Browsing by Author "Mukhokosi, Emma Panzi"

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Atomic force microscopy in structural and functional studies of biomolecules
(Biophysical Reviews and Letters, 2025-10) Uzorka, Afam; Mukhokosi, Emma Panzi
Atomic force microscopy (AFM) has emerged as a cornerstone technology in molecular and cellular biophysics, offering nanometer-scale resolution under near-physiological conditions. Unlike electron microscopy (EM), AFM preserves native biomolecular states and enables simultaneous acquisition of topographical and mechanical data. This review synthesizes the principles, applications, methodological advances, and future directions of AFM in both structural and functional studies of biomolecules. Structural applications include high-resolution imaging of proteins, nucleic acids, and membrane systems, while functional investigations leverage single-molecule force spectroscopy (SMFS), binding interaction analysis, and mechanobiology assays. Methodological innovations such as high-speed AFM (HS-AFM), functionalized probes, and correlative multi-modal techniques have expanded AFM’s capacity to probe dynamic processes in real time. Despite challenges such as tip-induced artefacts, throughput limitations, and data interpretation complexities, emerging trends point toward AI-assisted image analysis, in-cell AFM, and integration with molecular simulations. Functionalized nanosensors and automated platforms promise to transform AFM from a specialized research instrument into a high-throughput, intelligent biophysical tool. By bridging the gap between structural detail and functional insight, AFM is poised to play a pivotal role in advancing our understanding of biomolecular mechanisms, disease pathology, and therapeutic development.
Co-sensitization effect of chlorophyll and anthocyanin on optical absorption properties and power conversion efficiency of dye-sensitized solar cells
(Springer, 2024-04) Mukhokosi, Emma Panzi; Mohammed, Tibenkana; Loyce, Namanya; Botha, Nandipha L.; Maaza, Maliki; Velauthapillai, Dhayalan
In this article, the chemical structure, optical absorption and photoluminescence properties of un/adsorbed dyes of hibiscus flower (H), pumpkin leaf (P), sweet potato leaf (S) and their composites (H: P & H: S) have been studied. The chemical structural properties revealed the O–H, C–C and C = O as the main anchoring functional groups. The optical absorption properties revealed two definite bands in between 450–500 nm and 600–680 nm wavelength for chlorophyll-based dyes and a peak at 526 nm for anthocyanin based dye extract. The composite dye extracts revealed optical absorption bands corresponding to chlorophyll and anthocyanin pigments with enhanced absorption of light. Five different solar cells based on H, P, S, H:P-3:1 and H:S-3:1 were developed and revealed an efficiency of ~ 0.08, 0.3, 0.5, 0.7 and ~ 1% respectively. The efficiency was reduced by half after 30 days. The composites had the highest power conversion efficiency due to more O–H, C–C and C = O binding sites on TiO2 nanoparticles, reduced rate of electron–hole pair recombination and a wide range of optical absorption. These studies suggest that co-pigmentation can be an alternative strategy to increasing the power conversion efficiency in DSSCs.
Green synthesis of hematite nano flakes and their application as a counter electrode in dye-sensitized solar cells
(Scientific Reports, 2025-06-05) Mukhokosi, Emma Panzi; Mushebo, Emmanuel; Nassejje, Stella; Botha, Nandipha L.; Velauthapillai, Dhayalan; Maaza, Malik
This study pioneers using hematite nanoflakes as a viable alternative to traditional platinum counter-electrodes in dye-sensitized solar cells (DSSCs), demonstrating its effectiveness for the first time. Besides such a novelty, the used hematite nanoflakes were bio-engineered using ginger extract as an effective chelating reducing agent. From the X-ray diffraction studies, it was observed that the sample annealed at 700 °C formed a highly crystalline α-Fe2O3, with a crystallite nano-scaled size of the order of 46.3 nm. The scanning electron microscopy investigations indicated a preferred layered nanoflakes morphology while the optical properties revealed a direct band gap of 2.30 eV. Using N-719 dye as a sensitizer on TiO2 photoanode and I−/I3− as electrolyte, the DSSC was fabricated. Such a cell exhibited significant DSSC responses, namely; a short circuit current density (JSC) of 7.0 mAcm−2, an open circuit voltage (VOC) of 389 mV, and a fill factor (FF) of 75.3% in addition to an efficiency (η) of 2.05%. Based on such a significant photo-conversion response using bio-engineered active counter electrodes, this study provides a cost-effective approach for synthesizing hematite NFs that have potential applications not only in DSSC but also in sensors, water splitting, and electrochemical devices.
