This review presents a comprehensive and critical analysis of green algae-based NPs and their cutting-edge applications in advancing SDGs. While previous reviews have explored algal biotechnology or green synthesis of NPs, this work uniquely integrates these domains by focusing on how algae-derived NPs address key sustainability challenges such as clean energy, environmental remediation, and healthcare while aligning with specific SDG targets. The novelty lies in a systematic evaluation of algae-mediated NP synthesis mechanisms, emphasizing their eco-friendly advantages over conventional methods, forward-looking discussion on the role of algal NPs in cross-disciplinary SDG applications and identifying underexplored synergies between algal nanotechnology and circular bioeconomy principles. By bridging gaps between nanotechnology, sustainability science, and algal research, this review offers a timely roadmap for harnessing algae-based NPs as transformative tools for global sustainable development.

The rising demand for sustainable nanomaterials necessitates alternatives to laboratory-grown synthetic nanoparticles, which often involve toxic reagents and energy-intensive processes. Green algae, with their rapid growth, carbon sequestration potential, and metal-accumulating properties, provide an ideal platform for eco-friendly NP synthesis. This review is motivated by the urgent need to align emerging biogenic nanomaterials with the SDG framework, offering scalable solutions to environmental and societal challenges while minimizing ecological footprints.

Green algae are of two primary groups: microscopic and larger green algae, adapted to their surroundings. Microscopic green algae are primarily grown in freshwater environments and are unicellular in nature, while macro green algae are multicellular marine plant-like organisms (Deglint et al., 2019). It is currently common practice to biosynthesize several metal oxides, bimetallic, and monometallic nanoparticles (NPs) from green algae. As of now, about 20 different classes of microgreen algae are used in the production of AgNPs. Pithophoraoedogonia, Chlorococcumhumicola, C. vulgaris, C. reinhardtii, and Enteromorpha flexuosa produce extracellular AgNPs with different geometrical features (Jena et al., 2014; Yousefzadi et al., 2014). Several strains of green macroalgae have been completely utilized in the manufacturing of metallic nanoparticles recently. Thebeneficial green macroalgae species, Ulva fasciata, was utilized to generate nano-scale silver colloids. The antibacterial qualities of these colloids were then assessed by adapting them to cotton fabric (Madhiyazhagan et al., 2017). There are several industrial, medical, and biotechnological uses for micro green algae, being a member of the Cladophorales order. Numerous important components, including alkaloids, phenols, flavonoids, carbohydrates, and functional groups, are abundant in them and may function as both alleviating and reducing agents around the micro-mediated production of nanoparticles (Yousefzadi et al., 2014). Table 1 describes the algal-mediated synthesis of metal nanoparticles using different reagents, highlighting the algal species employed, type of algae, metal precursors, bio-reducing/capping biomolecules, and their associated applications, along with recent literature references.

A diagrammatic representationof the biosynthesis of Ag NPs by Shyalina has been given in Figure 1.

Morphological features and size distribution are crucial parameters for studying bio-synthesized nanoparticles and their applications. The scanning electron microscope reveals the topographyof spirulina-mediated TiO₂ nanoparticles, which are circular in shape with an average particle size of 55 ± 15 nm, as shown in Figure 2.

By incubating Ulva intestinalis and Rhizoclonium fontinale algae in chloroauric acid for 72 h at 20 °C, AuNPs are produced intracellularly. The biosynthesis of AuNPs is indicated by a discernible purple colour shift of the thallus from green. Colour alteration could not be observed when the gold metal solution was developed with biological material, proving that no metabolites or intracellular enzymes were connected to the bio-reduction process. Among the most beneficial green seaweed species, Ulva fasciata was accustomed to produce nano-sized silver colloids, which were then applied to cotton fabric with and without citric acid to test their antimicrobial effectiveness (El-Rafie et al., 2013). In an alternative experiment, the silica gel suspension that contained Klebsormidium flaccidum demonstrated a visible purple colour shift in the chloroplast from green, indicating the ability of the cells to reduce the gold precursor (chloroauric acid). The existence of reduced gold precursor salt by the NADPH-dependent reductase enzyme or NADPH was furthersubstantiated by TEM investigation, that revealed dark-coloured patches within the thylakoid membrane (Sicard et al., 2010). Similarly, the algal cell wall of Tetraselmiskochinensiswas shown to synthesize AuNPs intracellularly. The non-existence of the creation of substances outside the cell was unequivocally confirmed by UV-visible spectroscopy. The cytoplasmic region did not contain as many AuNPs as the vicinity of the cell wall, which is apparently due to bioactive moieties that cause bio-reduction (Senapati et al., 2012).

