Spatiotemporal Magnetocaloric Microenvironment for Guiding the Fate of Biodegradable Polymer Implants

The degradation behavior of implants is significantly important for bone repair. However, it is still unprocurable to spatiotemporally regulate the degradation of the implants to match bone ingrowth. In this paper, a magneto-controlled biodegradation model is established to explore the degradation behavior of magnetic scaffolds in a magnetothermal microenvironment generated by an alternating magnetic field (AMF). The results demonstrate that the scaffolds can be heated by magnetic nanoparticles (NPs) under AMF, which dramatically accelerated scaffold degradation. Especially, magnetic NPs modified by oleic acid with a better interface compatibility exhibit a greater heating efficiency to further facilitate the degradation. Furthermore, the molecular dynamics simulations reveal that the enhanced motion correlation between magnetic NPs and polymer matrix can accelerate the energy transfer. As a proof-of-concept, the feasibility of magneto-controlled degradation for implants is demonstrated, and an optimizing strategy for better heating efficiency of nanomaterials is provided, which may have great instructive significance for clinical medicine.     

Deduction of a facile method to construct Antheraea mylitta silk fibroin/gelatin blend films for prospective biomedical applications

Blend films of two types (I and II) were prepared by mixing Antheraea mylitta silk fibroin (AMF) and gelatin solution in various blend ratios via the solution casting method. Two different crosslinkers, namely glutaraldehyde and genipin, were used during blend preparation. The structural characteristics and thermal properties of the blend films were examined by Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), Thermogravimetric analysis (TGA) and Diffrential scanning calorimetery (DSC). The FTIR spectra showed conformational alterations in type I blend films while type II films attained high β‐sheet crystallinity. The XRD diffractograms presented a high degree of crystallinity in type II blend films compared to type I, which showed an almost amorphous structure. Further, thermal and biological studies were conducted on type II films. According to the TGA thermograms, the degradation temperature of the crosslinked blend films shifted compared to pure gelatin and pure AMF films. Partial miscibility of the two components was indicated by DSC thermograms of the blends. The high water uptake capacity of type II blend films was found to imitate hydrogel behaviour. The blend films did not show any toxicity in 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide (MTT) assay and supported L929 fibroblast cell spreading and proliferation. The biodegradation of the blend films was significantly faster than the pure silk film. © 2020 Society of Industrial Chemistry     

Modification of the wood-plastic composite for enhancement of formaldehyde clearance and the 3D printing application

As the formaldehyde is one of the main indoor pollutants, the purpose of this study is to effectively remove indoor formaldehyde pollution by using environmentally friendly 3D printing ornaments. The wood 3D printing filaments cellulose/polylactic acid composite (Cellu/P) was selected as the starting material, and 3-aminopropyltriethoxysilane (APTES) was used for chemical modification to obtain a series of cellulose composite materials with amino groups. The modified composite materials (APTES@Cellu/P) were characterized by Fourier transform infrared, X-ray diffraction, scanning electron microscope, energy dispersive spectroscopy, thermogravimetric analysis, and mechanical tests, and a formaldehyde removal experiment was performed. The feasibility of 3D printing was evaluated, and the process of 3D printing-functionalized customized ornaments was proposed, and then a school emblem was used for modeling, printing, and surface modification. Compared with the commercially traditional activated carbon, 3D printing-customized ornaments of APTES@Cellu/P material has a better formaldehyde removal effect, and can even avoid the secondary pollution that is common to the activated carbon.     

Biodegradation of poly(lactic acid)—cassava bagasse composites produced by injection molding

Neat poly (lactic acid) (PLA) and PLA/cassava bagasse (CB) composites were used to produce seedling tubes by extrusion and injection molding. The tubes were buried in simulated soil, and their biodegradation was investigated by weight loss, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). After 180 days, the composites' biodegradation was higher than neat PLA material, and the higher the CB content, the higher the biodegradation, which caused fissures and voids in the material. The biodegradation of PLA/CB composites increased the phosphorus content in the soil after 180 days. Composites of PLA with CB, an abundant agro-industrial residue in Brazil, are promising because they can reduce the environmental impact due to CB's proper destination, and the composites' costs and biodegradation are faster than pure PLA material. Both the faster biodegradation of the tube and the higher P content are advantageous for seedling tubes.     

Genipin-crosslinking polyvinyl alcohol hollow braids degradable tissue engineering scaffolds: Manufacturing techniques and property evaluations

Tissue engineering has been developed with the aim of improving the regeneration and recovery of impaired tissues and organs. Biodegraded scaffolds serve the aforementioned functions and can also be decomposed by means of metabolism. They have no biological toxicity and save patients from injuries by the second surgery, which makes biodegradable scaffolds a new development trend in the tissue engineering. In this study, the textile engineering and chemical crosslinking techniques are employed to produce biodegradable polyvinyl alcohol (PVA) hollow braids, serving as the tissue engineering scaffolds. The process involves two types of products, including the twisted yarns and hollow braids. The twist number of PVA twisted yarns is changed to form different PVA twisted yarns, which are then used to braided into hollow braids via the braiding technology. Therefore, the hollow braids are basically composed three types of PVA twisted yarns. Next, the surface observation, mechanical properties, and degradation of the products are then evaluated. The test results indicate that PVA twisted yarns exhibit the optimal mechanical properties when being twisted with 3 turns/inch. Any higher twist counts result in over twist in the twisted yarns. The optimal hollow braids are composed of PVA twisted yarns with a twist counts being 3 turns/inch. Afterwards, hollow braids are crosslinking with genipin, thereby obtaining greater mechanical strength of 23.6 N and higher decomposition rate of 0.8. The specified hollow braids are suitable for the use as tissue engineering scaffolds.     

