**4. Applications of biodegradable nanomaterials**

Biodegradable nanomaterials or nanoparticles include two major types: nanomaterials directly synthesized from various biopolymers such as polypeptides, polysaccharides and polynucleotides; and metallic nanoparticles, which are colloidal particles encapsulated inside a polymer matrix. The selection of this biopolymer matrix is based on many factors, including the size of the nanoparticles, degree of biocompatibility and biodegradability, surface properties and functionality and the type of application [63]. These biodegradable nanoparticles are typically in the 10–500 nm size range. Widely used methods for the fabrication of biodegradable nanoparticles include emulsification, solvent evaporation, coprecipitation, desolvation, coacervation, electrospray and electrospinning [63]. Over the past few years, many studies have been conducted in various fields on the preparation and applications of biodegradable nanomaterial. However, the applications in food packaging, energy, environmental remediation, and nanomedicine are discussed in this section.

*Novel Acumens into Biodegradation: Impact of Nanomaterials and Their Contribution DOI: http://dx.doi.org/10.5772/intechopen.98771*

#### **4.1 Food packaging**

Packaging plays an imperative role in the food industry. The major function of packaging is protecting food from physical damage while handling, transporting and storage. Packaging materials also maintain the food quality by protecting against air, moisture, insects, light, and dust and prevent contamination from chemical and biological sources. Commonly used packaging materials include plastics, metals, paper and paper boards, glass, and other traditional materials. However, food packaging accounts for 50% of petroleum-based plastics [64]. Upon disposal, plastics remain in the environment taking many years to degrade. The fragments of plastics, also known as microplastics, enters the ecosystems via food chains causing growing environmental and health concerns. Therefore, there is a significant interest in the development of environmentally friendly food packing alternatives. Biodegradable nanoparticles have recently been employed for food packaging applications due to their simple synthesis route, non-toxicity, relative abundance, low cost, and eco-friendly nature. Following are recent food packing applications of biodegradable nanoparticles reported.

Pandey *et al.* prepared the biodegradable meat packaging material using fibrous composite nano-layers (PVA-CH-AgNPs-FCNLs) as an alternative for plastic packaging [65]. PVA-CH-AgNPs-FCNLs were synthesized by electrospinning of a blend of silver nanoparticles (AgNPs) incorporated chitosan (CH) and polyvinyl alcohol (PVA). PVA-CH-AgNPs-FCNLs showed bioactivity against *Escherichia coli* (gramnegative bacteria) and *Listeria monocytogens* (gram-positive bacteria) and extended the meat shelf-life by one week [65]. Ediyilyam and coworkers investigated biodegradable films prepared from silver nanoparticles (AgNPs) incorporated chitosan (CH) and gelatin (GE) polymer blend for food packaging applications [66]. They reported the improved physicochemical and biological functioning of the films upon incorporating the AgNPs. CH–GE–AgNPs films also displayed antimicrobial activity against bacteria and fungi and enhanced the shelf life of carrot pieces wrapped in them over ten days [66].

Kumar *et al*. developed low-cost biodegradable nanocomposite hybrid films containing chitosan, gelatin, and zinc oxide nanoparticles (ZnO NPs) [67]. ZnO NPs reinforced hybrid nanocomposites exhibited enhanced thermal stability, elongation-at-break (EAB), and compactness properties with antimicrobial activity against *Escherichia coli* (gram-negative) bacteria. The authors claimed that these hybrid nanocomposite films have the potential to be developed as biodegradable postharvest packaging of fresh fruits and vegetables [67]. Saral Sarojini and coworkers fabricated the biodegradable food packaging films from Mahua oil-based polyurethane (PU) and chitosan (CS), incorporated with zinc oxide nanoparticles [68]. They reported enhanced hydrophobicity of the film by about 63%, high UV-screening ability, high transparency, high degree of biodegradation of 86%, and antimicrobial resistance for the ZnO incorporated PU/CS films. ZnO-reinforced PU/CS films also extended their shelf life up to nine days upon wrapped with carrot pieces [68].