Various methods, including supernatant-based non-cell culture medium and cell organic material extracts, can be employed for the outside cell production of nanobiomaterials by algae. A vast majority of micro green algae species, including Pithophora oedogonia (cuboid and hexangular, 24–55 nm), Chlorococcum humicola (globular, 16 nm), Chlorella vulgaris (trilateral, 28 nm), C. reinhardtii (quadrate and ring, 1–15 nm), and Enteromorpha flexuosa (disc-shaped, 15 nm), are used to generate AgNPs extracellularly (Xie et al., 2007; Barwal et al., 2011; Jena et al., 2014; Yousefzadi et al., 2014). Much research has been done recently on the green microalgae-mediated production of AuNPs, which is similar to AgNPs, as shown in Table 2. One of the most extensively used species of microalgae, Pithophora crispa from higher altitudes, reduces the precursor salt of chloroauric acid to produce AuNPs through the assistance of extracellular and intracellular proteins and peptides (Xie et al., 2007). Another significant species of kelp, Chaetomorpha linum, is known for its environment-derived function in controlling the availability of food components in its dwelling space. AgNPsare synthesized by prompting the reduction of silver ions (Ag⁺) to Ag⁰ in the extracellular environment with the aid of peptides, flavonoids, and terpenoids (Priyadharshini et al., 2014). In addition to AgNPs, green macroalgal species, including R. fontinale and Prasiola crispa have also been known to synthesize AuNPs. Due to their application in targeted medication delivery for cancer treatment, AuNPs have gained prominence lately. The synthesis of AuNPs is always difficult because of their irreproducibility at the perfect dimension and form; however, green macroscopic algae overcame this difficulty and produced constant and repeatable AuNPs (Lakshmi et al., 2012; Parial and Pal, 2014; Priyadharshini et al., 2014).

Tetraselmis indica extract creates ZnO nanoparticles during the reduction of zinc acetate using a green synthesis technique. The DPPH free radical scavenging assay was used to inquire the zinc oxide nanoparticles’ antioxidant capacity. Acquiring hydrogen or electrons from the donor atom, which are then taken up by the odd electron of DPPH and change into identical hydrazine, reduces the free radical of 1-diphenyl-2-picrylane (Bhakya et al., 2016). The absorbance at 517 nm is used to quantify the observed decline of the colour faded from purple to yellow. When compared to ascorbic acid, the zinc nanoparticles’ free radical scavenging activity was nearly alike. The concentration of 100 mg mL−1 showed the greatest percentage of inhibition, indicating an 87.31% reduction, and this was higher than the concentrations of 75 mg mL−1%–77.62% and 50 mg mL−1%–65.35%. The green ZnO NP that was produced from Tetraselmis indica was an effective scavenger of hydroxyl radicals. One significant antioxidant component in ZnO was phenol (Thirumoorthy et al., 2021). The synthesized UL-ZrO₂NPs using the Ulva lactuca extract were assessed for antioxidant activity, and the results were profoundly efficient. The activity was measured using the DPPH method with standard ascorbic acid. In comparison to traditional ascorbic acid, UL-ZrO₂NPs demonstrated a little lower antioxidant activity as illustrated in Figure 4.

Utilizing the DPPH (2,2-diphenyl-2-picrylhydrazyl hydrate) test, the antioxidant plausible of both AgNPs and AuNPs was synthesized from cell-free extract of Neodesmuspupukensis. To dissolve 1.97 g of DPPH, 5 mL of methanol was used. Three millilitres of hydrogel solution, 1 mL of prepared hydrogel in 10 mL of distilled water, were combined with 1 mL of this solution. The concoction was agitated and kept at rest at ambient temperature for half an hour. Utilizing a UV-visible spectrophotometer, the absorbance at 517 nm was calculated. When it came to scavenging free radicals against 2,2-diphenyl1-picrylhydrazyl, NP-AuNPs exhibited the highest capacity (68.96%), followed by NP-AgNPs (41.21%), with the cell-free extract of Neodesmus pupukensis demonstrating the lowest ability (37.56%). Due to its simplicity and speed of usage, DPPH has become a useful technique for determining a compound’s antioxidant potential. The nanoparticles exhibited a higher level of antioxidant activity in comparison to the N. pupukensis cell-free extract. This suggests that the N. pupukensis nanoparticles have better antioxidant qualities than the extract derived from cells, highlighting their potential for use in medicinal and biotechnological fields (Omomowo et al., 2020).

