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Due to their great physical and mechanical behaviors, polymers have become essential in various industries. Polymers have been produced using chemical monomer synthesis, potentially dangerous non-biodegradable waste in the environment. Therefore, biopolymers are introduced, and organic compounds are found in natural sources as monomeric units. Also, biopolymers were discovered to be biodegradable and biocompatible, and these biopolymers are beneficial in numerous applications. Natural plant fibers have drawn more attention recently as potential reinforcing materials. The composites made with natural fibers have excellent mechanical and thermal characteristics. Materials made of natural fibers are inexpensive, recyclable, and environmentally beneficial. These natural fibers are excellent candidates to replace conventional fibers due to their biodegradability and eco-friendliness. The adhesion between the fibers and matrix has the most impact on the mechanical characteristics of composites. The mechanical characteristics of the composites were improved by combining chemical and physical modification techniques to increase fiber–matrix adhesion. The main objective of this study is to provide a thorough understanding of common types of biopolymers, various natural fibers, fillers, chemical treatments, and the performance of biopolymers and their composites-reinforced natural fibers. Moreover, the characterization and application of various biopolymers and composites were reviewed.

This work presents a comparative study of a series of Fe–Mn–Si alloys proposed as degradable biomaterials for medical applications. Five Fe-28wt.%Mn-xSi (where x = 0 to 8 wt.%) alloys were fabricated by an arc-melting method. All the as-cast alloys were subsequently subjected to homogenization treatment and hot forging. The microstructure and phase constituents were investigated. It is found that the grain size of the as-forged alloys ranged approximately from 30 to 50 μm. The as-forged Fe–Mn–Si alloys containing Si from 2 to 6 wt.% was comprised of duplex martensitic ε and austenitic γ phases; however, the Si-free and 8 wt.% Si alloys only consisted of a single γ phase. After 30 days of static immersion test in a simulated body fluid (SBF) medium, it is found that pitting and general corrosion occur on the sample surfaces. Potentiodynamic analysis reveals that the degradation rate of the Fe–Mn–Si alloys increased gradually with Si content up to 6 wt.%, beyond which the degradation slows down.

This study is a pilot investigation on the effect of using nanosilica for reinforcing thermoplastic starch-based bioplastic films. An arbitrary 0.2wt.% of nanosilica particles were used to reinforce starch derived bioplastic materials and were further investigated for potential benefits. Nanosilica was extracted from rice husk and was characterized using methods like Fourier transform infrared spectroscopy (FTIR) technique and Brunauer–Emmett–Teller (BET) method. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques were used to determine the structure of nanosilica crystals. Scanning electron microscopy (SEM) technique was used to study the surface topography and composition of nano ‘silica. Both raw and reinforced bioplastic films were tested for thermal stability using thermo gravimetric analysis (TGA) and differential scanning calorimetry (DSC) tests and their performance was compared. Mechanical properties were compared using tensile and tear tests and biodegradability was assessed through enzymatic degradation analysis. It was found that the presence of nanosilica improved the bonding of polymer matrix and in turn increased the thermal stability and tear strength. Nanosilica reinforced matrix resulted in the increase of surface area than raw bioplastic matrix, which lead to high rate of enzymatic reactivity and degradation rate.

This work aimed at synthesizing the chitosan-based nanocomposite for concurrent diagnosis of colon tumors and targeted drug shipping with minimum toxicity. CuO-chitosan nanocomposite was developed using CuO nanoparticles (NPs), chitosan raw materials and 1% acetic acid. FE-SEM/EDX, TEM, XRD, DLSUV-Vis, FT-IR, as well as fluorescent emission spectrum methods were used to investigate the characteristics of nanocomposite gained throughout distinct levels. Bovine serum albumin (BSA) protein release rate was estimated. We investigated the antibacterial functioning of the nanocomposite against different bacteria types (like S. aureus, S. typhi, E. coli, L. monocytogene and P. aeruginosa), which can affect in causing tense colonic diseases. Qualitative and quantitative surveys were performed. The impact of the nanocomposite on cancerous and normal human colon cell lines, specifically HCT-116 and SW-948, was examined using the MTT assay. Eventually, loading BSA onto the CuO–chitosan nanocomposite enhances its potential as a drug carrier for treating colon cancer, causing minimal harm to surrounding normal cells. Additionally, the CuO-chitosan nanocomposite demonstrated significant antibacterial activity against Escherichia coli, a key pathogen associated with Crohn’s disease and ulcerative colitis.

