Zinc oxide nanoparticles (ZnONPs) are the top candidate in the field of biological applications because of their high surface area and excellent catalytic activities. In the present study, the cyanobacteria-mediated biosynthesis of zinc oxide NPs using Nostoc sp. extract as a stabilizing, chelating, and reducing agent is reported. ZnONPs were biologically synthesized using an eco-friendly and simple technique with a minimal reaction time and calcination temperature. Various methods, including X-ray diffraction (XRD), ultraviolet spectroscopy (UV), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) were used to characterize the biosynthesized zinc oxide NPs. XRD analysis depicted the crystalline form of zinc oxide NPs, and the Scherrer equation determined a mean crystalline size of ~28.21 nm. The SEM results reveal the spherical shape of the biosynthesized nanoparticles. Various functional groups were involved in the capping and stabilization of the zinc oxide NPs, which were confirmed by FTIR analysis. The zinc oxide NPs showed strong UV-vis absorption at 340 nm. Multiple in vitro biological applications showed significant therapeutic potential for zinc oxide NPs. Potential antimicrobial assays were reported for zinc oxide NPs via the disc-diffusion method and food poisoning method, respectively. All other activities mentioned below are described with the concentration and IC50 values. Biocompatibility with human erythrocytes and macrophages (IC50: 433 µg/mL, IC50 > 323 µg/mL) and cytotoxic properties using brine shrimps (IC50: 11.15 µg/mL) and Leishmania tropics (Amastigotes IC50: 43.14 µg mL⁻¹ and Promastigotes IC50: 14.02 µg mL⁻¹) were determined. Enzyme inhibition assays (protein kinase and alpha amylase) were performed and showed strong potential. Free radical scavenging tests showed strong antioxidant capacities. These results indicate that zinc oxide NPs synthesized by Nostoc sp. have strong biological applications and are promising candidates for clinical development.

Cadmium (Cd) and lead (Pb) are global environmental pollutants. In this study, Nostoc sp. MK-11 was used as an environmentally safe, economical, and efficient biosorbent for the removal of Cd and Pb ions from synthetic aqueous solutions. Nostoc sp. MK-11 was identified on a morphological and molecular basis using light microscopic, 16S rRNA sequences and phylogenetic analysis. Batch experiments were performed to determine the most significant factors for the removal of Cd and Pb ions from the synthetic aqueous solutions using dry Nostoc sp. MK1 biomass. The results indicated that the maximum biosorption of Pb and Cd ions was found under the conditions of 1 g of dry Nostoc sp. MK-11 biomass, 100 mg/L of initial metal concentrations, and 60 min contact time at pH 4 and 5 for Pb and Cd, respectively. Dry Nostoc sp. MK-11 biomass samples before and after biosorption were characterized using FTIR and SEM. A kinetic study showed that a pseudo second order kinetic model was well fitted rather than the pseudo first order. Three isotherm models Freundlich, Langmuir, and Temkin were used to explain the biosorption isotherms of metal ions by Nostoc sp. MK-11 dry biomass. Langmuir isotherm, which explains the existence of monolayer adsorption, fitted well to the biosorption process. Considering the Langmuir isotherm model, the maximum biosorption capacity (q_max) of Nostoc sp. MK-11 dry biomass was calculated as 75.757 and 83.963 mg g⁻¹ for Cd and Pb, respectively, which showed agreement with the obtained experimental values. Desorption investigations were carried out to evaluate the reusability of the biomass and the recovery of the metal ions. It was found that the desorption of Cd and Pb was above 90%. The dry biomass of Nostoc sp. MK-11 was proven to be efficient and cost-effective for removing Cd and especially Pb metal ions from the aqueous solutions, and the process is eco-friendly, feasible, and reliable.

The current study aimed to investigate the viability and characteristics of Scenedesmus sp. as an adsorbent system to remove lead (Pb) and cadmium (Cd) through an in vitro exposure to a metal solution. In batch sorption experiments, the effects of pH, contact time, initial concentration of metal ions, and sorbent dosage on the adsorption process were trialed. The ideal biosorption conditions for each of the two metals were recorded. The biosorption process was quick, and the equilibrium times for the above-mentioned metals were recorded as 90 and 60 min, with removal percentages of 85% and 83%, respectively. The point zero charge of algal biomass was 4.5, which indicates a negative charge on the surface of the biosorbent. The model-based assessment of the biosorption process was revealed to have followed pseudo-second-order kinetics. The adsorption isotherms for lead and cadmium achieved a best fit with the Langmuir model, with monolayer biosorption capacities of 102 and 128 mg g⁻¹, respectively. The desorption of both metals achieved more than 70% by using HCl. The FT-IR revealed the presence of hydroxyl and amine groups on the surface of the adsorbent that are involved in the biosorption process, and morphological changes were assessed by SEM. Hence, Scenedesmus sp. from a Himalayan provenance showed considerable promise as an alternate sorbent for the treatment of heavy-metal-contaminated wastewater.

