Green synthesis of copper oxide (CuO) nanoparticles offers a sustainable alternative to conventional chemical methods that often involve toxic reagents and harsh conditions. This study investigates the use of Tithonia diversifolia, an invasive species in Sri Lanka, as a bioreductant for the eco-friendly fabrication of CuO nanoparticles. Using copper sulfate (CuSO₄·5H₂O) as a precursor, eight treatments were conducted by varying precursor concentration, temperature, and reaction time to determine optimal conditions. A visible color change in the reaction mixture initially indicated nanoparticle formation. Among all the conditions, treatment T4 (5 mM CuSO₄, 80 °C, 2 h) yielded the most favorable results in terms of stability, morphology, and crystallinity. UV-Vis spectroscopic analysis confirmed the synthesis, with absorbance peaks between 265 and 285 nm. FTIR analysis revealed organic functional groups and characteristic metal–oxygen vibrations in the fingerprint region (500–650 cm⁻¹), confirming formation. SEM imaging showed that particles were mainly spherical to polygonal, averaging 125–150 nm. However, dynamic light scattering showed larger diameters (~240 nm) due to surface capping agents. Zeta potential values ranged from −16.0 to −28.0 mV, indicating stability. XRD data revealed partial crystallinity with CuO-specific peaks. These findings support the potential of T. diversifolia in green nanoparticle synthesis, suggesting a low-cost, eco-conscious strategy for future applications.

The field of bio-nanotechnology has seen significant advancements in recent years, particularly in the synthesis and application of bio-nanoparticles (BNPs). This review focuses on the green synthesis of BNPs using biological entities such as plants, bacteria, fungi, and algae. The utilization of these organisms for nanoparticle synthesis offers an eco-friendly and sustainable alternative to conventional chemical and physical methods, which often involve toxic reagents and high energy consumption. Phytochemicals present in plant extracts, unique metabolic pathways, and biomolecules in bacteria and fungi, and the rich biochemical composition of algae facilitate the production of nanoparticles with diverse shapes and sizes. This review further explores the wide-ranging applications of BNPs in various fields like therapeutics, fuel cells, energy generation, and wastewater treatment. In therapeutics, BNPs have shown efficacy in antimicrobial, anti-inflammatory, antioxidant, and anticancer activities. In the energy sector, BNPs are being integrated into fuel cells and other energy generation systems like bio-diesel to improve efficiency and sustainability. Their catalytic properties and large surface area enhance the performance of these devices. Wastewater treatment is another critical area where BNPs are employed for the removal of heavy metals, organic pollutants, and microbial contaminants, offering a cost-effective and environmentally friendly solution to water purification. This comprehensive review highlights the potential of bio-nanoparticles synthesized through green methods. It highlights the need for further research to optimize synthesis processes, understand mechanisms of action, and expand the scope of their applications. BNPs can be utilized to address advantages and some of the pressing challenges in medicine, energy, and environmental sustainability, paving the way for innovative and sustainable technological advancements in future prospects.

Nanocellulose obtained from renewable and abundant biomass has garnered significant attention as a sustainable material with exceptional properties and diverse applications. This review explores the key aspects of nanocellulose, focusing on its extraction methods, applications, and future prospects. The synthesis of nanocellulose involves mechanical, chemical, and biological techniques, each uniquely modifying the cellulose structure to isolate cellulose nanocrystals (CNCs), cellulose nanofibers (CNFs), or bacterial nanocellulose (BNC). These methods provide tailored characteristics, enabling applications across a wide range of industries. Nanocellulose’s remarkable properties, including high mechanical strength, large surface area, thermal stability, and biodegradability, have propelled its use in packaging, electronics, biomedicine, and environmental remediation. It has shown immense potential in enhancing the mechanical performance of composites, improving water purification systems, and serving as a scaffold for tissue engineering and drug delivery. However, challenges related to large-scale production, functionalization, regulatory frameworks, and safety concerns persist, necessitating further research and innovation. This review emphasizes the need for sustainable production strategies and advanced functionalization techniques to harness nanocellulose’s full potential. As an eco-friendly, high-performance material, nanocellulose presents a promising avenue for addressing global sustainability challenges while offering transformative solutions for various industries.

