Publications by authors named "Mahmood H Akhtar"

The development of organic dyes with emission peaks in the second near-infrared window (NIR-II 1000-1700 nm) is highly desirable for imaging and imaging-guided phototheranostics. However, the lack of appropriate molecular frameworks and the challenges associated with complex synthesis critically hinder the development of new candidate fluorophores. J-Aggregation is considered as a smart and straightforward way to construct such a therapeutic agent with NIR-II fluorescence imaging properties.

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Ferroptosis is a form of programmed cell death and plays an important role in many diseases. Dihydroorotate dehydrogenase (DHODH) and glutathione peroxidase 4 (GPX4) play major roles in cell resistance to ferroptosis. Therefore, inactivation of these proteins provides an excellent opportunity for efficient ferroptosis-based synergistic cancer therapy.

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Fluorescence-based visual assays have sparked tremendous attention in on-site detection due to their obvious color gradient changes and high sensitivity. In this study, a novel emission wavelength shift-based visual sensing platform is constructed to detect glucose based on the oxidation of Rhodamine B (RhB). MnO nanosheets (MnO NS) with strong oxidizing properties were introduced to oxidize RhB, which resulted in a blue shift in the emission wavelength, and a visual color changed of the fluorescence from orange-red to green.

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In this work, an electrochemical immunosensor based on black phosphorus nanosheets (BPNS)/poly(allylamine hydrochloride) (PAH) nanocomposite modified glassy carbon electrode was developed for the detection of ovarian cancer biomarker HE4. PAH has been applied to retain BPNS in its original honeycomb structure and to anchor biomolecules electrostatically on the transducer surface. The as synthesized nanocomposite was characterized by zeta potential analysis, scanning electron microscopy, x-ray photoelectron spectroscopy, transmission electron microscopy, high-resolution transmission electron microscopy.

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Viral infections have been proven a severe threat to human beings, and the pandemic of Coronavirus Disease 2019 (COVID-19) has become a societal health concern, including mental distress and morbidity. Therefore, the early diagnosis and differentiation of viral infections are the prerequisite for curbing the local and global spread of viruses. To this end, carbon nanotubes (CNTs) based virus detection strategies are developed that provide feasible alternatives to conventional diagnostic techniques.

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Octahedral SrMoO nanoparticles (NPs) with a high degree of crystallinity and controlled size (250-350 nm) were synthesized for the first time by employing a facile hydrothermal method. The prepared NPs were composited with a carboxyl group bearing conducting polymer (2,2:5,2-terthiophene-3-(-benzoic acid, TBA)) to attain a stable sensor probe (pTBA/SrMoO) which was analyzed using various surface analysis methods. The catalytic performance of the composite electrode was explored as an oxidation catalyst for biological molecules through anchoring on the conducting polymer layer, which functioned as a matrix to enhance the stability and selectivity of the sensor probe.

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This paper proposes a multi-scale analysis technique based on the micromechanics of failure (MMF) to predict and investigate the damage progression and ultimate strength at failure of laminated composites. A lamina's representative volume element (RVE) is developed to predict and calculate constituent stresses. Damages that occurred in the constituents are calculated using separate failure criteria for both fiber and matrix.

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Herein, we synthesized hollow cubic caves of CuO (HC) and wrapped it with N-rich graphitic C (NC), derived from a novel biogenic mixture composed of dopamine (DA) and purine. The synthesized NC wrapped HC (NC@HC) sensor shows enhanced electrocatalytic efficacy compared to unwrapped CuO with shapes including HC, sponge (SP), cabbage (CB), and solid icy cubes (SC). The shape and composition of synthesized materials were confirmed through field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS), whereas interfacial surface energy was calculated through contact angle measurement.