The antioxidant properties of the green alga extract Botryococcus braunii were assessed in order to synthesize palladium and platinum nanoparticles. Using the serial dilution approach, green algae were gathered, separated, and cultured on Chu-13 nutritional medium. Palladium and platinum nanoparticles produced by algae were categorized using scanning electron spectroscopy and X-ray diffraction. Using 1,1-diphenyl-2-picrylhydrazyl, the antioxidant activity of the nanoparticles was investigated. By measuring the DPPH free radical scavenging activity, the antioxidant ability of the green produced palladium and platinum nanoparticles was assessed. The DPPH solution eventually turned pale yellow in the presence of nanoparticles, changing from purple over time. The percentage of DPPH that was foraged grew undeviated as the nano-mediated particle density increased from 1 to 20 μg/mL. For palladium, this occurred within 30 min at 20 μg/mL, while for platinum, it reached 78.14% at 25 μg/mL (Arya et al., 2020).

Zinc acetate dihydrate and zinc nitrate hexahydrate were used as forerunners for the biofabrication and capping of ZnO NPs, which were made possible by the bioactive compounds found in Shyalina extract. The radical neutralizing activity of the produced ZnONPs was measured by DPPH. ZnO nanoparticles derived from algae exhibited exceptional scavenging ability (IC₅₀ = 16.1 ± 0.74 μg/mL and 18.89 ± 0.63 μg/mL) in contrast to algal extract (IC₅₀ values of 21.2 ± 0.98 μg/mL). A chemical with a low IC₅₀ value has a higher scavenging activity. ZnO NPs derived from algae had lower IC₅₀values, indicating a higher potential for antioxidant activity. This could be because, following the creation of ZnO NPs, phenolic compounds were more active. Because of their strong antioxidant activity and capacity to function as reducing agents, phenolic active compounds, which are present in algal extract, are important in the production of ZnONPs (Hameed et al., 2023).

The excess biomass of the microalgae Acutodesmus dimorphus was utilized to create a micro-algal water extract following lipid extraction, which was subsequently utilized to create silver nanoparticles (2–20 nm) (Mukherjee et al., 2021). One litre of Erlenmeyer flasks holding 500 mL of dairy wastewater were used to culture A. dimorphus. After being infused (10% v/v) into the flasks, the actively growing culture of A. dimorphus was incubated at 35 °C with 60 μmol m⁻² s⁻¹. For 8 days, there was a light-dark cycle of 12:12 h with a light intensity (cool white fluorescent lamps). To prevent the cells from adhering to the flask surface, the flasks were manually shaken three times a day. As mentioned in the earlier study (Chokshi et al., 2016), the dried microalgal biomass was used to extract lipid using a chloroform: methanol (1:2, v/v) ratio. The biosynthesized silver nanoparticles’ antioxidant capacity was evaluated through the utilization of 2,20-azino-bisphosphate (3-ethylbenzothiazoline-6-sulfonic acid) (Chokshi et al., 2016). The utilization of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) in evaluating the antioxidant capacity of biosynthesized silver nanoparticles, which involves:

ABTS Radical Cation (ABTS•+) Formation: When ABTS is oxidized, it produces the radical cation form (ABTS•+), which is the form that is most frequently employed. The maximal absorbance of this blue-green radical cation is around 734 nm in wavelength.

Given below is Table 3 of nanobioparticles showing antioxidant properties relevant to SDGs:

Studies on the antibacterial activity of nanoparticles stemmed fromgreen algae against many strains of bacteria. Zinc acetate was reduced utilizing a green synthesis technique, employing Tetraselmis indica algae extract as a precursor to produce ZnONPs. By using the Agar well diffusion method, it was determined that the biosynthesized ZnONPs exhibited antimicrobial actionupside topathogenic bacteria. Among the chosen bacterial strains, the most susceptible and resilient were the Gram-positive S. aureus, with a maximum zone of 18.4 ± 0.5 mm, and the Gram-negative E. coli, with a minimum zone of 12.3 ± 0.3 mm. Since the zone of inhibition increases with increasing ZnONPs concentration, we can infer that the antibacterial property is directly correlated with the analyte concentration used. This makes sense given that a high concentration of ZnONPs will enter the bacterial cell wall, leading to more effective antibacterial activity (Thirumoorthy et al., 2021). Botryococcus braunii green algal extract was used to create palladium and platinum nanoparticles. Without the use of chemicals as reducing agents, algae extract seems to be a promising source of reducing and stabilizing agents. Visual inspection was used to check the entire metal nanoparticle production process at first. Two Gram-positive bacterial strains, K. pneumoniae (MTCC 109) and S. aureus (MTCC 96), and two Gram-negative bacterial strains, P. aeruginosa (MTCC 441) and E. coli (MTCC 442), were used to test the antibacterial activity of platinum and palladium nanoparticles. PtNPs and PdNPs at 400 μg/mL concentration demonstrated the highest zone of inhibition against the test pathogens. The nanoparticles generated from that algal culture exhibit antibacterial activity, with a zone of inhibition spanning from 7 to 16 mm (Arya et al., 2020).

