Progress in hydroxyapatite-starch based sustainable biomaterials for biomedical bone substitution applications

Hydroxyapatite is a calcium phosphate intensively proposed as a bone substitution material because of its resemblance to the constituents of minerals present in natural bone. Since hydroxyapatite’s properties are mainly adequate for nonload bearing applications, different solutions are being tested for improving these properties and upgrading them near the target values of natural bone. On the other hand, starch (a natural and biodegradable polymer) and its blends with other polymers have been proposed as constituents in hydroxyapatite mixtures due to the adhesive, gelling, and swelling abilities of starch particles, useful in preparing well dispersed suspensions and consolidated ceramic bodies. This article presents the perspectives of incorporating starch and starch blends in hydroxyapatite materials. Based on the role of starch within the materials, the review covers its use as (i) a polymeric matrix in hydroxyapatite composites used as adhesives, bone cements, bone waxes, drug delivery devices or scaffolds and (ii) a sacrificial binder for fabrication of porous hydroxyapatite scaffolds. The suitability of these materials for bone reconstruction has becomes a reachable aim considering the recent advancements in ceramic fabrication and the current possibilities of controlling the processing parameters

Chapter 34 - Biocompatibility of nanocellulose: Emerging biomedical applications

Nanocellulose already proved to be a highly relevant material for biomedical applications, ensued by its outstanding mechanical properties and, more importantly, its biocompatibility. Nevertheless, despite their previous intensive research, a notable number of emerging applications are still being developed. Interestingly, this drive is not solely based on the nanocellulose features, but also heavily dependent on sustainability. The three core nanocelluloses encompass cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs), and bacterial nanocellulose (BNC). All these different types of nanocellulose display highly interesting biomedical properties per se, after modification and when used in composite formulations. Novel applications that use nanocellulose includewell-known areas, namely, wound dressings, implants, indwelling medical devices, scaffolds, and novel printed scaffolds. Their cytotoxicity and biocompatibility using recent methodologies are thoroughly analyzed to reinforce their near future applicability. By analyzing the pristine core nanocellulose, none display cytotoxicity. However, CNF has the highest potential to fail long-term biocompatibility since it tends to trigger inflammation. On the other hand, neverdried BNC displays a remarkable biocompatibility. Despite this, all nanocelluloses clearly represent a flag bearer of future superior biomaterials, being elite materials in the urgent replacement of our petrochemical dependence

Natural-origin materials for tissue engineering and regenerative medicine

Recent advances in tissue engineering and regenerative medicine have shown that combining biomaterials, cells, and bioactive molecules are important to promote the regeneration of damaged tissues or as therapeutic systems. Natural origin polymers have been used as matrices in such applications due to their biocompatibility and biodegradability. This article provides an up-to-date review on the most promising natural biopolymers, focused on polysaccharides and proteins, their properties and applications. Membranes, micro/nanoparticles, scaffolds, and hydrogels as biomimetic strategies for tissue engineering and processing are described, along with the use of bioactive molecules and growth factors to improve tissue regeneration potential. Finally, current biomedical applications are also presented.The authors would like to thank to the financial support from the Portuguese Foundation for Science and Technology (FCT) for the fellowship grants of Simone S Silva (SFRH/BPD/112140/2015), Emanuel M Fernandes (SFRH/BPD/96197/2013), Joana-Silva Correira (SFRH/BPD/100590/2014), Sandra Pina (SFRH/BPD/108763/2015), Silvia Vieira (SFRH/BD/102710/2014), “Fundo Social Europeu”- FSE and “ Programa Diferencial de Potencial Humano POPH”, and to the distinction attributed to J.M. Oliveira under the Investigator FCT program (IF/00423/2012). It is also greatly acknowledged the funds provided by FCT through the project EPIDisc (UTAP-EXPL/BBBECT/0050/2014), financed in the Framework of the “International Collaboratory for Emerging Technologies, CoLab”, UT Austin|Portugal Program.info:eu-repo/semantics/publishedVersio

