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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.

Nanodiamonds (NDs) have unique optical and mechanical characteristics, surface chemistry, extensive surface area and biocompatibility, and they are nontoxic, rendering them suitable for a diverse range of applications. Recently, NDs have received significant attention in nano-biomedical engineering. This review discusses the recent advancement of NDs’ biomedical engineering, historical background, basic introduction to nanoparticles and development. We summarize NDs’ synthesis technique, properties and applications. Two methodologies are used in ND synthesis: bottom-up and top-down. We cover synthesis methods, including detonation, ball milling, laser ablation, chemical vapor deposition (CVD) and high pressure and high temperature (HPHT); discuss the properties of NDs, such as fluorescence and biocompatibility. Due to these properties, NDs have potential applications in biomedical engineering, including bioimaging, biosensing, drug delivery, tissue engineering and protein mimics. Further, it provides an outlook for future progress, development and application of NDs in biological and biomedical areas.

In metal-cutting operations, the surface roughness of the end product plays a significant role. It not only affects the aesthetic appearance of the end product but also signifies the product’s performance in the long run. Products with a high surface finish have higher endurance limits with negligible local stresses. On the other hand, products with rough surfaces are subjected to high stresses when they are engaged in various mechanical operations with varying loads. Surface roughness depends on various machining factors such as feed rate, depth of cut, cutting speed, or spindle speed. Therefore, it is required to predict surface roughness for the given machining parameters to reduce the cost and increase the life of the end product. In this work, an attempt has been made to evaluate the surface roughness of AZ91 alloy during the end milling operation. In this regard, various state-of-the-art ensemble learning models have been adopted and compared with the proposed hybrid ensemble model. The proposed hybrid ensemble model is the integration of random forest, gradient boosting, and a deep multi-layered neural network. In order to evaluate the performance of the proposed model, comparative analyses have been made in terms of mean square error, mean average error, and $R^2$ score. The result shows that the proposed hybrid model gives minimum error for surface roughness.

50-nm diameter halloysite clay nanotubules with 15 nm lumen were used for loading poorly soluble drugs and sustaining their release. Loading was optimized by varying pH and alcohol/water ratio in the solvent with a maximum drug loading of 12 volume%. Near linear release of Dexamethasone, Furosemide, and Nifedipine was demonstrated for 5–10 hours. Its capacity for the time release of drugs, along with its simple loading procedure and the biocompatibility of halloysite nanotubules makes this method a prospective drug delivery system.

The green synthesis of gold nanoparticles (Au NPs) for catalytic and biological applications has been drawing great attention. To compare with plant extracts, the polysaccharides may be good reducing and stabilizing agents. In this work, we describe the preparation of longan polysaccharide stabilized gold nanoparticles (Au_n-LP NPs) by reduction of gold ions using a green synthetic method. The formation of gold nanoparticles (Au NPs) was confirmed by UV-Vis spectra. TEM showed that Au NPs had a small size (7.8–15.6nm) and were highly dispersed without any aggregation. XPS confirmed that the surface elemental composition of Au_n-LP NPs was C, O, and Au. DLS demonstrated that Au_n-LP NPs had good stability and negative zeta potential. In addition, Au_n-LP NPs had high catalytic activity for the reduction of 4-nitrophenol. More importantly, Au_n-LP NPs had ignorable cytotoxicity towards HeLa cells and showed good antioxidant activity. Taken together, the results indicated that longan polysaccharide can be used as reducing agents and stabilizers for the preparation of metallic nanoparticles, and the product had wide applications.

Hydroxyapatite (HA) is a highly biocompatible material that has similar properties to human bone. Researchers have adopted different methods for the synthesis of HA from different natural sources. This paper addresses the synthesis method of nano-hydroxyapatite (n-HA) from Hilsha Fishbone. The synthesized n-HA has been characterized by UV, FTIR, TEM, XRD and cytotoxicity analysis. The successful synthesis of n-HA has been confirmed by the peak formation in the UV analysis. The presence of functional groups has been identified by the FTIR analysis. According to the TEM images, the synthesized n-HA is irregular in size and shape. Based on the XRD analysis, the formation of crystals by the n-HA has been assured. The in-vitro cytotoxicity analysis confirmed the bio-safety of the synthesized n-HA. Based on the findings, the synthesized n-HA can be applied in different biomedical applications.

