Both nature and science have long used nanoparticles. They serve as a bridge between bulk materials and molecular structures, which has made them of tremendous interest. They exhibit quantum effects while being so tiny. They have improved stability, strength, and reactivity in addition to having surprising optical features, all of which make them very important. They have been employed for a long time in a variety of industries, including cosmetics, the manufacture of iridescent glassware, the manufacture of weaponry, paints, pharmaceuticals, Roman pottery, textiles, and many others. Nanoremediation is the practice of using nanotechnology in remediation procedures. When compared to bulk materials, nanoparticles are atomic or molecular aggregates with sizes between 1 and 100 nm that might alter their physiochemical properties. Its classification, such as 0-dimensional and 1-dimensional nanoparticles, depends on how many dimensions electrons may be housed in [83]. They have special qualities that differentiate them from their bulk equivalents and give them a wider range of uses. Due to their small size, materials with a high surface area-to-volume ratio have unique physical and chemical properties. Both organic and inorganic nanoparticles (micelles, fullerenes, and dendrimers) are present (ceramic, steel, and metal oxide nanoparticles). Although nanoparticles can be polycrystalline or amorphous and have a variety of morphologies, including platelets, spheres, and cubes, nanocrystals are single-crystalline nanoparticles. Both chemical and biological processes have been used to create nanoparticles. The biological synthesis method is popular due to its low cost, quick synthesis, control over size and features, and toxicity. Self-organization and the production of molecules with highly selective properties are capabilities of biological systems. The physical properties of nanoparticles are influenced by size, shape, distribution, surface area, solubility, and structure. The surface area to volume ratio of nanoparticles increases exponentially as the number of molecules at the surface increases, making the surface more reactive [84].

Furthermore, as the nanoparticles size and shape change, so do their optical properties. The zeta potential, surface chemistry, photocatalytic capabilities, and chemical composition of nanoparticles define their chemical properties [85]. Green nanotechnology creates nanoparticles from living organisms such as bacteria and plants. Microbes have sparked interest in the production of nanoparticles due to their high tolerance, rapid purification, and reproducibility. It has been demonstrated that biologically produced nanoparticles have excellent catalytic reactivity and a specific surface area [86]. A capping agent delivered by microorganisms aids in preventing nanoparticle agglomeration. Extracellular nanoparticle production requires no downstream processing and is inexpensive [87].

An innovative technology that can be applied to the subject of environmental bioremediation is the combination of enzymes with nanomaterials. Nanomaterials, which are regarded as particularly fascinating matrices because of their distinctive physicochemical features, can be successfully used to immobilize a variety of physiologically active compounds. As a result of their potential to form nanobiocatalysts, nanoparticles are carriers that have undergone much research. Nanographene, nanotubes, nanofibers, and nanogels are only a few examples of innovative hybrid nanocomposites that are currently being developed. Many problems were exposed by heavy metal contamination of arable soil, including the phytotoxic effects of several elements, including Cd, Pb, Zn, and Cu. These are all well-known essential metals, but after the critical endogenous levels are surpassed, they lead to a number of phytotoxicities [88]. As a result, HMs are poisonous and regarded as environmental pollutants, bioremediation might be a good choice to treat contaminated areas. Although bioremediation is a great way to remove different kinds of pollution, it has significant drawbacks. For instance, bioremediation could not be effective in locations with high concentrations of harmful contaminants. It involves HMs and their salts [89]. Furthermore, as living standards have increased due to scientific and technological advancements, hazardous waste has increased. As a result, cleaning up the ecosystem by eliminating toxins with present technology is inefficient and useless. Living things have evolved to flourish in metal-rich surroundings by utilizing a variety of coping mechanisms. These procedures may entail modifying the harmful metal’s properties, rendering it less toxic, and producing pertinent metal nanoparticles. As a result, the production of nanoparticles is seen as a “by-product” of a resistance mechanism against a particular metal and can be used as a substitute method for doing so.

