Authors Archana Bachhetia Rakesh Kumar Bachhetibc Limenew Abatebc Azamal Husen
phytochemicals and or plant based-secondary metabolites are used for NPs fabrication because they act as reducing, stabilizing and or capping agents. Numerous Aloe spp. provides a huge opportunity for NPs fabrications. These particles are used for different biological applications such as cytotoxicity, UV protection, antibacterial activity, catalytic activity, antibio?lm potential, photocatalytic activity, antifungal and antioxidant activities. Aloe-based NPs fabrication is also affected by various factors such as type of metal, different Aloe spp., method of NPs formation, temperature, pH and type of solvent used. For instance, gold nanoparticles(Au-NPs) synthesized from Aloe vera record the smaller size (15 nm)in comparison to copper nanoparticles (Cu-NPs) (50 nm) and selenium nanoparticles (Se-NPs) (50 nm). Silver nano-particles (Ag-NPs) prepared from Aloe vera was smaller in size 11-23 nm as compared to Cu-NPs 50 nm. Copper oxide nanoparticles (CuO-NPs) synthesized from Aloe barbadensis have larger size (15- 30 nm) compared to CuO-NPs synthesized from Aloe vera (5-20 nm). Hexagonal-shaped zinc oxide nanoparticles (ZnO-NPs) synthesized from Aloe vera with the size of particle»25 nm ; while spherical-shaped Zn-NPs fabricated from Aloe barbadensis with the particle size of (25-40nm). Aloe-based phytochemical and their role in NPs fabrication. Recently, the chemical compounds presented in Aloe have been utilized for NPs fabrication. The functional group present in them act as a reducing agent which convert metal ions into metal or metal-oxide. Aloe vera is recorded as a most bioactive plant). Anthraquinones, polysaccharides, naphthalenones, proteins, enzymes, and organic acid are the main phytochemicals present in Aloe vera leaves and another Aloe spp. A possible mechanism of the formation of Ag-NP from Aloe vera and the chemistry involved is presentenced of a OH group in most phytochemicals obtained from Aloe spp. and this OH served as a reducing agent, converting metal ions into metal/metal oxide NPs. Also, carbonyl functional groups present in phytochemical of Aloe spp. play a signi?cant role in NPs fabrication, Metal NPs, Silver NPsAg-NPs are metallic particles with a size range of 1-100 nm that are extensively employed in manufacturing, biomedicine, and engineering. Further, chemical stability, high conductivity, and optical behavior are the unique feature of Ag-NPs used Aloe vera leaf extract to achieve in situ synthesis of Ag-NPs by using cotton textiles. Various application of Aloe-based NPs, Antimicrobial activity, besides the numerous applications of NPs in different disciplines, various metal/metal oxide NPs have been used as antimicrobial agents. Ag-NPs were prepared by using leaf extract of Aloe vera to study the antibacterial activity. The result showed that Ag-NPs exhibited antibacterial activity against Staphylococcus aureus and Escherichia coli compared to Aloe vera extract, which did not show any antibacterial activity. Ag-NPs synthesized from Aloe vera leaf extract exhibited antibacterial activity against Klebsiella pneumonia, Bacillus subtilis, and Salmonella typhi with an inhibition zone greater than 80 mm. Insitu, on cotton fabrics, Ag-NPs were synthesized from Aloe vera leaf extract. The cotton fabric was tested for three activities, antibacterial activity, UV protection, and laundering durability. The results indicated that cotton fabric loaded with synthesized NPs shows antimicrobial activity against Staphylococcus aureus and Escherichia coli. Also, cotton ?ber exhibited better UV protection activity, nonetheless both antibacterial and UV protection activity decreased with the increase in washing cycles. Recently, Au-NPs fabricated from Aloe vera leaf extract were tested for antimicrobial activity against Escherichia coli, and Staphylococcus aureus on NPs impregnated cotton fabric. Cotton fabric was cut in the dimension of 15 £30 mm and immersed in NPs solution. The results revealed that the growth of Staphylococcus aureus and Escherichia coli was inhibited in the fabric treated with Au-NPs. ZnO-NPs synthesized from peel extract of Aloe vera were tested for antimicrobial activity against bacteria Escherichia coli, Staphylococcus