Cellulose Nanofibers and Other Biopolymers for Biomedical Applications. A Review

Biopolymers are materials synthesised or derived from natural sources, such as plants, animals, microorganisms or any other living organism. The use of these polymers has grown significantly in recent years as industry shifts away from unsustainable fossil fuel resources and looks towards a softer and more sustainable environmental approach. This review article covers the main classes of biopolymers: Polysaccharides, proteins, microbial-derived and lignin. In addition, an overview of the leading biomedical applications of biopolymers is also provided, which includes tissue engineering, medical implants, wound dressings, and the delivery of bioactive molecules. The future clinical applications of biopolymers are vast, due to their inherent biocompatibility, biodegradability and low immunogenicity. All properties which their synthetic counterparts do not share

Approaches in biotechnological applications of natural polymers

Natural polymers, such as gums and mucilage, are biocompatible, cheap, easily available and non-toxic materials of native origin. These polymers are increasingly preferred over synthetic materials for industrial applications due to their intrinsic properties, as well as they are considered alternative sources of raw materials since they present characteristics of sustainability, biodegradability and biosafety. As definition, gums and mucilages are polysaccharides or complex carbohydrates consisting of one or more monosaccharides or their derivatives linked in bewildering variety of linkages and structures. Natural gums are considered polysaccharides naturally occurring in varieties of plant seeds and exudates, tree or shrub exudates, seaweed extracts, fungi, bacteria, and animal sources. Water-soluble gums, also known as hydrocolloids, are considered exudates and are pathological products; therefore, they do not form a part of cell wall. On the other hand, mucilages are part of cell and physiological products. It is important to highlight that gums represent the largest amounts of polymer materials derived from plants. Gums have enormously large and broad applications in both food and non-food industries, being commonly used as thickening, binding, emulsifying, suspending, stabilizing agents and matrices for drug release in pharmaceutical and cosmetic industries. In the food industry, their gelling properties and the ability to mold edible films and coatings are extensively studied. The use of gums depends on the intrinsic properties that they provide, often at costs below those of synthetic polymers. For upgrading the value of gums, they are being processed into various forms, including the most recent nanomaterials, for various biotechnological applications. Thus, the main natural polymers including galactomannans, cellulose, chitin, agar, carrageenan, alginate, cashew gum, pectin and starch, in addition to the current researches about them are reviewed in this article.. }To the Conselho Nacional de Desenvolvimento Cientfíico e Tecnológico (CNPq) for fellowships (LCBBC and MGCC) and the Coordenação de Aperfeiçoamento de Pessoal de Nvíel Superior (CAPES) (PBSA). This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit, the Project RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462) and COMPETE 2020 (POCI-01-0145-FEDER-006684) (JAT)

Manufacturing and Characterization of Functionalized Aliphatic Polyester from Poly(lactic acid) with Halloysite Nanotubes