The green-synthesized NiO nanoparticles’ antibacterial activity was tested against Gram-positive S. aureus and Gram-negative E. coli, K. pneumoniae, and P. aeruginosa pathogens utilizing the disk diffusion method. Figures 5a,b provides the zones of inhibition (ZOI) at various concentrations of NiO nanoparticles. Research focused on the effect of silver nanoparticles on the bacterial release of intracellular components. Various concentrations of the nanoparticles were administered to P. aeruginosa, B. cereus, S. aureus, and K. pneumoniae. Increments of A₂₆₀ correlating to the concentration of nanoparticles were found, with P. aeruginosa yielding the greatest values at 25 mg/mL and 1 h of exposure, as reflected in Figure 5d.

The cell-free extracts of microalgae N. pupukensis were used to create gold (AuNPs) and AgNPs. The Evaluation of antimicrobial properties from these nanoparticles was done against five different bacteria using agar well diffusion method. While NP-AuNPs were only moderately active against both Pseudomonas sp. and S. marcescens, with zone of inhibition of 27.5 mm and 28.5 mm, respectively, AgNPs demonstrated a high antibacterial potency of 43 mm, 24.5 mm, 27 mm, and 39 mm against P. aeruginosa, E. coli, K. pneumoniae, and S. marcescens, respectively. Staphylococcus aureus was inhibited by NP-AgNPs and NP-AuNPs with respective activities of 24.5 and 17.5 mm (Omomowo et al., 2020).

Utilizing zinc acetate dihydrate and zinc nitrate hexahydrate as predecessors, Spirogyra hyaline decoction was used for the biofabrication and capping of ZnONPs. The structural and optical modifications of the novel biosynthesized ZnONPs were investigated using energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis spectroscopy, and Fourier transform infrared spectroscopy (FT-IR). Among P. aeruginosa, B. pumilus, S.s aureus, and E. coli, ZnONPs [Precurssor: ZA (Zinc acetate) and ZN (Zinc nitrate)] showed different levels of activity, with distinct zones measuring 15.33 ± 0.42, 16.33 ± 1.14, 24.33 ± 1.12, and 16.67 ± 0.92 mm, in that order. The zones of inhibition against bacterial strains grew as the nanoparticle mass concentration increased. Algal-based ZnONPs showed excellent antibacterial activity in contrast to that of algal extract against the diverse strains of Gram-positive and Gram-negative bacteria. Zinc oxide NPs demonstrated substantial antibacterial activity against Gram-positive bacteria, especially S. aureus (Hameed et al., 2023).

The marine algae Caulerpa serrulata was used to create strong and colloidal-shaped silver nanoparticles, which had remarkable antibacterial efficacy against Shigella sp., S. aureus, E. coli, P. aeruginosa, and Salmonella typhi at lower doses (Mukherjee et al., 2021). Salmonella typhi exhibited the least zone of inhibition at 10 mm at 50 µL solution of silver nanoparticles, but E. Coli had the biggest zone of inhibition at 21 mm (Aboelfetoh et al., 2017).

AgNPs extracted from P. oedogonia aqueous extract have demonstrated promising antibacterial action against E. coli, M. luteus, S. aureus, B. subtilis, Vibrio cholerae, P. aeruginosa, and Shigella flexneri. AgNPs exhibit remarkable antibacterial efficacy against highly resistant Gram-negative rods, as demonstrated by the measurement of the maximum zone of inhibition (17.2 mm) for P. aeruginosa (Sinha et al., 2015).