A new method to synthesize a degradable terminal amino group-containing copolymer, poly(ethylene glycol)-b-poly(ε-caprolactone) (MPEG-PCL-NH₂), was developed in the following three steps: (1) the ring-opening polymerization (ROP) of ε-caprolactone from the Schiff base prepared from benzaldehyde and ethanolamine (Ph–CH=NCH₂CH₂OH) used as an initiator to obtain heterobifunctional poly(ε-caprolactone) with one terminal Schiff base group and one hydroxyl group (HO-PCL-CH₂CH₂N=CH–Ph); (2) the coupling reaction of two reactive precursors, a hydroxy-terminated HO-PCL-CH₂CH₂N=CH–Ph and α-monocarboxy-ω-monomethoxy poly(ethylene glycol) (CMPEG) to synthesize MPEG-PCL-CH₂CH₂N=CH–Ph; (3) the conversion of the –N=CH–Ph end-group into NH₂ end-group by acidification of acetic acid to obtain MPEG-PCL-NH₂. The structures from the precursors to the terminal amino group-containing copolymer were confirmed by ¹H-NMR and their molecular weights were measured by gel permeation chromatography. The amphiphilic terminal amino group-containing copolymer could self-assemble into micelles in an aqueous system with PCL block as the core and PEG block as the shell. The micelle formation of the terminal amino group-containing block copolymer was studied by fluorescent probe technique and the existence of critical micellar concentration (cmc) confirmed the amphiphilic nature of the resulting copolymer. ESEM and DLS analysis of the micelles revealed a homogeneous spherical morphology and a unimodal size distribution.

Aggravating environmental problems have driven the unprecedented development of sustainable materials. Treatments of environmental pollutants with biomass-based sustainable materials are catching attention of more researchers. In the present work, a biomass-based strategy was developed to prepare sustainable molecularly imprinted nanocomposite membranes (S-MINMs). Based on this strategy, biomass-activated carbon nanoparticles (ACNPs) as the porous filler were integrated into the porous cellulose acetate (CA)/chitosan (CS) hybrid membranes to synthesize renewable and easy degradable basal membranes. The specific recognition sites were fabricated from simple free radical polymerization method, and using methacrylic acid (MAA) and acrylamide (Am) as functional monomers, we obtain improved adsorption capacity on tetracycline (TC, template molecule). Performance of S-MINMs was evaluated by adsorption isotherm, adsorption kinetics, perm-selectivity, reusability and biodegradability. Results indicated that the as-prepared S-MINMs not only exhibited desirable biodegradability, but also possess superior adsorption and separation performance toward TC (15.99mg g${}^{-1}$ for adsorption capacity and 4.91 for perms-selectivity factor). The method developed here shows great potential for development of sustainable membranes for selective separation of various pollutants.

The biodegradability of inorganic nanocarriers is one of the most critical issues in their further clinical translations. In this work, a manganese-doped approach was developed to endow inorganic mesoporous silica (SiO₂) nanospheres with pH-sensitive biodegradation. Manganese-doped mesoporous silica nanospheres (MMS) were prepared by in-situ doping method, with a particle diameter of 160–175 nm and pore diameter of 3–5nm by characterization of N₂ adsorption method, powder X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectrum, field emission scanning electron microscope and transmission electron microscope techniques. Quercetin was used as the model drug to load, and MMS loaded with quercetin (MMS–QUE) was surface-modified using a carboxymethyl chitosan (MMS–QUE–CMCS) to prevent quercetin leakage. Based on the dissolution characteristics of manganese ions and the swelling behavior of carboxymethyl chitosan, the MMS–QUE–CMCS could be degraded in response to acid. The MMS–QUE–CMCS delivery system exhibited a good pH-responsive release. The cytotoxicity test showed that the MMS–QUE–CMCS had a significant biocompatibility and an enhanced cytotoxicity, thus revealing that the MMS–QUE–CMCS was a promising delivery system.

To integrate pH/NIR dual-responsive drug release mechanisms with multimodal therapies for effective treatment of malignant tumors, hierarchical hydroxyapatite (HAp)/AuNR hybrid microspheres, consisting of a hollow HAp core and an AuNR shell, were facilely synthesized using phytic acid (IP6) as a sustainable template and phosphorus source. Urea served as the pore-forming agent and pH regulator during the synthesis process. The integration of AuNR into multifunctional HAp systems enabled NIR-responsive controllable drug release and photothermal ablation specifically at the tumorigenic site. The aggregation of AuNR within and outside the hybrid microspheres effectively hinders the release of doxorubicin hydrochloride (DOX) from the hollow HAp microspheres, mitigating the initial burst release and minimizing side effects. The results indicate that the h-HAp/AuNR hybrid exhibited remarkable drug loading efficiency (159.9$\mu$g ⋅ mg${}^{-1}$), with drug release exhibiting pH-dependent behavior due to the dissolution of HAp in acidic environments. Furthermore, MTT assays and fluorescence imaging demonstrate that DOX-loaded h-HAp/AuNR significantly enhance antitumor efficacy, achieving a cell survival rate of 12.3% at a concentration of 100$\mu$g ⋅ mL. This integrated system offers a promising approach for combined chemotherapeutic delivery and NIR photothermal therapy.

