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Nanotechnology is a rapidly growing scientific field and has attracted a great interest over the last few years because of its abundant applications. Green nanotechnology is a multidisciplinary field that has emerged as a rapidly developing research area, serving as an important technique that emphasize on making the procedure which are clean, non-hazardous, and especially environmentally friendly, in contrast with chemical and physical methods currently employed for nanosynthesis. The biogenic routes could be termed green as these do not involve the use of highly toxic chemicals or elevated energy inputs during the synthesis. Differences in the bio-reducing agents employed for nanosynthesis can lead to the production of nanoparticles (NPs) having distinct shapes, sizes, and bioactivity. The exquitiveness of the green fabricated NPs have capacitated their potential applications in various sectors such as biomedicine, pharmacology, food science, agriculture, and environmental engineering. The present review summarizes current knowledge on various biogenic synthesis methods, relying on plants, waste biomass, and biopolymers and their reducing and stabilizing agents to fabricate nanomaterials. The main emphasis has been given on the current status and future challenges related to the wide-scale fabrication of nanoparticles for environmental remediation, pathogenicity, and agricultural applications.

The rapid spread of highly aggressive arboviruses, parasites, and bacteria along with the development of resistance in the pathogens and parasites, as well as in their arthropod vectors, represents a huge challenge in modern parasitology and tropical medicine. Eco-friendly vector control programs are crucial to fight, besides malaria, the spread of dengue, West Nile, chikungunya, and Zika virus, as well as other arboviruses such as St. Louis encephalitis and Japanese encephalitis. However, research efforts on the control of mosquito vectors are experiencing a serious lack of eco-friendly and highly effective pesticides, as well as the limited success of most biocontrol tools currently applied. Most importantly, a cooperative interface between the two disciplines is still lacking. To face this challenge, we have reviewed a wide number of promising results in the field of green-fabricated pesticides tested against mosquito vectors, outlining several examples of synergy with classic biological control tools. The non-target effects of green-fabricated nanopesticides, including acute toxicity, genotoxicity, and impact on behavioral traits of mosquito predators, have been critically discussed. In the final section, we have identified several key challenges at the interface between \"green\" nanotechnology and classic biological control, which deserve further research attention.

Of the various methods explored for the synthesis of nanoparticles, biogenesis of silver nanoparticles (AgNPs) received great attention due to their versatile properties. In this report, Daucus carota extract was used for the synthesis of AgNPs and ceftriaxone was conjugated with AgNPs to enhance their antimicrobial efficacy. The conjugated and unconjugated AgNPs were characterized by adopting UV-Vis spectroscopy, FTIR, AFM, DLS, and TEM, which revealed the SPR peak at 420 nm and spherical shaped nanoparticles of 20 nm size, respectively. The antimicrobial efficacies of the unconjugated AgNPs and ceftriaxone-conjugated AgNPs were tested against ceftriaxone-resistant human pathogens, Bacillus cereus , Staphylococcus aureus , Klebsiella pneumoniae , and Pseudomonas aeruginosa . The ceftriaxone-conjugated AgNPs showed high inhibitory action (23 mm) than the unconjugated AgNPs (18 mm) at the concentration of 50 μg/mL. Both the unconjugated and ceftriaxone-conjugated AgNPs were found to be non-toxic on EAC cells at 50 μg/mL. The dose-dependent cytotoxic activities were observed on increasing the concentration of the AgNPs. The ceftriaxone-conjugated AgNPs showed high activity than the unconjugated AgNPs. The enhanced activity could be useful to treat ceftriaxone-resistant human pathogens.