Nanofluids, fluids with different suspended nanoparticles, have shown improved thermo-physical properties in recent research outputs, and they have emerged as promising alternatives for the industrial fluids used in numerous heat exchange applications. Much research has been conducted around the world to develop heat transfer fluids with optimum thermo-physical properties with the help of nanotechnology, especially in the 21st century. Following the latest research outcomes, nanofluids with base fluids of industrially used coolants, such as water, engine oil, transformer oil, electronic coolants, etc., have shown imposing thermo-physical properties compared to their base fluid. Identifying the nanofluids with high performances and lesser practical obstacles to be used as heat transfer fluids is vital. This paper reviews the thermo-physical property improvements of nanofluid properties, such as thermal conductivity, viscosity, density, specific heat capacity, and flash point, along with their theoretical models. Recent studies on using surfactants to improve the stability of nanofluids are also included in this review. The next part of the study reviews the latest research outputs on the thermo-physical properties of nanofluids in applications in engineering disciplines. Later, research on molecular dynamics simulations of nanofluids are discussed. As the final section, this paper presents Nanofluid research related to neural network modeling. Cumulatively, this paper presents a comprehensive review of recent nanofluids research, along with theoretical developments. This review is a cumulative study of the recent studies of nanofluid research in different disciplines. Most of the recent reviews focused on specific applications of nanofluids and do not cover the field from the basics of the nanofluids to their applications. However, this review covers all the aspects of the nanofluid field, along with several important engineering applications.

Aims: Stevia rebaudiana which is commonly known as sweet leaf herb is used to extract non caloric sweet steviol glycosides. Thus based on available reports about its chemical composition, biosynthesis of steviol glycosides, application, cultivation, and phytochemical screening an attempt has been made to review to Stevia rebaudiana in context of its medicinal and pharmaceutical importance. Methodology: Literature search have been done in the web using google scholar, PubMed as search platform. More than two-thirds of the references are within 15 years. Results: According to the literature search S. rebaudiana leaves contain non caloric steviol glycosides and pharmaceutically important other phytochemicals. Miccropropagation is the best propagation method to overcome difficulties in conventional propagation methods. Conclusion: It is concluded that in vitro cultures has potential to extract important phytochemicals used in various pharmaceutical, food (flavoring agents, food additives) and perfume industries.

The poor thermal and physical properties of conventional engine oils limit vehicle performance and durability. This research aims to investigate the effect of nanoparticles such as fullerene C₆₀, titanium dioxide (TiO₂), iron oxide (Fe₂O₃), and reduced graphene oxide (rGO) nanoparticles on 10W30 Mobil engine oil. In this study, the effect of nanoparticle concentrations at different mass fractions (0.01, 0.05, and 0.1) was examined within the temperature range 30–120 °C. The nanofluids were prepared using a two-step direct mixing method and thermal properties were measured using a LAMBDA thermal conductivity meter, which uses the transient hot wire method according to the ISO standards. Due to the low concentrations of the nanofluids, surfactants were not required at all, and the stability of the nanofluids was visually monitored over a period of four weeks. Accordingly, the largest improvement in thermal conductivity occurred with TiO₂/10W30 at a mass fraction of 0.1 wt.% at 80 °C, and the specific heat capacity improved due to Fe₂O₃/10W30 addition at a mass fraction of 0.1 at 70 °C; these were 5.8% and 14.4%, respectively, for the base oil. Thermal diffusivity remained largely unaffected by the addition of the nanoparticles, and fullerene C₆₀ showed no significant effect on any thermal property. It was concluded that the thermal properties of the engine oil were considerably enhanced by the added nanoparticles at different weight fractions and temperature values.