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Over the past few years, surface pressure measurement has fundamental importance in many areas, particularly, aerodynamic research. Conventional methods involve pressure taps, but due to the nature of these pressure taps, only pressure information of isolated points on model surface is available, which limit their applications in aerodynamics studies. Recently the newly developed approach, pressure sensitive paint (PSP) has revolutionized such pressure measurements and various PSP materials have been developed for aerodynamics research.

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A robust amperometric sensor was developed for the lactate detection in the extracellular matrix of cancer cells. The sensor was fabricated by separately immobilizing nicotinamide adenine dinucleotide (NAD) onto a carboxylic acid group and lactate dehydrogenase (LDH) onto an amine group of bi-functionalized conducting polymer (poly 3-(((2,2':5',2″-terthiophen)-3'-yl)-5-aminobenzoic acid (pTTABA)) composited with N, S-doped porous carbon. Morphological features of the composite layer and sensor performance were investigated using FE-SEM, XPS, and electrochemical methods.

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Lung cancer is undoubtedly one of the most serious health issues of the 21 st century. It is the second leading cause of cancer-related deaths in both men and women worldwide, accounting for about 1.5 million deaths annually.

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Brain-derived neurotrophic factor (BDNF) was detected in the extracellular matrix of neuronal cells using a dual probe immunosensor (DPI), where one of them was used as a working and another bioconjugate loading probe. The working probe was fabricated by covalently immobilizing capture anti-BDNF (Cap Ab) on the gold nanoparticles (AuNPs)/conducting polymer composite layer. The bioconjugate probe was modified by drop casting a bioconjugate particles composed of conducting polymer self-assembled AuNPs, immobilized with detection anti-BDNF (Det Ab) and toluidine blue O (TBO).

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The analytical performance of the multi enzymes loaded single electrode sensor (SES) and dual electrode sensor (DES) was compared for the detection of adenosine and metabolites. The SES was fabricated by covalent binding of tri-enzymes, adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP), and xanthine oxidase (XO) along with hydrazine (Hyd) onto a functionalized conducting polymer [2,2:5,2-terthiophene-3-(p-benzoic acid)] (pTTBA). The enzyme reaction electrode in DES was fabricated by covalent binding of ADA and PNP onto pTTBA coated on Au nanoparticles.

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A microfluidic structured-dual electrodes sensor comprising of a pair of screen printed carbon electrodes was fabricated to detect acetylcholine, where one of them was used for an enzyme reaction and another for a detection electrode. The former was coated with gold nanoparticles and the latter with a porous gold layer, followed by electropolymerization of 2, 2:5,2-terthiophene-3-(p-benzoic acid) (pTTBA) on both the electrodes. Then, acetylcholinesterase was covalently attached onto the reaction electrode, and hydrazine and choline oxidase were co-immobilized on the detection electrode.

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A robust amperometric sensor for β-nicotinamide adenine dinucleotide (NADH) detection was developed through the organic complex formation with ethylenediaminetetraacetic acid (EDTA) bonded on the polyethylenimine (PEI)/activated graphene oxide (AGO) layer. The EDTA immobilized sensor probe (GCE/AGO/PEI-EDTA) revealed a catalytic property towards NADH oxidation that allows for the highly sensitive electrochemical detection of NADH at a low oxidation potential. Surface characterization demonstrated that the negatively charged AGO acted as nanofillers in the positively charged PEI matrix through the charge interaction.

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A highly sensitive amperometric sensor has been studied for selective monitoring of K(+)-induced dopamine released from dopaminergic cells (PC12) which is based on an EDTA immobilized-poly(1,5-diaminonaphthalne) (poly-DAN) layer comprising graphene oxide (GO) and gold nanoparticles (GO/AuNPs). The integration of a negatively charged probe molecule on the poly-DAN/GO/AuNPs nanohybrid attained the signal enhancement to discriminate dopamine (DA) molecules from foreign species by catalytic effect and surface charge, and hydrogen bonding-based interactions with a probe molecule. The sensor performance and morphology were investigated using voltammetry, impedance spectrometry, SEM, and XPS.

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