[EN] This work reports the potential of poly(lactic acid)-PLA composites with different halloysite nanotube (HNTs) loading (3, 6 and 9 wt%) for further uses in advanced applications as HNTs could be used as carriers for active compounds for medicine, packaging and other sectors. This work focuses on the effect of HNTs on mechanical, thermal, thermomechanical and degradation of PLA composites with HNTs. These composites can be manufactured by conventional extrusion-compounding followed by injection molding. The obtained results indicate a slight decrease in tensile and flexural strength as well as in elongation at break, both properties related to material cohesion. On the contrary, the stiffness increases with the HNTs content. The tensile strength and modulus change from 64.6 MPa/2.1 GPa (neat PLA) to 57.7/2.3 GPa MPa for the composite with 9 wt% HNTs. The elongation at break decreases from 6.1% (neat PLA) down to a half for composites with 9 wt% HNTs. Regarding flexural properties, the flexural strength and modulus change from 116.1 MPa and 3.6 GPa respectively for neat PLA to values of 107.6 MPa and 3.9 GPa for the composite with 9 wt% HNTs. HNTs do not affect the glass transition temperature with invariable values of about 64 degrees C, or the melt peak temperature, while they move the cold crystallization process towards lower values, from 112.4 degrees C for neat PLA down to 105.4 degrees C for the composite containing 9 wt% HNTs. The water uptake has been assessed to study the influence of HNTs on the water saturation. HNTs contribute to increased hydrophilicity with a change in the asymptotic water uptake from 0.95% (neat PLA) up to 1.67% (PLA with 9 wt % HNTs) and the effect of HNTs on disintegration in controlled compost soil has been carried out to see the influence of HNTs on this process, which is a slight delay on it. These PLA-HNT composites show good balanced properties and could represent an interesting solution to develop active materials.This research was supported by the Ministry of Science, Innovation, and Universities (MICIU) through the MAT2017-84909-C2-2-R program number. D. Lascano wants to thank UPV for the grant received though the PAID-01-18 program. Microscopy services at UPV are acknowledged for their help in collecting and analyzing FESEM images.Montava-Jorda, S.; Chacon, V.; Lascano-Aimacaña, DS.; Sanchez-Nacher, L.; Montanes, N. (2019). Manufacturing and Characterization of Functionalized Aliphatic Polyester from Poly(lactic acid) with Halloysite Nanotubes. Polymers. 11(8):1-21. https://doi.org/10.3390/polym11081314S121118Andreeßen, C., & Steinbüchel, A. (2018). Recent developments in non-biodegradable biopolymers: Precursors, production processes, and future perspectives. 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Current Developments in 3D Bioprinting for Tissue and Organ Regeneration–A Review

Thefield of Tissue engineering and regenerative medicine that work toward creatingfunctional tissue-constructs mimicking native tissue for repair and/or replacement ofdamaged tissues or whole organs have evolved rapidly over the past few decades.However, traditional tissue engineering approaches comprising of scaffolds, growthfactors and cells showed limited success in fabrication of complex 3D shapes andinvivoorgan regeneration leading to their non-feasibility for clinical applications from alogistical and economical viewpoint. In this regard, 3D bioprinting, which is an extendedapplication of additive manufacturing is now being explored for tissue engineering andregenerative medicine as it involves the top-down approach of building the complex tissuein a layer by layer fashion, thereby producing precise geometries due to controlled nature ofmatter deposition with the help of anatomically accurate 3D models of the tissue generatedby computer graphics. Here, we aim to provide a comprehensive review of the 3Dbioprinting technology along with associated 3D bioprinting strategies including ink-jetprinting, extrusion printing, stereolithography and laser assisted bioprinting techniques.We then focus on the applications of 3D bioprinting technology on construction of variousrepresentative tissue and organs, including skin, cardiac, bone and cartilage etc. Wefurther attempt to highlight the steps involved in each of those tissues/organs printing anddiscuss on the associated technological requirements based on the available reports fromrecent literature. Wefinally conclude with current challenges with 3D bioprintingtechnology along with potential solution for future technological advancement ofefficient and cost-effective 3D bioprinting methods

Current Progress in Biopolymer-Based Bionanocomposites and Hybrid Materials

In recent years, the development of biopolymers based on constituents obtained from natural resources has been gaining considerable attention. The utilization of biopolymers to engineer advanced bionanocomposites and hybrid materials is the focus of increasing scientific activity, explained by growing environmental concerns and interest in the novel features and multiple functionalities of these macromolecules.In this Special Issue, we aim to present the current state of the art in research pertaining to biopolymer-based bionanocomposites and hybrid materials, and their advanced applications. Contributions on the processing of biopolymers and bionanocomposites, the use of diverse biopolymer sources such as polysaccharides, the reinforcement of nanosized materials with biopolymers, and applications of these biopolymers, bionanocomposites, and biohybrid materials will constitute the backbone of this Special Issue