Browsing by Author "Bangash, Mohammed"

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    A comparative study of electrochemical stability and biocompatibility of TiN Nanowires and thin films for neural-electrode application
    (Elsevier, 2024-06-02) Sait, Roaa; Govindarajan, S.; Hussein, Deema; Alhowity, Alazouf; Baeesa, Saleh; Bangash, Mohammed; Abuzenadah, Adel; Cross, Richard
    Neural-electrode devices with adequate charge injection capacity, long operating lifetime and excellent biocompatibility with interfaced tissues are essential to treat chronic neurological disorders. The device’s efficiency hinges on the electrochemical properties of the electrode material, prompting extensive research on diverse material surfaces. Here, we investigate the electrochemical stability and biocompatibility of titanium nitride (TiN) nanowires (NWs) synthesized previously through the novel plasma enhanced chemical vapor deposition (PECVD) utilizing lower temperature as compared to conventional methods. These TiN-NWs were compared with TiN thin films, shedding light on their respective performances. TiN-NWs electrode revealed far superior electrochemical stability over 1000 cycles, achieving a capacitance retention of 93% as compared to 68% to that of TiN film electrode, under ambient conditions with dissolved oxygen. Moreover, our in-vitro cell culture spanning 20 days exhibited excellent biocompatibility for both substrates. Interestingly, cell distribution on the NWs appeared more dispersed with fewer clusters, potentially facilitating controlled electrical stimulation. These findings not only highlights the potential use of TiN-NWs for chronic stimulation of neurons, but also shows that surface morphology has a potential effect in minimising surface oxidation and improving electrochemial performance of the material.
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    The anterior gradient homologue 2 (AGR2) co‑localises with the glucose‑regulated protein 78 (GRP78) in cancer stem cells, and is critical for the survival and drug resistance of recurrent glioblastoma: in situ and in vitro analyses
    (Springer, 2022-12-08) Hussein, Deema; Alsereihi, Reem; Salwati, Abdulla Ahmed A; Algehani, Rinad; Alhowity, Alazouf; Al‑Hejin, Ahmed M; Schulten, Hans‑Juergen; Baeesa, Saleh; Bangash, Mohammed; Alghamdi, Fahad; Cross, Richard; Al Zughaibi, Torki; Saka, Mohamad; Chaudhary, Adeel; Abuzenadah, Adel
    Background: Glioblastomas (GBs) are characterised as one of the most aggressive primary central nervous system tumours (CNSTs). Single-cell sequencing analysis identified the presence of a highly heterogeneous population of cancer stem cells (CSCs). The proteins anterior gradient homologue 2 (AGR2) and glucose-regulated protein 78 (GRP78) are known to play critical roles in regulating unfolded protein response (UPR) machinery. The UPR machinery influences cell survival, migration, invasion and drug resistance. Hence, we investigated the role of AGR2 in drug-resistant recurrent glioblastoma cells. Methods: Immunofluorescence, biological assessments and whole exome sequencing analyses were completed under in situ and in vitro conditions. Cells were treated with CNSTs clinical/preclinical drugs taxol, cisplatin, irinotecan, MCK8866, etoposide, and temozolomide, then resistant cells were analysed for the expression of AGR2. AGR2 was repressed using single and double siRNA transfections and combined with either temozolomide or irinotecan. Results: Genomic and biological characterisations of the AGR2-expressed Jed66_GB and Jed41_GB recurrent glioblastoma tissues and cell lines showed features consistent with glioblastoma. Immunofluorescence data indicated that AGR2 co-localised with the UPR marker GRP78 in both the tissue and their corresponding primary cell lines. AGR2 and GRP78 were highly expressed in glioblastoma CSCs. Following treatment with the aforementioned drugs, all drug-surviving cells showed high expression of AGR2. Prolonged siRNA repression of a particular region in AGR2 exon 2 reduced AGR2 protein expression and led to lower cell densities in both cell lines. Co-treatments using AGR2 exon 2B siRNA in conjunction with temozolomide or irinotecan had partially synergistic effects. The slight reduction of AGR2 expression increased nuclear Caspase-3 activation in both cell lines and caused multinucleation in the Jed66_GB cell line. Conclusions: AGR2 is highly expressed in UPR-active CSCs and drug-resistant GB cells, and its repression leads to apoptosis, via multiple pathways.
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    Electrochemical Performance of Biocompatible TiC Films Deposited through Nonreactive RF Magnetron Sputtering for Neural Interfacing
    (ACS, 2023-12-14) Sait, Roaa; Al-Jawhari, Hala; Ganash, Aisha; Wustoni, Shofarul; Chen, Long; Nejib Hedhili, Mohammed; Wehbe, Nimer; Hussein, Deema; Alhowity, Alazouf; Baeesa, Saleh; Bangash, Mohammed; Abuzenadah, Adel; Inal, Sahika; Cross, Richard
    The efficacy of neural electrode stimulation and recording hinges significantly on the choice of a neural electrode interface material. Transition metal carbides (TMCs), particularly titanium carbide (TiC), have demonstrated exceptional chemical stability and high electrical conductivity. Yet, the fabrication of TiC thin films and their potential application as neural electrode interfaces remains relatively unexplored. Herein, we present a systematic examination of TiC thin films synthesized through nonreactive radio frequency (RF) magnetron sputtering. TiC films were optimized toward high areal capacitance, low impedance, and stable electrochemical cyclability. We varied the RF power and deposition pressure to pinpoint the optimal properties, focusing on the deposition rate, surface roughness, crystallinity, and elemental composition to achieve high areal capacitance and low impedance. The best-performing TiC film showed an areal capacitance of 475 μF/cm2 with a capacitance retention of 93% after 5000 cycles. In addition, the electrochemical performance of the optimum film under varying scanning rates demonstrated a stable electrochemical performance even under dynamic and fast-changing stimulation conditions. Furthermore, the in vitro cell culture for 3 weeks revealed excellent biocompatibility, promoting cell growth compared with a control substrate. This work presents a novel contribution, highlighting the potential of sputtered TiC thin films as robust neural electrode interface materials.