical and cytotoxicity properties of hybrid ceramics filled polyamide 12 filament feedstock for craniofacial bone reconstruction via fused deposition modelling

Abdullah AM, Rahim TNAT, Hamad WNFW, Mohamad D, Akil HM, Rajion ZA

Dent Mater, 2018 11;34(11):e309-e316.
PMID: 30268678 DOI: 10.1016/j.dental.2018.09.006

OBJECTIVE: To compare the mechanical and biological properties of newly developed hybrid ceramics filled and unfilled polyamide 12 (PA 12) for craniofacial reconstruction via a fused deposition modelling (FDM) framework.
METHODS: 15wt% of zirconia (ZrO2) as well as 30, 35, and 40wt% of beta-tricalcium phosphate (β-TCP) were compounded with PA 12, followed by the fabrication of filament feedstocks using a single screw extruder. The fabricated filament feedstocks were used to print the impact specimens. The melt flow rate, tensile properties of fabricated filament feedstocks, and 3D printed impact properties of the specimens were assessed using melt flow indexer, universal testing machine, and Izod pendulum tester, respectively. The microstructure of selected filament feedstocks and broken impact specimens were analysed using a field emission scanning electron microscope and universal testing machine. Human periodontal ligament fibroblast cells (HPdLF) were used to evaluate the cytotoxicity of the materials by (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromid) (MTT) assay.
RESULTS: Hybrid ceramics filled PA 12 indicated sufficient flowability for FDM 3D printing. The tensile strength of hybrid ceramics filled PA 12 filament feedstocks slightly reduced as compared to unfilled PA 12. However, the tensile modulus and impact strength of hybrid ceramics filled PA 12 increased by 8%-31% and 98%-181%, respectively. A significant increase was also detected in the cell viability of the developed composites at concentrations of 12.5, 25, 50 and 100mg/ml.
SIGNIFICANCE: The newly developed hybrid ceramics filled PA 12 filament feedstock with improved properties is suitable for an FDM-based 3D printer, which enables the creation of patient-specific craniofacial implant at a lower cost to serve low-income patients.
Enhancement of thermal, mechanical and physical properties of polyamide 12 composites via hybridization of ceramics for bone replacement

Abdullah AM, Mohamad D, Rahim TNAT, Akil HM, Rajion ZA

Mater Sci Eng C Mater Biol Appl, 2019 Jun;99:719-725.
PMID: 30889745 DOI: 10.1016/j.msec.2019.02.007

This study reports the influence of ZrO2/β-TCP hybridization on the thermal, mechanical, and physical properties of polyamide 12 composites to be suited for bone replacement. Amount of 15 wt% of nano-ZrO2 along with 5,10,15,20 and 25 wt% of micro-β-TCP was compounded with polyamide 12 via a twin-screw extruder. The hybrid ZrO2/β-TCP filled polyamide 12 exhibited higher thermal, mechanical and physical properties in comparison to unfilled polyamide 12 at certain filler loading; which is attributed to the homogenous dispersion of ZrO2/β-TCP fillers particle in polyamide 12 matrix. The hybrid ZrO2/β-TCP filled PA 12 demonstrated an increment of tensile strength by up to 1%, tensile modulus of 38%, flexural strength of 15%, flexural modulus of 45%, and surface roughness value of 93%, as compared to unfilled PA 12. With enhanced thermal, mechanical and physical properties, the newly developed hybrid ZrO2/β-TCP filled PA 12 could be potentially utilized for bone replacement.
Fulltext Coupled Oxides/LLDPE Composites for Textile Effluent Treatment: Effect of Neem and PVA Stabilization