Using the disc diffusion assay, the antibacterial efficacy of C. minutissima extract-derived Ag-NPs was evaluated against possible human pathogens, including E. coli, Salmonella sp., Klebsiella sp. (Gram-negative), Bacillus cereus, and Staphylococcus aureus (Gram-positive). The greatest zone of inhibition that Ag-NPs produced against B. cereus (21 ± 1 mm) was higher than that of S. aureus (20 mm) and E. coli (20 mm) among the five test bacterial species. Ag-NPs were found to be moderately effective against Salmonella spp. (17 ± 1 mm) and Klebsiella sp. was found to be minimally vulnerable toward Ag-NPs. At pH 9, a stable and high yield of Ag-NPs was obtained with a ratio of 1:10 for the precursor metal salt solution to algal extract and a concentration of 10 mM for AgNO₃ (Kumar et al., 2024a). Therefore, the green synthesis technique that uses algae extract instead of more traditional physical and chemical methods for the production of Ag-NPs turns out to be a cost-effective, efficient, environmentally friendly, economically viable, and long-lasting strategy. To combat antibiotic resistance, large-scale Ag-NP production is possible with C. minutissima. Utilizing these Ag-NPs can help reduce the microbial load and treat wastewater effluent and synthesize silver nanoparticles using algae (Kumar et al., 2024a). Given below is table 4 of nanobioparticles showing antioxidant properties relevant to SDGs:

The antifungal activity of AuNPs produced from algae has also been studied; however, the results of these investigations are scarce A. niger, C. albicans, and Candida parapsilosis fungal strains have all shown significant growth retardation when exposed to AgNPs biosynthesized from green algae, Ulva latica (Dhavale et al., 2020). Recently, some of the research groups evaluated the fungicidal activityof biosynthesized silver nanoparticles by dissolving 1 mg of silver nanoparticles in DMSO and inoculating them with fungal isolates. The nanoparticles showed maximum zones of inhibition against F. solani, Rhizoctonia solani, and Fusarium proliferatum, as shown in Figure 5c. The mycosis-inhibiting capacityof AgNPs and AuNPs mediated by N. pupukensis was investigated. The graded concentrations of each compound were added to potato dextrose agar plates (Khatami et al., 2015). These plates were then infused with a 6 mm agar plug containing 48-hour-old cultures of five different fungi. AgNPs’ antifungal efficacy was verified by measuring their mycelial inhibition against A. niger, A. fumigatus, A. flavus, Fusarium solani, and C. albicans, which yielded 80.6%, 57.1%, 79.4%, 65.4%, and 69.8%, respectively. In contrast, AuNPs demonstrated 79.4%, 44.3%, 75.4%, 54.9%, and 66.4% against A. niger, A. fumigatus, A. flavus, F. solani, and C. albicans, respectively. NP-AgNPs (N. pupukensis–AgNPs) exhibited the greatest mycelial inhibition against A. niger (80.6%), whereas NP-AuNPs (N. pupukensis-AuNPs) had the least inhibition against F. solani (44.3%). Neodesmus pupukensis silver and gold nanoparticles were both very effective against the toxic fungus under investigation, and some of the plates displayed mycelial inhibition (Omomowo et al., 2020).

Using green algae Botryococcus braunii, stable palladium and platinum nanoparticles were effectively created. The study examined the antifungal properties of platinum and palladium nanoparticles in relation to the fungus Fusarium oxysporum (MTCC 2087). The agar well plate method was used to assessantimycotic efficacy testing of the nanoparticles in terms of the zone of inhibition of microbial growth, and an agar dilution experiment was used to estimate the lowest inhibitory dose. From that algal culture, nanoparticles were generated, and the highest zone of inhibition against the test strains was shown by PdNPs and PtNPs at 400 μg/mL concentration, with a zone of inhibition spanning from 7 to 16 mm, which proves that nanoparticles possess antifungal activity (Arya et al., 2020).

The green synthesis of silver nanoparticles (AgNPs) using filamentous algae extract of Spirogyra sp has demonstrated anti-biofilm properties against nosocomial pathogens, specifically Staphylococcus aureus and Acinetobacter baumannii. The biosynthesized AgNPs exhibit a spherical morphology with sizes ranging from 20 to 30 nm and display significant biofilm formation of the tested bacterial strains. Characterization techniques such as UV-Vis spectroscopy, XRD, and FTIR analyses confirmed the successful creation of AgNPs and indicated their interactions with phytochemicals in the algae extract (Danaei et al., 2021).