Crosslinked,biodegradable polyurethanes for precision-porous biomaterials: Synthesis and properties

Crosslinked poly(ester urethane)s and their acrylate derivatives based on trifunctional polycaprolactone and trifunctional aliphatic isocyanates were synthesized. Biodegradable scaffolds with uniform, controlled micron-scale porosity were fabricated with these materials. Mechanical and swelling properties of monolithic and microporous materials were studied. Cytotoxicity, hydrolytic, and enzymatic degradation and their effects on mechanical properties of the biodegradable scaffolds were investigated. The polymer degradation products were found not to be cytotoxic at moderate concentrations and to permit cell attachment and spreading. Degradation rates and mechanical properties could be tuned to desired performance criteria for a given application by adjusting crosslink density and the ratio of hard segment to soft segment. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48943.     

Enhanced impact strength of compatibilized poly(lactic acid)/polyamide 11 blends by a crosslinking agent

Maleated poly(lactic acid) (PLA-g-MA) was prepared through melt grafting of maleic anhydride onto a PLA backbone with the aid of a radical initiator. PLA-g-MA thus formed was incorporated into PLA/polyamide 11 (PA11) blends as a reactive compatibilizer. By morphological observation, it was assessed that PLA-g-MA lowered the interfacial energy and strengthened the interface between PLA and PA11. However, the compatibilized PLA/PA11 blends did not show significant improvement of impact strength compared with noncompatibilized PLA/PA11 blends. Measurements of the molecular weight and impact strength of PLAs compounded with various amounts of radical initiators revealed that decreased molecular weight of PLA by the radical initiator used for the preparation of PLA-g-MA is responsible for this unexpected result. To compensate the decrease of the molecular weight, a crosslinking agent was incorporated in the preparation step of PLA-g-MA. It was found that the crosslinking agent is effective in preventing the molecular weight reduction. As a result, the impact strength of the PLA/PA11 blend was enhanced to a great extent by the PLA-g-MA prepared with the crosslinking agent.     

Modification of thermoplastic polyurethane nanofiber membranes by in situ polydopamine coating for tissue engineering

To improve the interaction between cells and scaffolds, the appropriate surface chemical property is very important for tissue engineering scaffolds. In this work, the dopamine (DA) was first introduced into thermoplastic polyurethane (TPU) matrix to obtain TPU/DA nanofibers by electrospinning. Subsequently, the TPU@polydopamine (PDA) composite nanofibers with core/shell structure were fabricated by in situ polymerization of PDA. In comparison with TPU nanofibers, the uniformization of PDA coating layer on the surface of TPU/DA composite nanofibers significantly increased due to the addition of DA, which used as the active sites to guide the PDA particles accumulated along with the fiber direction. The hydrophilicity and water uptake ability of TPU@PDA composite nanofibers were larger than those of TPU nanofibers. The TPU@PDA composite nanofibers possess excellent comprehensive mechanical properties of high strength, stiffness, elasticity, and recoverability because of the hydrogen bonding occurrence between PDA and DA, as well as between PDA and TPU matrix. The attachment and viability of mouse embryonic osteoblasts cells (MC3T3-E1) cultured on TPU@PDA composite nanofibers were obviously enhanced compared with TPU nanofibers. Those results suggested that the modified TPU@PDA composite nanofibers have superior mechanical and biological properties, which promoting them potentially useful for tissue engineering scaffolds.     

Zein-based anti-browning cling wraps for fresh-cut apple slices

The usage of cling wraps is emerging as an easy and cost-effective approach to protect fresh-cut fruits and vegetables from dust, whilst improving visual appeal on retail counters. This study focused on developing an alternate, protein-based packaging material as a food grade cling wrap for food packaging applications. Zein-based cling wraps were produced, and their physical and mechanical characteristics were evaluated and compared with conventionally used chitosan biopolymer films and commercial synthetic polymer films. Antioxidant potential of the prepared films was studied, and the effectiveness of the developed films as anti-browning cling wraps was evaluated using studies conducted on fresh-cut apple slices at ambient conditions. Anti-browning effects were in par with polymeric counterparts; however, zein cling wraps could better prevent weight loss in apple slices. Zein-based films can be adopted as biodegradable food grade cling wraps as an alternative to chitosan and synthetic polymeric materials.     

Prospects of inedible plant oil-driven bio-lubricants for tribological characteristics – a review

ABSTRACT

Fossil fuel resource is on the draining stage which leads to an increment in the cost of the petroleum products. Nowadays, research is focused on the development of environmental friendly lubricants which are derivatives of renewable sources. Inedible plant oil-driven bio-lubricants are environmentally friendly because they are non-hazardous, biodegradable, as well as there is no emission of toxic gases. This study involves the characterisations, advantages, as well as utilisation of inedible plant oil-driven bio-lubricants as an alternative for tribological applications. This report presents the status about the global lubricant market as well as potential outlook. Inedible plant oil-driven bio-lubricants bear high viscosity, high lubricity, and high viscosity index which can enhance the equipment service life and has the ability to carry high load and results in minimum amount of metal traces during combustion.