Starch-based (St) nanocomposite films prepared by incorporating silver (Ag), copper oxide (CuO) and zinc oxide (ZnO) nanoparticles (NPs) were tested for physicomechanical and antimicrobial properties by Peighambardoust *et al*. [69]. Ag/ ZnO/CuO NPs incorporated starch-based films showed better antimicrobial and mechanical properties due to the synergistic effect. The authors reported the potential use of these starch-based nanocomposites as food packaging materials [69]. Colored biodegradable dye (methylene blue)-clay (montmorillonite)-nanopigment (DCNP) polylactic acid (PLA) nanocomposite films were prepared and tested for various functional properties by Mahmoodi *et al*. [70]. The PLA-DCNP films exhibited high

mechanical strength, barrier properties, blocking effect against destructive radiation, biodegradability properties, and potential food packaging applications [70].

#### **4.2 Energy**

Recent advancement in biodegradable nanomaterials has led to the development of energy-efficient devices including ignition engines, solar cells, supercapacitors, and rechargeable batteries. Current applications of biodegradable polymers in energy-efficient devices are discussed below.

Ettefaghi *et al*. investigated the biodegradable carbon-based quantum dots as alternatives for metal and metal oxide fuel additives [71]. The use of a combination of diesel-biodiesel-water-biodegradable carbon nanoparticles showed an increase in engine torque and power and a decrease in brake-specific fuel consumption. The bio-nano emulsion fuels also reduced the emission of nitrogen oxide and unburned hydrocarbons [71]. Abdalkarim and coworkers prepared biodegradable dipole responsive magnetic/solar-driven PCF composites reinforced with magnetic cellulose nanocrystals hybrids (MCNC) [72]. The PCF/MCNC composites showed enhanced latent heat phase change enthalpies, thermal stability, and increased magnetic/solar-driven thermal energy storage efficiencies. The authors also reported the potential of PCF/MCNC composites for drying and preservation of agriculture products, including fruits [72].

Shaheen *et al*. synthesized nanocomposites of molybdenum and zinc oxide [MoO3@ZnO] via chemosynthetic and biomimetic routes and showed a direct bandgap of 4.5 and 3.5 eV, respectively [73]. They demonstrated the semi-conducting and capacitive properties of the biogenic nanocomposite using electrochemical studies included cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) suitable for applications in solar cells [73]. Aziz and coworkers fabricated a methylcellulose: dextran (MC: Dex) polymer blend-based electrolyte system with ammonium iodide (NH4I) salt for electrical double-layer capacitor (EDLC) application [74]. The electrolyte system was ionic in nature and showed the maximum ionic conductivity as 1.12 × 10−3 S/cm with an electrochemical stability window of 1.27 V. The EDLC device offered an initial specific capacitance of 79 F/g, an energy density of 8.81 Wh/kg and power density of 1111.0 W/kg at a current density of 0.2 mA/cm2 [74]. Youssef *et al*. prepared the conducting bionanocomposite hydrogels using chitosan (CS)/hydroxyl ethylcellulose (HEC)/polyaniline (PAni) loaded with graphene oxide (GO) doped by silver (Ag) nanoparticles as a semiconductor material for electrical storage devices [75]. CS/HEC/PAni/GO@Ag bionanocomposite hydrogels exhibited improved swelling percentage, capacitance, permittivity, antibacterial activities, and biodegradation properties. The bionanocomposite displayed the highest dc-conductivity of 8.53 x 10−2 S/cm [75].

#### **4.3 Environmental remediation**

The rapid industrialization and urbanization across the globe have significantly impacted the terrestrial and aquatic environments by releasing harmful industrial effluents, including colored organic dyes, heavy metals, polycyclic aromatic hydrocarbons (PHAs), chlorinated organics and perfluorosurfactants [76]. The release of these toxic substances imposes serious health concerns on all living beings. Biodegradable nanomaterials have recently been considered highly efficient agents for environmental remediation due to their high chemical reactivity, surface properties, catalytic activity, easy synthesis and fabrication, and environmental benignity. This section covers the applications of biodegradable nanoparticles in environmental remediation.

