Journal Articles

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Biobased Biodegradable Polybutylene Succinate Polymers and Composites: Synthesis, Structure Properties and Applications—A Review
(2025) Makgwane, Peter R; Muniyasamy, Sudhakar; Hlekelele, Lerato; Swanepoel, Andri; Sypu, Venkata S; Mdlalose, Lindani M; Naidoo, Saloshee; Cele, Zamani; Maity, Arjun; Balogun, Mohammed O; Botlhoko, OJ
The materialization of polybutylene succinate (PBS) belongs to the family of polyesters which are degradable and biodegradable, their biodegradability properties have attracted enormous interest for product development towards different polymer-based applications. Besides its biodegradability, PBS can be derived from petroleum and biobased monomers. At the same time, the latter is the driving factor for its growing interest in bioplastics for fully green and sustainable biobased-derived polymer products. The processes and techniques presented herein, are based on the production of biobased succinic acid monomer to PBS. However, the counterpart biobased monomer 1,4-butanediol (1,4-BDO) production has not been commercially demonstrated. This review discusses the progress in state-of-the-art developments in the synthesis strategies of PBS, its copolymers, and composites with the view to improve molecular weight, thermal, and mechanical properties. It further analyzes the different strategies to synthesize modified PBS polymer composites from organic and inorganic nanofillers to enhance their chemical, thermal, stability and mechanical structural properties. Importantly, the review highlights the progress in the applications of PBS copolymers and composites with tailored structure-designed properties for specific sectors such as packaging films, biomedical and drug release, fire retardants, and agricultural products. The structure-functional performance characteristics of these developments in the PBS, copolymers, and composites are highlighted to provide baseline insights for future developments in engineering the specific applications, and structural interface PBS composites with enhanced structure-functional performance properties.
Carboxy-PEG-thiol functionalized gold nanoparticle conjugates for the detection of SARS-CoV-2: Detection tools and analytical method development
(2024-12) Hlekelele, Lerato; Setshedi, Katlego Z; Mandiwana, Vusani; Kalombo, Lonji; Lemmer, Yolandy; Chauke, Chauke P; Maity, Arjun
Addressing the need for accessible SARS-CoV-2 testing, carboxy-PEG 12-thiol functionalized gold nanoparticles conjugates were developed for rapid point-of-care (POC) detection against SARS-CoV-2 spike protein, pseudo-SARS-CoV-2, and authentic Beta SARS-CoV-2 virus particles. These conjugates leverage gold nanoparticles (AuNPs) as signal transducers, cross-linked to either angiotensin-converting enzyme 2 (ACE2) or SARS-CoV-2 spike protein receptor-binding domain (RBD) antibodies as bioreceptors and showed a distinct color shift from pink to blue. To assess their POC feasibility, the conjugates were integrated into facemasks and breathalyzers, wherein aerosolized SARS-CoV-2 antigens were successfully detected, producing a color change within 10 and 30 minutes for the breathalyzer and facemask prototypes, respectively. Furthermore, we explored quantitative analysis using varying concentrations of SARS-CoV-2 spike protein. Both conjugates demonstrated a linear relationship between blue color intensity and virus concentration, with linear ranges of 0.08–0.6 ng/mL and 0.04–0.5 ng/mL, respectively. Low limits of detection and quantification were also achieved. They exhibited specificity, responding solely to SARS-CoV-2 even in complex matrices containing diverse proteins, including the SARS-CoV-1 spike protein. Precision tests yielded coefficient of variations below 2 %, showcasing their remarkable reproducibility. This work presents a promising approach for rapid, sensitive, and specific POC detection of SARS-CoV-2 paving the way for improved pandemic response and management.
Chitosan coating loaded with spearmint essential oil nanoemulsion for antifungal protection in soft citrus (Citrus reticulata) fruits
(2025-01) Maswanganye, LTC; Pillai, Sreejarani K; Sivakumar, D
In this study, chitosan (CH) was loaded with spearmint (S) essential oil nanoemulsion (EO) to provide antifungal properties during the postharvest storage of soft citrus fruits. (S)-EO (2%) nanoemulsion–CH (0.8%) coatings inhibited 100% of Penicillium italicum and Penicillium digitatum radial mycelial growth and spore germination in vitro. The (S)EO(2%) nanoemulsion–CH coating (0.8%) enhanced the antifungal activity by achieving 100% inhibition of P. digitatum in soft citrus cultivars ‘Nova’ and ‘Tango’ compared to the control in vivo. However, P. italicum decay was reduced to 33% and 18% in ‘Nova’ and ‘Tango’ soft citrus compared to the control. The (S)-EO (2%)-CH nanoemulsion coating system prepared by high shear homogenization showed a particle size of 252.3 nm and zeta potential of +21.6 mV, indicating changes in molecular interactions and structural reorganization between EO and CH. The polydispersity index values indicated a stable system. pH remained acidic, antifungal activity was favored, and the incorporation of the EO nanoemulsion improved the thermal stability of the CH coating. The optical properties showed less transparency and more opacity. Despite cultivar differences affecting host specificity, the study recommends using a 2% (S)EO nanoemulsion–CH (0.8%) coating instead of synthetic chemicals to extend citrus fruit storage life.