Understanding the behavior of nanoparticles requires knowledge of their morphology, particle size distribution, specific surface area, surface charge, and crystallographic characterization. For a variety of reasons, different nanomaterials (NMs) are used in bioremediation. For instance, when the matter is scaled down to the nanoscale, a material’s surface area per unit mass rises; as a result, more of the substance can come into contact with other components, which might alter the reactivity. Less activation energy is needed to facilitate chemical reactions because NMs have a quantum impact. A novel method called nanobioremediation is showing promise in several industries. Microorganisms are increasingly being used in the production of nanoparticles as nanofactories and as possible tools for environmental cleanup [90]. Nanoparticles and nanomaterials created by bacteria utilizing nanotechnologies are used in nanobioremediation to remove environmental pollutants from polluted locations, including HMs and organic and inorganic pollutants. Microbes, flora, and enzymatic remediation are the three main bioremediation techniques [91]. Jiamjitrpanich et al. [92] found that using Panicum maximum in nano-phytoremediation was a more efficient way to contaminate and remove contaminated soil. Magnetic nanoparticles have numerous uses in adsorption and catalytic pollution remediation, according to Ajmal et al. [93].

Immobilizing pollutants on-site has emerged as a practical and affordable technique for cleaning up contaminated soils. To identify a suitable material that takes into account low cost, high efficiency, greater stability, the least detrimental environmental effect, and maximal performance, several NM-based full-form modifications have been examined. Moreover, HMs from water and organic and inorganic contaminants from soil can be eliminated by nanoparticles. For instance, organochlorines and long-chain hydrocarbons are very resistant to microbial and plant breakdown [94]. The bioremediation method using several nanoparticle methods is shown in Table 2.

Numerous shortcomings of traditional remediation techniques have been overcome thanks to the application of nanotechnology. Utilizing biogenic nanoparticles or materials made from biological sources, nanobioremediation is an extension of nanotechnology that deals with the removal of pollutants from the contaminated area. Due to the size of the material, this process has an advantage over other ways since a smaller size would result in a larger surface area to volume ratio, which would open up more surface area for the reaction to take place. The environmentally and economically beneficial characteristics of green nanoparticles as additives for bioremediation have attracted a lot of interest recently. Nanoparticles and phytoremediation can be combined in enzyme-based bioremediation. Integrating nanotechnology and biotechnology would allow for the quick degradation of these substances by bacteria and plants. Nano-encapsulated enzymes would break down complex organic compounds into simpler ones. Bacteria may mobilize and immobilize metals, and in some situations, microorganisms that can decrease metal ions can precipitate metals at the nanometer scale [113]. Bacteria are also being studied as a possible “bio-factory” for producing nanoparticles such as gold, silver, platinum, palladium, titanium, titanium dioxide, magnetite, cadmium sulfide, and others [114]. According to Alao et al. [115], zerovalent nanoparticles can easily remove various metallic contaminants from soil and waste-water effluent. Several halogenated hydrocarbons, organic compounds, and radionuclides have also been remedied using nanoparticles. For Pb(II) and Cr, the degradation degree of nanoscale zerovalent iron is 30 times greater than that of iron powder (VI). In degrading arsenic forms (As (V) and As (III)), the degradation rate of nano-adsorbent iron oxide is 8–10 times faster than that of the micron scale. Filtering is a successful method for purifying nanoparticles further. Bacterial cells and surface layers have distinct metal-binding properties, making them useful in bioremediation and nanotechnology applications [115]. Bioremediation by microorganisms typically requires using known aerobic and anaerobic bacteria to remove pesticides and hydrocarbons. Rhizoremediation is a low-cost and successful method of cleaning polluted soils using the joint action of plants and their symbiotic bacteria in the rhizosphere.