Nanoparticles have emerged as a prominent area of research in recent times, and silver nanoparticles (AgNPs) synthesized via phyco-technology have gained significant attention due to their potential therapeutic applications. Nodularia haraviana, a unique and lesser-explored cyanobacterial strain, holds substantial promise as a novel candidate for synthesizing nanoparticles. This noticeable research gap underscores the novelty and untapped potential of Nodularia haraviana in applied nanotechnology. A range of analytical techniques, including UV-vis spectral analysis, dynamic light scattering spectroscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray powder diffraction, were used to investigate and characterize the AgNPs. Successful synthesis of AgNPs was confirmed through UV-visible spectroscopy, which showed a surface plasmon resonance peak at 428 nm. The crystalline size of AgNPs was 24.1 nm. Dynamic light scattering analysis revealed that silver oxide nanoparticles had 179.3 nm diameters and a negative surface charge of −18 mV. Comprehensive in vitro pharmacogenetic properties revealed that AgNPs have significant therapeutic potential. The antimicrobial properties of AgNPs were evaluated by determining the minimum inhibitory concentration against various microbial strains. Dose-dependent cytotoxicity assays were performed on Leishmanial promastigotes (IC₅₀: 18.71 μgmL⁻¹), amastigotes (IC50: 38.6 μgmL⁻¹), and brine shrimps (IC₅₀: 134.1 μg mL⁻¹) using various concentrations of AgNPs. The findings of this study revealed that AgNPs had significant antioxidant results (DPPH: 57.5%, TRP: 55.4%, TAC: 61%) and enzyme inhibition potential against protein kinase (ZOI: 17.11 mm) and alpha-amylase (25.3%). Furthermore, biocompatibility tests were performed against macrophages (IC₅₀: >395 μg mL⁻¹) and human RBCs (IC₅₀: 2124 μg mL⁻¹). This study showed that phyco-synthesized AgNPs were less toxic and could be used in multiple biological applications, including drug design and in the pharmaceutical and biomedical industries. This study offers valuable insights and paves the way for further advancements in AgNPs research.

Metallic nanoparticles have received a significant amount of reflection over a period of time, attributed to their electronic, specific surface area, and surface atom properties. The biogenic synthesis of iron oxide nanoparticles (FeONPs) is demonstrated in this study. The green synthesis of metallic nanoparticles (NPs) is acquiring considerable attention due to its environmental and economic superiorities over other methods. Leptolyngbya sp. L-2 extract was employed as a reducing agent, and iron chloride hexahydrate (FeCl₃·6H₂O) was used as a substrate for the biogenic synthesis of FeONPs. Different spectral methods were used for the characterization of the biosynthesized FeONPs, ultraviolet-visible (UV-Vis) spectroscopy gave a surface plasmon resonance (SPR) peak of FeONPs at 300 nm; Fourier transform infrared (FTIR) spectral analysis was conducted to identify the functional groups responsible for both the stability and synthesis of FeONPs. The morphology of the FeONPs was investigated using scanning electron microscopy (SEM), which shows a nearly spherical shape, and an X-ray diffraction (XRD) study demonstrated their crystalline nature with a calculated crystallinity size of 23 nm. The zeta potential (ZP) and dynamic light scattering (DLS) measurements of FeONPs revealed values of −8.50 mV, suggesting appropriate physical stability. Comprehensive in-vitro pharmacogenetic properties revealed that FeONPs have significant therapeutic potential. FeONPs have been reported to have potential antibacterial and antifungal properties. Dose-dependent cytotoxic activity was shown against Leishmania tropica promastigotes (IC50: 10.73 µg/mL) and amastigotes (IC50: 16.98 µg/mL) using various concentrations of FeONPs. The cytotoxic potential was also investigated using brine shrimps, and their IC50 value was determined to be 34.19 µg/mL. FeONPs showed significant antioxidant results (DPPH: 54.7%, TRP: 49.2%, TAC: 44.5%), protein kinase (IC50: 96.23 µg/mL), and alpha amylase (IC50: 3745 µg/mL). The biosafety of FeONPs was validated by biocompatibility tests using macrophages (IC50: 918.1 µg/mL) and red blood cells (IC50: 2921 µg/mL). In conclusion, biogenic FeONPs have shown potential biomedical properties and should be the focus of more studies to increase their nano-pharmacological significance for biological applications.

Industrialization, urbanization, and natural processes have potentially accelerated the pace and level of heavy metals in the aquatic environment. Recently, modern strategies for heavy metal treatment in wastewater have received the specific attention of the scientific community. The present study aimed to assess the amorphous biomass of Desmodesmus sp. as a low-cost adsorbent to remove the cadmium (Cd) and lead (Pb) from aqueous solutions. It involved the optimization of pH, contact time, initial concentration of metal ions, and the dosage of biosorbent. Data collation revealed that an optimum contact time for both metals was 60 min, with an adsorption capacity of 63% for Cd and 66% for Pb. Different models were applied to the equilibrium data. The pseudo 2nd order described the best adsorption of Cd and Pb. The equilibrium data were computed with various isotherms. Langmuir isotherms better suit the adsorption of the above-mentioned metals. Hence, the maximum adsorption capacity of Desmodesmus sp. for Cd and Pb was 64.1 and 62.5 mg/g, respectively. The mechanism of biosorption was validated through a comparative FT-IR and Scanning Electron Microscopy of raw and metal-loaded algal biomass based on cell morphological changes. In order to study the reusability of adsorbent, adsorption-desorption of Cd and Pb ions was repeated three times using HCl. These results did not noticeably change in adsorption capacity during the three cycles. Using HCl (0.1 M), desorption of both metals was achieved up to 90% in three cycles. This work presented a long-term bioremediation approach for heavy metal pollutants in wastewater. This research could be seen as an interdisciplinary approach to large-scale heavy metal remediation. In addition, growing microalgae in wastewater produces animal feed and biodiesel. When compared to other conventional methods for environmental remediation and the manufacture of valuable products, the use of microalgae is a more efficient and cost-effective method.