The following study has shown the potential of lutein, a carotenoid extracted from the green microalga Chlorella pyrenoidosa, as an antibiofilm and quorum-sensing agent against Pseudomonas aeruginosa, a pathogenic bacterium known for its resistance to antibiotics and ability to form biofilms. The study has also demonstrated that nutrient starvation enhances lutein production, which significantly inhibits biofilm formation and disrupts quorum-sensing mechanisms in P. aeruginosa. Through high-performance liquid chromatography (HPLC) and molecular docking studies, the research reveals that lutein interacts with key proteins involved in the quorum sensing system, leading to the downregulation of relevant genes. The findings suggest that lutein could be a valuable natural alternative for treating infections associated with biofilm-forming bacteria, particularly in cases where conventional antibiotics are ineffective (Sampathkumar et al., 2019). The interaction of nanoparticles with bacterial membranes and the consequent release of internal cellular components was evaluated by absorbance measurement at 260 nm as shown in Figure 5d. For 1 h and at 25, 35, and 45 μg/mL, silver nanoparticles were exposed with P. aeruginosa, Bacillus cereus, S. aureus, and Klebsiella pneumoniae. An increase of the A260 values was noted for all bacteria in relation to the concentration, and this indicates further membrane disruption and intracellular leakage.

The anti-biofilm potential of sulfated polysaccharides (SPs) derived from Chlamydomonas reinhardtii against the foodborne pathogens Salmonella enterica and Vibrio harveyi, isa significant contributor to foodborne diseases and antibiotic resistance. Cr-SPs effectively inhibit both planktonic growth and biofilm formation of these bacteria in a dose-dependent manner, with notable reductions in metabolic activity and extracellular polysaccharide production. The ability of Cr-SPs to not only prevent biofilm formation but also to eradicate preformed biofilms suggests their potential as a natural alternative therapeutic agent in combating bacterial infections associated with foodborne illnesses (Vishwakarma and Vavilala, 2019).

The green synthesis of zinc oxide nanoparticles (ZnONPs) utilizing methanol extract from Spirulina platensis, emphasizes their characterization and potential biomedical applications. The various analytical techniques, including FE-SEM, TEM, FTIR, and XRD, were used to assess the nanoparticles’ morphology, size distribution, and crystalline structure. The antibacterial efficacy of the synthesized ZnONPs is evaluated against standard bacterial strains such as S. aureus, Streptococcus pyogenes, Salmonella typhi, and K. pneumoniae, using methods like the Agar well diffusion assay and microtiter plate assays for biofilm quantification. Results demonstrated significant antibacterial and antibiofilm activity, particularly at sub-MIC concentrations, alongside a dose-dependent cytotoxic effect on Vero cells assessed through the MTT assay (Ahmed and Othman, 2024).

The potential of lipid extracts from S platensis as anti-biofilm agents against Candida sp. is a significant contributor to chronic wound infections. By optimizing extraction conditions using bio-sourced solvents, it was successfully isolated free fatty acids (FFA) were successfully isolated, demonstrating substantial antimicrobial activity, achieving up to 80% inhibition of biofilm growth at low concentrations. The encapsulation of these lipid extracts in copper-alginate nanocarriers not only enhanced their anti-biofilm efficacy but also ensured safety for keratinocyte cells, indicating compatibility for topical applications (Boutin et al., 2019).

Biologically synthesized nanomaterials designed for biomedical and environmental applications require assessment of hemocompatibility as part of the safety evaluation process. Algae-mediated green synthesis of nanoparticles is eliciting considerable interest for the eco-friendly and biocompatible phytochemicals which may affect blood compatibility. ZnO as an example of algae-derived metal oxide nanoparticles, is often assumed to be safe, but can under certain conditions interact with red blood cells (RBCs). Therefore, hemolytic assessment is critical for algae-derived nanoparticles. The larger probability of haemolytic activity was detected in 100 mg mL−1, indicating that when the ZnO nanoparticles come into surface contact with the RBC cells, haemoglobin is released into the blood plasma (Raja et al., 2014). Haemolysis, morphological traits, and osmotic fragility were considered when examining ZnONPs’ impact on RBCs. RBC fragility is caused by osmotic and mechanical stress on the membrane. Haemolysis of cleaned red blood cells was found to be safe within the 50 mg mL−1 range. This demonstrates that there will be negative health impacts from increased ZnO NPs concentrations. As a result, it makes sense that the produced ZnONPs’ haemolytic activity would depend on concentration (Thirumoorthy et al., 2021). It was found that very less studies were found on green algae nanoparticles, which can mediate hemolytic activity, whereas different studies on other algal classes like blue-green algae, red algae and brown algae were abundant.