In recent years, the use of nanoparticle-based antimicrobials has been increased due to many advantages over conventional agrochemicals. This study investigates the utilization of common medicinal plant dandelion, Taraxacum officinale , for the synthesis of silver nanoparticles (TOL-AgNPs). AgNPs were evaluated for antimicrobial activity against two important phytopathogens, Xanthomonas axonopodis and Pseudomonas syringae. The morphology, size, and structure of TOL-AgNPs were characterized using UV-visible spectroscopy and X-ray diffraction (XRD). Fourier transform infrared spectroscopy (FT-IR) showed the presence of phytochemicals involved during synthesis of NPs. High-resolution transmission electron microscopy (HR-TEM) analysis shed light on the size of monodispersed spherical AgNPs ranging between 5 and 30 nm, with an average particle size of about 15 nm. The TOL-AgNPs (at 20 μg/mL concentration) showed significant antibacterial activity with significant growth inhibition of phytopathogens X. axonopodis (22.0 ± 0.84 mm) and P. syringae (19.5 ± 0.66 mm). The synthesized AgNPs had higher antibacterial activity in comparison with commercial AgNPs. Synergistic assays with standard antibiotics revealed that nanoformulations with tetracycline showed better broad-spectrum efficiency to control phytopathogens. They also possessed significant antioxidant potential in terms of ABTS (IC 50  = 45.6 μg/mL), DPPH (IC 50  = 56.1 μg/mL), and NO (IC 50  = 55.2 μg/mL) free radical scavenging activity. The TOL-AgNPs showed high cytotoxic effect against human liver cancer cells (HepG2). Overall, dandelion-mediated AgNPs synthesis can represent a novel approach to develop effective antimicrobial and anticancer drugs with a cheap and eco-friendly nature.

The development of neuroprotective drugs through eco-friendly production routes is a major challenge for current pharmacology. The present study was carried out to synthesize gold nanoparticles (AuNPs) through biogenic route using ethanolic bark extract of Terminalia arjuna , a plant of high interest in Asian traditional medicine, and to evaluate its neuroprotective effects . The synthesized AuNPs were characterized by UV-Vis spectroscopy, FTIR spectroscopy, XRD, FESEM, EDX, HRTEM, DLS, and zeta potential analyses. UV-Vis spectroscopy showed a characteristics SPR absorption band at 536 nm specific for AuNPs. XRD, TEM, and FESEM analyses revealed the formation of face-centered cubic crystalline, spherical and triangular shaped AuNPs, with size ranging between 20 and 50 nm. DLS and ZP analysis illustrated that the average size of AuNPs was 30 nm, which was found to be stable at 45 mv. The neuroprotective potential of AuNPs was evaluated by assessing its antioxidant, cholinesterase inhibitory, and antiamyloidogenic activities. AuNPs showed dose-dependant inhibition of acetylcholinesterase and butyrylcholinesterase with IC 50 value of 4.25 ± 0.02 and 5.05 ± 0.02 μg/ml, respectively. In vitro antioxidant assays illustrated that AuNPs exhibited the highest reducing power and DPPH radical scavenging activity. In addition, AuNPs also efficiently suppressed the fibrillation of Aβ and destabilized the preformed mature fibrils. Results of toxicity studies in PBMC and adult zebra fish illustrated that AuNPs are non-toxic and biocompatible. Overall, our results highlighted the AuNPs promising potential in terms of antioxidant, anticholinesterase, antiamyloidogenic effects, and non-lethality allowing us to propose these nanomaterials as a suitable candidate for the development of drugs helpful in the treatment of neurodegenerative disorders like Alzheimer’s disease. Graphical abstract ᅟ