Green synthesis of ZnO nanoparticles for DSSC photoanode : a joint experimental and density functional theory study
(Materials Research Express, 2025-09-29) Balabye, Stephen Emma; Mushebo, Emmanuel; Nasejje, Stella; Egor, Moses; Mukhokosi, Emma Panzi
Green synthesis, a biological method for nanoparticle preparation, has been suggested as a possible eco-friendly alternative to chemical and physical methods. In this study, we report on first principles calculations and the green synthesis of zinc oxide (ZnO) nanoparticles (NPs) from Erythrina abyssinica stem bark extract calcined under different temperatures (300-700 ℃) for application as a photoanode in dye sensitized solar cells (DSSCs). Synthesized ZnO NPs were subjected to characterization using X-Ray diffraction, Scanning Electron Microscopy, Energy Dispersive X-Ray spectroscopy, Ultraviolet–Visible spectroscopy and photoluminescence analysis. The analysis revealed that highly crystalline hexagonal ZnO NPs were formed at 700 ℃, with the nanospheres agglomeration into non-uniform distinct NPs with a band gap energy of 3.12 eV. The DSSC exhibited a short circuit current density (Jsc) of 56 µA cm-2, open circuit voltage (Voc) of 161 mV, a fill factor of 0.265, and a power conversion efficiency of 0.0024% using 100 mWcm-2 illumination. Density Functional Theory (DFT) calculations were performed on the structural, electronic, and dielectric properties of ZnO at the atomic level. The Projected Density of States (PDOS) analysis revealed that Zn-4s and O-2p orbitals contributed significantly to the conduction band minimum (CBM) and valence band maximum (VBM), respectively, and a direct band gap at Gamma in the electronic band structure. Dielectric function analysis revealed anisotropy in the refractive index and dielectric function, with noticeable transparency in the visible spectrum and strong absorption in the ultraviolet, making them potential candidates in a set of photoelectrochemical applications.
Structural, chemical, and mechanical properties of concrete developed from a binder composite of sugarcane bagasse ash and Portland cement
(Discover Materials, 2025-06-05) Nzugua, Michael Evans; Mukhokosi, Emma Panzi; Kinyera, Sam Obwoya
The East Africa Community (EAC) countries have immense sugarcane cane bagasse ash (SCBA) which remains unexploited as a supplementary-cementitious material (SCM). This study delved into using EAC SCBA as a pozzolan. SCBA investigated was collected from Kenya’s coastal area. Raw SCBA, processed SCBA, Portland cement (PC) and the developed concrete were characterised by various techniques to determine the surface morphology, chemical composition, structural properties and mineralogical composition. The raw SCBA was calcined at 600 °C then used to design the concrete mix. PC was replaced with SCBA from 0 to 30% in steps of 10%. The flexural and compressive strengths were determined in the hardened state after 28 days of concrete curing. The compressive and flexural strengths of the mix containing 20% SCBA were higher than the control mix by 9.65 and 6.51%, respectively. The microstructural properties of the developed concrete revealed dense particle distribution, indicating good micro/nanofiller effects of the interfacial transition zone (ITZ). The processed SCBA was found to meet class N and F of natural pozzolan as per ASTM C 618. This study suggests that the Kenya coastal SCBA can be used as a supplementary cementitious material.