epidermidis, Klebsiella pneumonia, and against fungus Aspergillus oryzae and Aspergillus niger. The results showed that ZnO-NPs were effective against Escherichia coli and Aspergillus niger. Also prepared ZnO-NPs from Aloe vera extracts ichum coccodes while antibacterial activities againstEscherichia coli and Staphylococcus aureus. In another study, the leafextract of Aloe vera was utilized for the synthesis of Ag-NPs andtested for antifungal activity against two fungus species, Aspergillussp. and Rhizopus sp. Ag-NPs showed greater antimicrobial activityagainst Aspergillus sp. as compared to Rhizopus sp. (Medda et al.,2015). CuO-NPs prepared from Aloe vera extract were tested for anti-bacterial activity against three bacteria strains Flavobacterium Brachyphyllum, Pseudomonas ?uorescens, and Aeromonas hydrophila. The results indicate that synthesized CuO-NPs exhibit antibacterial activity against all bacterial pathogens even at a lower concentration (20 mg/mL). Antioxidant activity. living organisms produce reactive oxygen species (ROS) due to regular cellular metabolism and several external in?uences and or stress. ROS are highly reactive molecules and can damage cell structures like proteins, lipids, nucleic acids, carbohydrates and alter their functions. The shift in the balance between oxidants and antioxidants in favor of oxidants is termed oxidative stress. Antioxidants are compounds used to reduce the effect of oxidative damage or oxidative stress by preventing or reducing its oxidation process. The capacity of bioactive compounds to alleviate the stress of oxidative damage, increase with concentration, also reported that the NPs have good ability to act as antioxidants and helpful in preventing number of infectious diseases. Aloe vera leave extracts and AV-Ag-NPs for antioxidant activityby2,20-diphenyl- 1-picrylhydrazyl (DPPH), lipid peroxidation inhibition and reducing power assay. The antioxidant activity of Aloe vera extract and AV-Ag-NPs was improved with the increase in concentrations (100 mg/mL to 600 mg/mL). Antioxidant activity of Ag-NPs prepared from Aloe vera gel was tested by the DPPH method and reducing power assay. The results revealed that the Ag-NPs showed good dosage-dependent antioxidant activity compared to crude extract. Se-NPs prepared from Aloe vera extract were tested for antioxidant activity by ferric reducing antioxidant power (FRAP),2,20-azino-bis (3-ethylbenzothiazoline-6-sulphonicacid (ABTS), and DPPH assay. The result indicated that Se-NPs showed better activity than Aloe vera extract alone , the antioxidant activity of biosynthesis ZnO-NPs using plant extracts of Aloe vera by various methods such as hydroxyl radical scavenging, superoxide radical scavenging, hydrogen peroxide (H2O2), ABTS, and DPPH. The results con?rmed that ZnO-NPs possess a promising antioxidant activity, antioxidant effect oncerium oxide NPs (CeO-NPs), which were synthesized using Aloe vera leaf extract as a stabilizing agent. The cyclic conversion of cerium (III)oxide as Ce (III)O! Ce (IV)O !Ce (III) O by reaction with H2O2implied the uninterrupted antioxidant property of CeO-NPs. Metal salt Extract Aloe species Characterization UV-Vis FTIR XRD FESEM TEM SAED AFM EDX Zeta Potential Condition optimization-pH -Temperature -Concentration of Aloe extract -Concentration of metal salt-Time-Solvent used for extraction Nanoparticle Applications Antimicrobial, Antioxidant ,Anticancer, Catalytic ,Wound healing, Drug delivery, Applications of Aloe species-based nanoparticles. Catalytic activity NPs have been well known for their catalytic properties. High sur-face area of NPs increases their catalytic activity. They have advantages over conventional catalyst in term of selectivity, activity, reusability and ef?ciency synthesized Ag-NPs using Aloe vera and tested them for the catalytic activity to degrade organic dye. Results showed that synthesized Ag-NPs have excellent catalytic activities for the decomposition of organic dyes in the presence of NaBH4, synthesized BaMgAl10O17NPs (BMANPs) to check the catalytic activity. Under UV irradiation, the photocatalytic activity was increased for the degradation of wastewater polluted by BMANPs, with 95 percent disintegration of Acid Red 88 dye, catalytic activities of ZnO-NPs prepared