The in vitro anticancer potential of gold nanoparticles (AuNPs) synthesized using Chaetomorpha linum was demonstrated against the human colon cancer cell line HCT-116. Treatment of cancer cells with these AuNPs resulted in dose-dependent cytotoxic effects. Further analysis revealed the induction of apoptosis, marked by the activation of caspase-3 and caspase-9 and a significant reduction in anti-apoptotic proteins such as Bcl-xl and Bcl-2. These findings clearly validate the effectiveness of algal-mediated AuNPs as potential anticancer agents (Acharya et al., 2021). Similarly, the cytotoxic potential of green-synthesized silver nanoparticles (AgNPs) derived from the marine green alga Chaetomorpha ligustica has been reported. The biosynthesis of AgNPs was confirmed through visual color change and characterized using UV–Vis spectroscopy and transmission electron microscopy. Notably, the synthesized AgNPs exhibited significantly higher cytotoxic activity against human colon cancer cell lines HT-29 and HCT-116 compared to the algal extract alone. These results highlight the superior anticancer efficacy of biogenic nanoparticles and their promise for future cancer research and therapeutic applications (Al-Zahrani et al., 2021). In another study, gold nanoparticles synthesized via green methods using the aqueous extract of the halotolerant microalga Dunaliella salina were characterized by UV–Vis spectroscopy, transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FTIR), confirming the formation of stable, spherical nanoparticles. The in vitro anticancer evaluation demonstrated selective cytotoxicity of these AuNPs against the breast cancer cell line MCF-7, while exhibiting minimal toxicity toward normal breast epithelial cells (MCF-10A). This selective action suggests their potential as safer alternatives to conventional chemotherapeutic agents such as cisplatin (Singh et al., 2019). More recently, Sudhakar et al. (2025) investigated the anticancer efficacy of zirconium oxide nanoparticles synthesized using U. lactuca against the A549 lung cancer cell line. Cells treated with U. lactuca-derived ZrO₂ nanoparticles (UL-ZrO₂NPs) showed pronounced morphological changes, including cell shrinkage and loss of structural integrity. These alterations provided clear evidence of the anticancer activity of UL-ZrO₂NPs.

Figure 6 examines the anticancer activity of zirconium oxide nanoparticles (ZrO₂NPs) made with the extract of Ulva lactuca. The images depict a concentration-dependent cytotoxic effect of zirconium oxide nanoparticles due to changes in cellular morphology, a decrease in the density of cells, and an increase in the number of dead cells at higher concentrations.

Green algae-based nanoparticles are an emerging and promising area of research in drug delivery systems. These nanoparticles, synthesized using extracts from green algae, have demonstrated remarkable potential in targeting specific cells for precise drug delivery. By functionalizing the surface of these nanoparticles, they can be engineered to selectively bind to target cells, such as cancer cells, thereby enhancing the therapeutic efficacy of drugs while reducing off-target effects and minimizing side effects. Their intrinsic biocompatibility and biodegradability make them safer alternatives to conventional synthetic nanocarriers, as they are less likely to trigger immune responses or toxicity in the body. Moreover, green algae-mediated nanoparticles can improve drug solubility, stability, and bioavailability, which is especially advantageous for oral and systemic drug delivery. Polysaccharides ulvan extracted from green algae Ulva, serve as natural biopolymeric precursors due to their unique physicochemical properties, non-toxicity and abundance. These polysaccharides can be formulated into polysaccharide nanomaterials (PNMs) that encapsulate drugs efficiently, allowing sustained and controlled release, protection from premature degradation, and targeted delivery to specific tissues or cells (Drori et al., 2024). Additionally, the sulfated polysaccharides from Ulva, composed primarily of rhamnose, uronic acids, and xylose, exhibit intrinsic bioactivity, such as antioxidant, anti-inflammatory, and anticancer properties, which can synergistically enhance the therapeutic outcomes of the loaded drugs. This dual function as both a delivery vehicle and a bioactive agent makes green algae-mediated nanoparticles a versatile and highly promising platform for next-generation drug delivery systems, particularly in oncology, antimicrobial therapy and other targeted biomedical applications.