Basiron N, Sreekantan S, Kang LJ, Akil HM, Mydin RBSMN

Polymers (Basel), 2020 Feb 09;12(2).
PMID: 32050485 DOI: 10.3390/polym12020394

The polyvinyl alcohol (PVA) and neem extract were grafted onto coupled oxides (3ZT-CO) via reflux process to stabilize the particles to form 3ZT-CO/PVA and 3ZT-CO/Neem. These were then incorporated into LLDPE by melt blending process to give LLDPE/3ZT-CO/PVA and LLDPE/3ZT-CO/Neem composites. The Neem and PVA stabilized particles showed high zeta potential and dispersed homogeneously in water. The stabilization process altered the shape of the particles due to plane growth along the (002) polar direction. The stabilizers acted as capping agents and initiated the one-dimensional growth. The alkyl chain groups from PVA increased the polarity of the LLDPE/3ZT-CO/PVA and played a dominant role in the water adsorption process to activate the photocatalytic activity. This was further enhanced by the homogeneous distribution of the particles and low degree of crystallinity (20.87%) of the LLDPE composites. LLDPE/3ZT-CO/PVA exhibited the highest photodegradation (93.95%), which was better than the non-stabilized particles. Therefore, the photocatalytic activity of a polymer composite can be enhanced by grafting PVA and neem onto couple oxides. The LLDPE/3ZT-CO/PVA composite was further used to treat textile effluent. The results showed the composite was able to remove dye color by 93.95% and to reduce biochemical oxygen demand (BOD) and chemical oxygen demand (COD) by 99.99%.
Synthesis and evaluation on pH- and temperature-responsive chitosan-p(MAA-co-NIPAM) hydrogels

Rasib SZM, Ahmad Z, Khan A, Akil HM, Othman MBH, Hamid ZAA, et al.

Int J Biol Macromol, 2018 Mar;108:367-375.
PMID: 29222015 DOI: 10.1016/j.ijbiomac.2017.12.021

In this study, chitosan-poly(methacrylic acid-co-N-isopropylacrylamide) [chitosan-p(MAA-co-NIPAM)] hydrogels were synthesized by emulsion polymerization. In order to be used as a carrier for drug delivery systems, the hydrogels had to be biocompatible, biodegradable and multi-responsive. The polymerization was performed by copolymerize MAA and NIPAM with chitosan polymer to produce a chitosan-based hydrogel. Due to instability during synthesis and complexity of components to produce the hydrogel, further study at different times of reaction is important to observe the synthesis process, the effect of end product on swelling behaviour and the most important is to find the best way to control the hydrogel synthesis in order to have an optimal swelling behaviour for drug release application. Studied by using Fourier transform infra-red (FTIR) spectroscopy found that, the synthesized was successfully produced stable chitosan-based hydrogel with PNIPAM continuously covered the outer surface of hydrogel which influenced much on the stability during synthesis. The chitosan and PMAA increased the zeta potential of the hydrogel and the chitosan capable to control shrinkage above human body temperature. The chitosan-p(MAA-co-NIPAM) hydrogels also responses to pH and temperature thus improved the ability to performance as a drug carrier.
Classification, processing, and applications of bioink and 3D bioprinting: A detailed review

Raees S, Ullah F, Javed F, Akil HM, Jadoon Khan M, Safdar M, et al.

Int J Biol Macromol, 2023 Mar 31;232:123476.
PMID: 36731696 DOI: 10.1016/j.ijbiomac.2023.123476

With the advancement in 3D bioprinting technology, cell culture methods can design 3D environments which are both, complex and physiologically relevant. The main component in 3D bioprinting, bioink, can be split into various categories depending on the criterion of categorization. Although the choice of bioink and bioprinting process will vary greatly depending on the application, general features such as material properties, biological interaction, gelation, and viscosity are always important to consider. The foundation of 3D bioprinting is the exact layer-by-layer implantation of biological elements, biochemicals, and living cells with the spatial control of the implantation of functional elements onto the biofabricated 3D structure. Three basic strategies underlie the 3D bioprinting process: autonomous self-assembly, micro tissue building blocks, and biomimicry or biomimetics. Tissue engineering can benefit from 3D bioprinting in many ways, but there are still numerous obstacles to overcome before functional tissues can be produced and used in clinical settings. A better comprehension of the physiological characteristics of bioink materials and a higher level of ability to reproduce the intricate biologically mimicked and physiologically relevant 3D structures would be a significant improvement for 3D bioprinting to overcome the limitations.