#### *Novel Acumens into Biodegradation: Impact of Nanomaterials and Their Contribution DOI: http://dx.doi.org/10.5772/intechopen.98771*

Rajeswari *et al*. reported the synthesis of biodegradable mixed matrix membranes (MMMs) using aluminum oxide (Al2O3) and nano zerovalent iron (nZVI) nanoparticles blended cellulose acetate-polysulfone (CA-PSF) for the removal of methylene blue (MB) dye and Cu (II) metal ions [77]. The authors reported the rejection values 91 and 94% for MB dye and for Cu (II) the rejection values of 84 and 88% using CA-PSF/Al2O3 and CA-PSF/nZVI membranes [77]. Pandey and coworkers fabricated slow-release microencapsulated zerovalent iron nanoparticles (ZVINPs) in polylactic acid (PLA)-based microparticles for in-situ groundwater remediation of hydrophilic (methyl orange dye) and hydrophobic (trichloroethylene) water contaminants by electrospraying technique [78]. The authors reported that approximately 8 wt% ZVINPs were slowly released from the biodegradable microparticles after 60 h and 32 h incubation to fully remediate methyl orange (25 mg/L) and trichloroethylene (0.2 vol%) from water, respectively [78]. The photocatalytic properties of Mg-doped ZnO nano-semiconductors for the decontamination of non-treated laundry wastewater were investigated by Oliveira *et al.* [79]. The authors showed the degrading of approximately 53% of pollutants after 240 min of UV–vis irradiation, reducing 31% in total organic carbon (TOC). The treated laundry wastewater promoted the growth of cucumber seeds and tomato roots [79].

Electrospun and thermally cross-linked poly(vinyl alcohol) (PVA) and konjac glucomannan (KGM)-based biodegradable nanofiber membranes loaded with zinc oxide (ZnO) nanoparticles were prepared by Lv *et al*. [80]. ZnO@PVA/KGM membranes exhibited photocatalytic decolorization of methyl orange dye (20 mg L − 1) with a removal efficiency of over 98% under 120 min of solar irradiation. They also investigated efficient air-filtration and antibacterial performances for the ZnO@ PVA/KGM membranes [80]. **Figure 2(A)**–**(D)** shows the schematic presentation of the preparation of the ZnO@PVA/KGM membranes by electrospinning, air filtration process, Photocatalytic degradation, and (D) antibacterial activity of the membranes [80]. Barbosa and coworkers prepared the biodegradable poly(butylene adipate-co-terephthalate) membranes functionalized with cellulose nanoparticles

#### **Figure 2.**

*Schematic representation of the (A) preparation, (B) air filtration process, (C) photocatalytic degradation, and (D) antibacterial activity of the biodegradable ZnO@PVA/KGM nanofiber membranes [80].*

(CNS) via phase inversion technique for the removal of chromium (Cr) ions from contaminated drinking water [81]. The CNS functionalized membranes that were subjected to phosphorylation (CNS-P) displayed the removal of 93% and 88% of Cr(VI) and Cr(III), respectively, showing their application in domestic houses and water treatment stations [81].

#### **4.4 Nanomedicine**

Biodegradable nanomaterials have been recently investigated in nanomedicine due to their controlled drug release and targeted drug delivery, giving enhanced therapeutic effects and reduced side effects. Biodegradable nanomaterials impose less cytotoxicity on cells. Due to modifying and functionalizing ability, the biodegradable nanoparticles can also improve drug stability and solubility. The vital applications of biodegradable nanoparticles in nanomedicine include drug delivery, cancer therapy, imaging, and antimicrobial activity.

Far *et al*. synthesized biodegradable poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) loaded with mometasone furoate (MF) using the nanoprecipitation method [82]. They reported the controlled release of MF using PLGA NPs over 7 days in vitro with an initial burst release, demonstrating therapeutic potential in nasal delivery applications [82]. Gai and coworkers developed a drug delivery system (DDS) for rheumatoid arthritis (RA) therapy using benzoylaconitine (BAC) encapsulated methoxy-poly (ethylene glycol)-poly(lactide-co-glycolide) (mPEG-PLGA) nanoparticles (NPs) via hydrophobic interaction [83]. The mPEG-PLGA NPs (NP/BAC) system exhibited low cytotoxicity and good biocompatibility for lipopolysaccharide (LPS)-activated macrophages and efficient in vivo anti-inflammatory effect with the high ear (69.8%) and paw (87.1%) swelling suppressing rate. The authors mentioned the possible application of biodegradable NP/BAC system in anti-inflammation and RA therapy as an effective DDS [83].