Green algae mediated nanoparticles (NPs) have emerged as versatile agents for environmental remediation and biomedical applications due to their unique catalytic, biocompatible and sustainable properties. Under visible light, silver nanoparticles (AgNPs) generated by Ulva lactuca photocatalyzed the degradation of methyl orange dye. In addition, a low dosage of U. lactuca mediated AgNPs significantly reduced the population of Plasmodium falciparum, a species normally resistant to chloroquine (Kumar et al., 2013). Similarly, hazardous pollutants such as methyl orange and methylene blue were efficiently degraded by Chlorella ellipsoidea-mediated biomatrix-loaded AgNPs, and the catalytic efficiency remained stable even after three reduction cycles (Borah et al., 2020). In another study, lipid-cadmium sulfide nanoparticles were synthesized using the green algae Scenedesmus obliquus. During the synthesis process, a chemisorbed monolayer of Cd²⁺ ions irreversibly bonded to the algal biomass, reflecting a significant increase in the adsorption kinetics of Cd²⁺ ions. This excellent retention capability makes Scenedesmus an effective model alga for the bioremediation of heavy metals. Various algae mediated nanoparticles have also been employed to remediate a wide range of organic and aromatic chemicals, heavy metals, and dyes. Unlike traditional chemical remediation methods, nano-bioremediation operates at the molecular level, enabling precise targeting of pollutants while preserving surrounding flora and fauna. Moreover, the biocompatibility and biodegradability of algae-based nanoparticles minimize the risk of secondary pollution, making this approach a sustainable solution for environmental cleanup. By leveraging the natural properties of green algae along with nanotechnology, nano-bioremediation provides a low-impact, high-efficiency strategy for restoring polluted environments (Suarez et al., 2025).

Sudhakar et al. (2025) have investigated the capability of zirconium oxide nanoparticles from U. lactuca for the degradation of pollutants like Malachite Green (MG) and Eosine (E). Under sunlight irradiation, the photocatalytic degradation of MG was 93.6% of MG and 86.2% of E, as shown in Figures 7.a,b, respectively, after 180 min. After treatment with UV-ZrO₂NPs, the peak of MG and E stayed the same. Therefore, the green chemistry applied to generate UL-ZrO₂NPs from U. lactuca clearly proved the photocatalytic activity at 180 min. Table 5 summarize the microbial and pollutants removal by using algal species.

Nanoparticles derived from green algae have attracted substantial attention in food technology and preservation because of their peculiar traits, such as biocompatibility, antimicrobial activity, and antioxidant potential. Green algae-based nanoparticles can be incorporated into food packaging materials to constrain the development of pathogenic microorganisms, extending the shelf life of perishable foods. For example, silver nanoparticles synthesized from green algae have shown strong antimicrobial activity against foodborne pathogens like E. coli and Salmonella (Kathiraven et al., 2015). Green algae-based nanoparticles can be used in biosensors for the detection of food contaminants, such as heavy metals and pesticides, ensuring food safety (Kumar and Chen, 2008). Green algae-derived nanoparticles can offer a sustainable and eco-friendly approach to enhancing food preservation, packaging, and safety. Their antimicrobial, antioxidant, and nutrient delivery properties make them promising candidates for various applications in food technology. The successful synthesis of ZnONPs, with a mean size of 77.81 nm, characterized by flower and sphere shapes, was obtained using Ulva fasciata extract as a reducing and stabilizing agent. The nanoparticles exhibited strong antibacterial activity against foodborne pathogens such as Escherichia coli and Staphylococcus aureus, with the bactericidal effect being time-dependent and more potent than annealed ZnONPs. When applied to peeled shrimp during refrigerated storage, the ZnONPs significantly reduced microbial loads and maintained acceptable sensory attributes (appearance, odor, color, and texture) over 6 days. Ulva fasciata-derived ZnONPs can be a potential eco-friendly and effective bio-preservative for seafood, offering a sustainable alternative to conventional preservation methods (Alsaggaf et al., 2021).

Sustainability can be achieved using green algae through their versatile applications in synthesizing eco-friendly nanoparticles (NPs) with significant roles in potable water (SDG 6), economic energy (SDG 7), hunger elimination (SDG 2), and climate strategies (SDG 13). Green algae-mediated NPs, such as silver (AgNPs) and zinc oxide (ZnO NPs), are utilized for water purification, removing pollutants and pathogens, and enhancing biofuel production efficiency, offering sustainable alternatives to fossil fuels (Mukherjee et al., 2021). In agriculture, these NPs improve crop yields and soil health, reducing the need for chemical fertilizers, thus addressing food security challenges (Bhakya et al., 2016; Hameed et al., 2023). Additionally, green algae contribute to carbon sequestration and pollution reduction, aiding in climate change mitigation (Mata et al., 2010; Olabi et al., 2023). Despite challenges like scalability and economic viability, green algae-based NPs represent a promising, sustainable solution for global environmental and health challenges.