Optical imaging uses nonionizing radiation to obtain images of tissues and cells inside the body. The approach reduces exposure to harmful radiation and is suitable for lengthy and repetitive imaging procedures. Development of strongly fluorescent imaging agents will help in the detection of signal through thick tissues. Presence of such biocompatible imaging agent has potential clinical applications as it gives real-time information on disease progression and therapeutic response. We report here a nanoformulation-based strategy to synthesize a strongly fluorescent imaging agent. The fabrication procedure uses silica nanocapsules (SNC) to trap and concentrate highly fluorescent Coumarin 545T fluorophore. Biocompatibility of synthesized SNC–Coumarin was tested in cell lines and zebrafish. In vivo detection of fluorescent signal was validated in optically translucent zebrafish larvae and adult casper mutant. Nonbiased labeling of all cell types was detected in both young and adult zebrafish. The ability to differentiate fluid filled cavities from cells was also highlighted during in vivo imaging. Concomitant assessment of internalized SNC–Coumarin through acquired fluorescent intensity and associated biocompatibility in zebrafish supports its use as an in vivo imaging agent.

In this nano era, biomaterials associated infection is a serious problem in the biomedical arena. The race between microbial adhesion and tissue integration becomes a major cause of concern, during the implantation process. Microbial adhesion further gives rise to biofilm formation which finally leads to implant failure. We have therefore designed a strategy to fight effectively against the encroachment of Staphylococcus aureus biofilm, which is chiefly responsible for majority of biomaterials associated infections. Silver nanoparticles have been synthesized for the purpose using foliage needles of the plant Pseudotsuga menziesii, our Christmas tree. Thereafter the nanoparticles were dispersed in chitosan, a biopolymer matrix and a bionanocomposite, self-sterilizing coating biomaterial was developed. The silver nanoparticles produced, the bionanocomposite developed, and the coating over medical implant, have been characterized through various techniques. The efficacy of the silver/chitosan bionanocomposite, against S. aureus biofilm has been studied here, after being coated over medical implant. It was found that coating of medical implants with this material can definitely restrict bacterial adhesion and their subsequent biofilm formation. This biomaterial was found to be blood and biocompatible at specific levels through testing.

The application of biodegradable and biocompatible polymer composite is continuously increasing in various fields such as electrical, electronics, construction, automobiles, and aerospace. The synthetic petroleum-based polymers and composite materials are the cause of the accumulation of huge quantities of waste and subsequently affect our natural ecosystem seriously. Hence, to solve this global issue, researchers are focusing on the development of new sustainable, biodegradable polymeric materials, which are cost-effective and easily industrialized to substitute the conventionally used nonbiodegradable polymeric materials. For proper development and design of biodegradable and biocompatible polymer nanocomposite, different behaviors of the prepared materials must be studied. The viscosity and shear modulus of polymer nanocomposites (PNCs) is the product of viscosity or the dynamic shear modulus of the matrix phase of the nanocomposite and volume fraction of the particle. The viscoelastic behavior of the PNCs is strongly influenced by the properties of the polymer matrix and nanoparticle interactions. The different thermomechanical behaviors of polymer and biopolymers include abrasion, thermal shock, mechanical stresses, coefficient of thermal expansion, thermomechanical analysis, thermal stability, $T_g$, thermal expansion, thermal analysis, etc. The biodegradable and biocompatible polymeric materials do not possess adequate thermomechanical properties, therefore, to improve the thermomechanical properties, the material should be blended with other suitable materials. Some of the biocomposite materials such as PLA/PBAT, PLA/PBSA, PLA/PBSA, PLA nanocomposites reinforced with clay materials and some fiber-reinforced polymer composites exhibits good thermomechanical properties.