Development and evaluation of Poly(Lactic-Co-Glycolic Acid) encapsulated betulinic acid nanocarrier for improved anti-tumor efficacy
(2024-12) Selepe, Cyril T; Dhlamini, Khanyisile S; Tshweu, Lesego L; Kwezi, Lusisizwe; Ramalapa, Bathabile E; Ray, Suprakas S
Betulinic acid (BA) is a promising natural anti-tumor agent renowned for its activity against various tumor cell types. Despite its favorable profile of low cytotoxicity to normal cells, BA’s inherent hydrophobic nature and relatively short systematic half-life impose hurdles for clinical application. This study introduces a strategy to surmount these obstacles by developing a drug delivery system employing poly(lactic-co-glycolic acid) (PLGA)-encapsulated BA nanoparticles (PLGA-BA NPs). Rigorous characterization techniques such as dynamic light scattering (DLS), x-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses are employed to confirm the integrity of the drug within the nanocarriers. The PLGA-BA NPs demonstrated a mean particle size of 196 ± 6.80 nm. XRD analysis demonstrated the amorphous state of the PLGA-BA formulation, a characteristic vital for sustained drug release and enhanced bioavailability. The PLGA-BA NPs exhibited spherical morphology with encapsulation and loading efficiency of 83 ± 9.24% and 7.0 ± 0.4%, respectively, highlighting efficient encapsulation of the drug within the PLGA NPs. In vitro, cytotoxicity assessments demonstrated enhanced anti-proliferative efficacy against breast and lung tumor cells when utilizing PLGA-BA NPs in comparison to free BA. This research underlines the potential of employing the developed PLGA-based nanocarrier to optimize the therapeutic efficacy of BA.
Localized surface plasmon resonance optical biosensor for simple detection of deoxyribonucleic acid mismatches
(2024) Lugongolo, Masixole Y; Ombinda-Lemboumba, Saturnin; Hlekelele, Lerato; Nyokana, Nontsikelelo; Mthunzi-Kufa, Patience
Optical biosensors are optical technologies that evaluate changes in the refractive index as they monitor non-covalent molecular interactions in real time. These make use of unsophisticated, label-free analytical approaches, which do not require dyes to produce a visible signal. In this study, the efficiency of localized surface plasmon resonance (LSPR) biosensor in detecting a single nucleotide mismatch in deoxyribonucleic acid is examined. The detection is based on the hybridization of a target DNA at 100 ng μL−1 with a complementary biotinylated probe as well as a partially complementary biotinylated with one nucleotide mismatch probe on a gold-coated surface. Both probes are used at a concentration of 0.1 μm. The LSPR exhibited sensitivity by differentiating sample M+ from sample C+ through varying transmission intensities of 0.28 and 0.26 μA, respectively. Based on these findings, this approach demonstrates a great potential due to its ability to distinguish samples that differ with a single base pair, and its efficiency will be explored in the development of a point-of-care device as a simpler and cost-effective approach for detection of various biologically and medically significant mutations such as antimicrobial resistance mutations. More work is underway to determine the robustness of the LSPR biosensor using the biotin–neutravidin approach.
Plant-derived natural products and their nano transformation: A sustainable option towards desert locust infestations
(2024-11) Mangundu, P; Makaudi, R; Paumo, HK; Ramalapa, Bathabile E; Tshweu, Lesego L; Raleie, N; Katata-Seru, L
The desert locust has been recognized as the most devastating migratory pest in the world. Swarms of this pest have been threatening vast regions of pastures and crops in Africa, Middle East, and South Asia. The biological management of expanding swarms has become a strategy of particular interest due to environmental awareness and economic issues associated with chemical pesticides. The present review aims to explore the latest updates and information about pesticidal plants that are distributed across Africa. Searches on Web of Science, Google Scholar, PubMed, and Scopus databases from 2013–2024 revealed a total of 22 plant species probed for insecticidal activities against desert locusts. The formulation, active ingredients, and biological effects of essential oils and other extracts from these plants are presented. Despite the promising antiwww.chemistryopen.org [a] [a] Bathabile Ramalapa, [b] insecticidal effects of the plant extracts and compounds, issues related to their solubility and instability under environmental conditions have been observed. To address such major quality defects, methods for the encapsulation of plant natural products within nanostructures are detailed. Given the presence of bioactive compounds with nucleophiles bearing functional groups, the reported plant extracts have been exploited to fabricate metal nanoparticles with inherent insecticidal activities. In this paper, a holistic overview of prepared phytochemical-coated metal nanopesticides is also presented. In summary, this study offers insights into the integration of nanoformulated natural resources as a more sustainable option to control desert locust invasions.

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