Titanium dioxide nanoparticles are emerging as a biocompatible nanomaterial with multipurpose bioactivities. In this study, titanium dioxide (TiO 2 ) nanoparticles were effectively synthesized using the aqueous leaf extracts of Parthenium hysterophorus prepared by microwave irradiation. TiO 2 nanoparticles were fabricated by treating the P. hysterophorus leaf extracts with the TiO 4 solution. Biologically active compounds such as alcohols, phenols, alkanes, and fluoroalkanes were involved in bioreduction of TiO 4 into TiO 2 . The formation of green-engineered TiO 2 nanoparticles was confirmed by UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), and energy-dispersive X-ray (EDX) spectroscopy and further characterized by X-ray diffraction (XRD) studies. UV-vis spectroscopy analysis showed maximum absorbance at 420 nm due to surface plasmon resonance of synthesized TiO 2 NPs. FTIR spectrum of the engineered TiO 2 NPs showed the presence of bioactive compounds in the leaf extract, which acted as capping and reducing agents. FESEM exhibited an average size of 20–50 nm and a spherical shape of TiO 2 NPs. EDX analysis indicated the presence of TiO 2 NPs by observing the peaks of titanium ions. XRD results pointed out the crystalline nature of engineered TiO 2 NPs. The larvicidal activity of TiO 2 NPs was studied on fourth instar larvae of dengue, Zika virus, and filariasis mosquito vectors Aedes aegypti and Culex quinquefasciatus. Antimicrobial efficacy of TiO 2 NPs was assessed on clinically isolated pathogens Escherichia coli , Staphylococcus aureus , Pseudomonas aeruginosa , Klebsiella pneumoniae , Proteus vulgaris , and Staphylococcus epidermidis . Besides, we found that TiO 2 NPs are able to quickly degrade the industrially harmful pigments methylene blue, methyl orange, crystal violet, and alizarin red dyes under sunlight illumination. Overall, this novel, simple, and eco-friendly approach can be of interest for the control of vector-borne diseases, as well as to formulate new bactericidal agents and to efficiently degrade dye solutions in the polluted areas.

In the attempt to exploit the potential of the monoecious fiber hemp cv. Futura 75 in new fields besides textile, cosmetics and food industry, its crop-residue given by leaves and inflorescences was subjected to hydrodistillation to obtain the essential oils. These are niche products representing an ideal candidate for the development of natural insecticides for the control and management of mosquito vectors, houseflies and moth pests. After GC-MS analysis highlighting a safe and legal chemical profile (THC in the range 0.004–0.012% dw), the leaf and inflorescence essential oils were investigated for the insecticidal potential against three insect targets: the larvae of Culex quinquefasciatus and Spodoptera littoralis and the adults of Musca domestica . The essential oil from inflorescences, showing ( E )-caryophyllene (21.4%), myrcene (11.3%), cannabidiol (CBD, 11.1%), α-pinene (7.8%), terpinolene (7.6%), and α-humulene (7.1%) as the main components, was more effective than leaf oil against these insects, with LD 50 values of 65.8 μg/larva on S. littoralis, 122.1 μg/adult on M. domestica , and LC 50 of 124.5 μl/l on C. quinquefasciatus larvae. The hemp essential oil moderately inhibited the acetylcholinesterase (AChE), which is a target enzyme in pesticide science. Overall, these results shed light on the future application of fiber hemp crop-residue for the development of effective, eco-friendly and sustainable insecticides.

Essential oils (EOs) from plants may be alternative sources of molecules toxic against mosquito vectors of public health relevance. Most of researches in this field focused on EOs as larvicides or ovicides, while limited efforts focused on the exploitation of EOs as oviposition deterrents. In the present study, the larvicidal and oviposition deterrent activity of Syzygium lanceolatum leaf EO was evaluated against six mosquito species, Anopheles stephensi , An. subpictus , Aedes aegypti , Ae. albopictus , Culex quinquefasciatus , and Cx. tritaeniorhynchus. The chemical composition of the S. lanceolatum EO was analyzed by GC-MS analysis, showing the presence of phenyl propanal, β-caryophyllene, α-humulene, and caryophyllene oxide as major constituents. S. lanceolatum EO showed high acute toxicity on An. stephensi (LC 50  = 51.20 μg/ml), Ae. aegypti (LC 50  = 55.11 μg/ml), Cx. quinquefasciatus (LC 50  = 60.01 μg/ml), An. subpictus (LC 50  = 61.34 μg/ml), Ae. albopictus (LC 50  = 66.71 μg/ml), and Cx. tritaeniorhynchus (LC 50  = 72.24 μg/ml) larvae. Furthermore, the EO was effective as oviposition deterrent against the six tested mosquito species, with OAI on An. stephensi , An. subpictus , Ae. aegypti , Ae. albopictus , Cx. quinquefasciatus , and Cx. tritaeniorhynchus reaching −0.83, −0.81, −0.84, −0.83, −0.84, and −0.86, respectively. The toxicity of S. lanceolatum EO against several biological control agents of mosquitoes, including water bugs ( Anisops bouvieri and Diplonychus indicus ) and fishes ( Gambusia affinis and Poecilia reticulata ), was extremely low, with LC 50 ranging between 4148 and 15,762 μg/ml. Overall, our results pointed out the promising potential of the S. lanceolatum leaf EO as a source of environmental-friendly oviposition deterrents and larvicides effective against a wide number of mosquito species of importance for parasitology.