Qin *et al*. reported the synthesis of tumor-sensitive biodegradable nanoparticles using fluorescent zeolitic imidazolate framework-8 nanoparticles loaded with doxorubicin (FZIF-8/DOX) as the core and a molecularly imprinted polymer (MIP) as the shell (FZIF-8/DOX-MIPs) [84]. FZIF-8/DOX-MIPs showed an inhibitory effect on the growth of MCF-7 tumors and served as a diagnostic agent giving stronger red fluorescence at the tumor sites [84]. A pH-sensitive biodegradable garcinol (GAR)-loaded poly (lactic–co–glycolic acid) (PLGA) coated with Eudragit® S100 (ES100) (GAR-PLGA-ES100 nanoparticles (NPs)) was designed for reducing inflammation caused by pro-inflammatory cytokines in the gastrointestinal tract [85], see **Figure 3**. The authors reported the site-directed release of the drug specifically from NPs at the colonic pH of 7.4, reducing the activation of inflammation that leads to inflammatory bowel disease (IBD) [85].

Han *et al*. developed hypericin encapsulated methoxy poly(ethylene glycol) b-poly(ε-caprolactone) (PEG-PCL) biodegradable nanoparticles (Hyp-NP) with necrosis affinity and fluorescence imaging in vitro and in vivo [86]. The authors showed the cellular internalization with intracellular cytoplasmic localization and preserved fluorescence and necrosis affinity for Hyp-NPs, suggesting their potential applications in tumor imaging and therapy [86]. Fernández-Gutiérrez and coworkers reported the fabrication of a biocomposite polymeric system for the antibacterial coating of polypropylene mesh materials for hernia repair [87]. **Figure 4(a)**–**(d)** shows the microscopic and scanning electron microscopic (SEM) images of the meshes with different coatings. The antibacterial coating was performed by a film of chitosan containing poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles loaded with antibiotic (rifampicin) or an antiseptic (chlorhexidine). Both biocomposite coatings exhibited antibacterial activity and cell compatibility, offering a potential strategy to protect meshes from bacterial adhesion following implantation [87].

*Novel Acumens into Biodegradation: Impact of Nanomaterials and Their Contribution DOI: http://dx.doi.org/10.5772/intechopen.98771*

#### **Figure 3.**

*SEM image of the biodegradable GAR-PLGA-ES100 NPs (At scale 3.00 μm) [85].*

#### **Figure 4.**

*Macroscopic pictures and SEM micrographs of different meshes (a) nude control (chitosan only), (b) coated with the unloaded biocomposite (chitosan-PLGA), (c) coated with chlorhexidine (CHX)-loaded biocomposite (chitosan-PLGA-CHX), and (d) coated with the rifampicin (RIF)-loaded biocomposite (chitosan-PLG-RIF) [87].*

## **5. Conclusions**

Biodegradation is the naturally occurring degradation of complex substances into simple eco-friendly products by the action of microorganisms and plays an imperative role in sustainable development. One of the significant challenges of biodegradation includes the incomplete breakdown of materials due to the complexity of the materials arising from structure, molecular weight, crosslinking, shape, texture, and surface properties. Other setbacks include the screening and identifying of suitable microbes, nutrients, and environmental conditions.

### *Biodegradation Technology of Organic and Inorganic Pollutants*

Nanotechnology integrated biodegradation process has recently become an ecofriendly and cost-effective method of diminishing environmental pollutants due to the synergetic effects. The factors including the type of nanomaterials, type of the microorganism, and culture medium directly affect the involvement of nanomaterials in biodegradation. Common types of nanomaterials utilized in biodegradation processes include zero valent metals, oxides, sulfides, nanocomposites, nanoclay, carbon materials, biopolymers, and nanofibers. Biodegradable nanomaterials have been widely applied in food packaging, energy, environmental remediation and nanomedicine.