Studies have been conducted on the use of NPs in the bioremediation of heavy metal-contaminated sites. It has been reported that they can relieve drought stress and reduce Cd toxicity in wheat plants by enhancing biomass, chlorophyll content, and antioxidant biocatalysis. Si NPs have been reported to reduce HM-induced phytotoxicity in wheat, rice, and peas. To lessen the detrimental effects of HMs on plant growth and development, new nanoremediation techniques must be developed [116]. Bacterial nanoparticles can bind to and concentrate dissolved metals and metalloid ions. They can convert toxic metal ions into non-toxic nanoparticles. Bacterial mobilization, immobilization, and metal precipitation all contribute to nanoparticle formation.

The versatility and diversity of bacteria-produced nanoparticles make it a viable strategy [117]. Bacteria detoxify their immediate cell environment by converting toxic metal species into metal nanoparticles. Bacterial biomolecules are used as stabilizing and capping agents in the production of nanoparticles. Extracellular synthesis of biogenic nanoparticles is more efficient and produces easier-to-remove nanoparticles. Extracellular synthesis of large quantities of nanoparticles is possible. Bacteria have been used to produce nanoparticles such as palladium, titanium, magnetite, gold, and silver. Bacteria have the potential to be used as a biocatalyst for inorganic material synthesis, a bioscaffold for mineralization, and an active participant in nanoparticle production. Biosynthesis using bacteria is a versatile, reasonable, and acceptable large-scale production technology [118]. It has been reported that biogenic manganese oxide nanoparticles produced by Pseudomonas putida, silver nanoparticles produced by Bacillus cereus, gold nanoparticles produced by Rhodopseudomonas, and biogenic selenium nanoparticles produced by Citrobacter freundii Y9 performed the best bioremediation [119,120,121,122].

As a result, nanotechnology greatly improves the process of bioremediation, and its application in heavy metal bioremediation has been widely exploited. Controlling, sensing, and remediating pollutants with nanoparticles are some approaches used to monitor and treat contaminants. Chatterjee et al. (2019) created myco-synthesized iron oxide nanoparticles to remove HMs from waste water. The extracellular synthesis of nanoparticles with Aspergillus niger BSC-1, a mangrove fungus, resulted in the successful synthesis of biogenic (fungus) nanoparticles in the form of nanoflakes (20–40 nm) that could remove chromium through adsorption with excellent efficiency at a specific pH and temperature [123]. Keskin et al. [98] developed effective Lysinibacillus sp.-encapsulated nanofibers with cyclodextrin for hexavalent chromium, nickel, and dye remediation. These nanofibers functioned as a carrier matrix and a food source for the encased bacterium. In the presence of a reducing biomolecule, magnetic iron nanoparticles were produced in a living D. radiodurans R1 strain and demonstrated remarkable arsenic removal capacity [124]. Subramaniyam et al. [125] successfully produced iron nanoparticles from Chlorococcum sp. MM11 can remediate and reduce 92% of hexavalent chromium to trivalent chromium. Mukherjee et al. [126] developed aloe vera-based biogenic nanoparticles. This environmentally friendly method has been demonstrated to be highly effective in removing arsenic from contaminated water [126]. Another study by Al-Qahtani demonstrated that zero-valent silver nanoparticles derived from Ficus benjamina leaf extract efficiently removed cadmium [127]. It was found that the initial metal ion concentration influenced contaminant clearance and that a color shift identified the creation of silver nanoparticles as brown [128,129]. Different types of PAHs and HMs can be dealt with by certain types of bacteria and fungi that are present in the environment concurrently or successively [130]. Although native to HMs-contaminated sites, filamentous fungi have significant bioremediation potential that is frequently untapped [131]. One of the largest gene pools of invertebrates, bacteria, fungi, algae, and protozoa can be found in soil [132]. A more effective and broad-spectrum breakdown of pollutants is made possible by engineering competent microbes to enhance cell membrane transport or enzymatic characteristics. Future bioremediation will be more effective and last longer because of modifications and adaptations made to nanotechnology.