Green and nanoacaricides including essential oil (EO) nanoemulsions are important compounds to provide new, active, safe acaricides and lead to improvement of avoiding the risk of synthetic acaricides. This study was carried out for the first time on eriophyid mites to develop nanoemulsion of garlic essential oil by ultrasonic emulsification and evaluate its acaricidal activity against the two eriophyid olive mites Aceria oleae Nalepa and Tegolophus hassani (Keifer). Acute toxicity of nanoemulsion was also studied on male rats. Garlic EO was analyzed by gas chromatography–mass spectrometry (GC-MS), and the major compounds were diallyl sulfide (8.6%), diallyl disulfide (28.36%), dimethyl tetrasulfide (15.26%), trisulfide,di-2-propenyl (10.41%), and tetrasulfide,di-2-propenyl (9.67%). Garlic oil nanoemulsion with droplet size 93.4 nm was formulated by ultrasonic emulsification for 35 min. Emulsification time and oil and surfactant ratio correlated to the emulsion droplet size and stability. The formulated nanoemulsion showed high acaricidal activity against injurious eriophyid mites with LC 50 298.225 and 309.634 μg/ml, respectively. No signs of nanoemulsion toxicity were noted in treating rats; thus, it may be considered non-toxic to mammals. Stability of garlic oil nanoemulsion, high acaricidal activity, and the absence of organic toxic solvents make the formulation that may be a possible acaricidal product. Results suggest the possibility of developing suitable natural nanoacaricide from garlic oil.

Anopheles stephensi acts as vector of Plasmodium parasites, which are responsible for malaria in tropical and subtropical areas worldwide. Currently, malaria management is a big challenge due to the presence of insecticide-resistant strains as well as to the development of Plasmodium species highly resistant to major antimalarial drugs. Therefore, the present study focused on biosurfactant produced by two bacteria Bacillus subtilis A1 and Pseudomonas stutzeri NA3, evaluating them for insecticidal applications against malaria mosquitoes. The produced biosurfactants were characterized using FT-IR spectroscopy and gas chromatography-mass spectrometry (GC-MS), which confirmed that biosurfactants had a lipopeptidic nature. Both biosurfactants were tested against larvae and pupae of A. stephensi . LC 50 values were 3.58 (larva I), 4.92 (II), 5.73 (III), 7.10 (IV), and 7.99 (pupae) and 2.61 (I), 3.68 (II), 4.48 (III), 5.55 (IV), and 6.99 (pupa) for biosurfactants produced by B. subtilis A1 and P. stutzeri NA3, respectively. Treatments with bacterial surfactants led to various physiological changes including longer pupal duration, shorter adult oviposition period, and reduced longevity and fecundity. To the best of our knowledge, there are really limited reports on the mosquitocidal and physiological effects due to biosurfactant produced by bacterial strains. Overall, the toxic activity of these biosurfactant on all young instars of A. stephensi , as well as their major impact on adult longevity and fecundity, allows their further consideration for the development of insecticides in the fight against malaria mosquitoes.