using Aloe vera leave extract. The results con?rmed the biosynthesized ZnO nano sheets were particularly effective for the degradation of malachite green dye. The use of Aloe vera as wound healing behavior was also reported in the form of composite, membranes, and ?lm combined with a polymer such as chitosan and other man-made material, which could be very important in burning healing application and wound healing. Drug delivery systems, Drug delivery allows to achieve sustained and controlled drug release, produce site-speci?c delivery, maintain desired drug concentrations in blood and reduce side effects, ensuring effective treatment and promising relief. Some of the modern techniques involved in drug delivery systems are nano?bers, NPs, nanocomposites, micelles, and hydrogels; these contain drugs and a carrying vehicle mostly made of biodegradable polymers. They are mostly involved in vascular regeneration and cancer treatments, the applications of polycaprolactone(PCL) nano?bers composite for medicinal purposes and fabricated nano?bers from Azadirachta indica (neem), curcumin (Cur), and Aloe vera. Variety of nano?brous mats were fabricated and named as Cur/PCL/neem, Cur/PCL/AV, PCL/neem, PCL/AV, PCL/Cur, and PCL alone. The results obtained from the uniaxial testing machine showed that the increase in the amount of neem and curcumin, the value of Youngs modulus and tensile strength decrease. However, the mechanical behavior of these ?brous mat increase when the amount of Aloe vera increase. MTT assay was used to check anticancer activity against human breast cancer (MCF7 cell line) and lung cancer (A459cell line) which showed that 1% Aloe vera and 5% curcumin loaded PCL nano-?bre exhibited 15% more anticancer activity in comparison with the commercial drug (1% cis-Platin-loaded PCL nano?ber), another biosynthesized 5-?uorouracil(FU) NPs using Aloe vera extract. NPs prepared by using Aloe vera exhibited good cytotoxicity activity against colorectal cell lines (Caco-2) and adenocarcinoma cell line (HT-29. Aloe vera shell ash supported NiO.5ZnO.5Fe2O4magnetic NPs used to remove Pb (II) ions from an aqueous at different pH and different exposure times. The results indicate that at pH 9, time 15 minute and0.2g adsorbent dose were optimum conditions. In another study, Aloe vera shell ash supported Ni0.5Zn0.5Fe2O4NPs was utilized for the removal of Ag (I) from aqueous solution at different pH, concentration of Ag and absorbent dose. Optimum condition obtained were pH 5, time 30 minutes with absorbent dose 0.20 g with removal ef?ciency of 98.3% synthesized Aloe vera capped ZnS:Mn2+quantum Synthesized NPs have strong yellow emission at 590 nm resulting from4T1!6A1 (in photoluminescence emission spectra), so theses NPs can have possible application in medical research related to imaging. The mosquitocidal activity of Aloe vera extract and synthesized Ag-NPs was tested against Anopheles stephensi larvae (I-IV instar) and pupae. The Aloe vera extract showed some extent mosquitocidal activity, however the response was more with the synthesized Ag-NPs. Synthesized Ag-NPs were ef?cient even at low concentration against Anophelesstephensi with LC50value 6.113 ppm (pupae), 5.711 ppm (IV instar),4.982 ppm (III instar), 4.119 ppm (II instar), and 3.825 ppm (I instar). Also, synthesized NPs were tested in the ?eld against Anophelesstephensi which showed a larval reduction of 97.7, 86.6, and 74.5%after 72, 48, 24 h, respectively. Also, lithium titanate nanomaterial synthesized using Aloe vera extract has been reported for its use as an alternative anode for lithiumion batteries. The signi?cance and application of Aloe would be accelerated by using nano sci-ence. It gave opportunity of synthesis of Aloe-based NPs in different form such as nanocomposites, nano?bers, hydrogels, and sponges which can be used for their antibacterial, antioxidant, catalytic, wound healing, and tissue regeneration activities. Further, it has been noticed that the Aloe species (natural form/extracts) have been extensively used and many commercial products are available in the market, however very less NPs-based commercial products are detected. Therefore, extensive investigations are required in this direction to make Aloe-based NPs more commercial and functional.