Biodegradable stenting and implantation materials have received considerable attention in biomaterials community, with magnesium having been received most wide attention. However, magnesium corrodes too fast by nature, in human body environment. A new type of biodegradable metal – Fe and its alloys – has been introduced in recent years. In this study, a Fe35wt%Mn alloy was produced using powder sintering. Powder mixture was mechanically milled, pressed and then sintered to consolidate powder compacts. Microstructure characterization and hardness measurement were carried out on the as-sintered samples. In vitro degradability evaluation of the samples was performed in 5% NaCl and Simulated Body Fluid (SBF) media. The experimental results show that a higher porosity results in a higher degradation rate. All samples, with porosity being from 6.5% to 12.2 %, revealed a degradation rate from 0.6 to 1.4 mm/year.

In recent years, the shift toward renewable materials has been driven by the environmental and economic implications of synthetic alternatives. Bio-filler reinforced polymer composites, particularly our Date seed and Acacia filler reinforced vinyl ester (DSF/AF-VE), provide multifaceted advantages like ecological sustainability, cost-effectiveness, biocompatibility, reduced carbon footprint, and enhanced processability for diverse applications, including automotive components, biodegradable packaging, and lightweight construction materials. This study explores using Date seed and Acacia fillers, known for their sustainability, recyclability, and bio-degradability, in polymer composites. By incorporating these fillers with vinyl ester, we aimed to enhance properties like mechanical strength, thermal stability, and wear resistance. A standard compression molding process was chosen for this experiment due to its proven effectiveness in achieving uniform filler distribution, reproducibility of composite properties, and its suitability for large-scale industrial applications. DSF/AF-VE composites were produced with filler loadings ranging from 10% to 40%, maintaining a 50% filler/filler ratio. Our findings indicate that an optimal filler proportion significantly enhances the structural properties of the composite. A filler concentration of 15w% yielded the best tensile and flexural strength, while 20w% was optimal for impact strength. The DSF/AF-VE hybrid filler showed considerable improvements in tensile, flexural, and impact strength compared to the clear matrix, with increases of 1.53 times, 1.48 times, and 1.93 times, respectively. This study underscores the potential of Date seed and Acacia fillers in enhancing the mechanical properties of natural polymer composites, suggesting their suitability for low-load applications, such as switchboards, panels, wheel arches, and air spoilers.

Surfactants are among the most abundant, man-made organic pollutants with a high potential to enter the environment through the discharge of domestic and industrial wastewater as well as sewage sludge. Due to their amphiphilic structure, they not only are present in natural waters at concentrations varying between nondetectable to several μg/L's, but also tend to significantly sorb onto sewage sludge, ultimately bioaccumulating in soil sediments of receiving water bodies. According to extensive biodegradability and ecotoxicological studies, most surfactants are readily biodegradable regarding the parent compound; however complete oxidation is usually achieved neither in engineered treatment systems nor in the natural environment. In addition, acute toxicity data reveal that most surfactants are fairly toxic toward aquatic as well as terrestrial organisms. Considering these facts, treatment with alternative, advanced oxidation processes (AOPs) could be a promising option to alleviate the problem of uncontrolled bioaccumulation and biodegradation of surfactants in the environment. The present work reviews the application of chemical and photochemical AOPs for the detoxification and mineralization of commercial surfactant formulations. Special emphasis has been given to the main limitations of advanced oxidative treatment applications, namely toxicity of advanced oxidation intermediates/end products.

The developments of nanoscience and medicine have created the opportunities for the nanomaterials’ medicial applications. More and more materials were used in the medical field in recent years. For nanostructures, biocompatibility and biodegradability are the two most important characters when used in biological and medical fields, such as wound healing, tissue reconstruction and controlled drug delivery etc. In this chapter, we focused on studies of several biocompatible and biodegradable nanostructures used in medical and biological fields. We also reviewed degradable biomaterials, including natural and synthetic materials. The potential applications of these biocompatible and biodegradable nanostructures in the medical field were also analyzed.

The object of this research was to evaluate biodegradability of various organic waste in anaerobic digestion(AD). Slaughterhouse by-production and sludge, sewage sludge, animal manure and food waste has been used in this study. C/N ratio was used to estimate and to enhance the efficiency of AD. The highest biodegradability was appeared from food waste as 92.14%, and the lowest was shown from animal manure as 15.34%. Cattle rumen content showed highest C/N ratio (19.2), however, biodegradability was low as 34.02%.