Cellulose is one of the most important natural polymers on earth and its various nanoscale forms provide new opportunities for groundbreaking discoveries in materials science. The current state of ...nanocellulose research and development, in terms of production and processing (including international market launch), structural details, properties, and innovative applications in life sciences and engineering technology is featured.
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Nanocelluloses are natural materials with at least one dimension in the nano-scale. They combine important cellulose properties with the features of nanomaterials and open new horizons for materials science and its applications. The field of nanocellulose materials is subdivided into three domains: biotechnologically produced bacterial nanocellulose hydrogels, mechanically delaminated cellulose nanofibers, and hydrolytically extracted cellulose nanocrystals. This review article describes today’s state regarding the production, structural details, physicochemical properties, and innovative applications of these nanocelluloses. Promising technical applications including gels/foams, thickeners/stabilizers as well as reinforcing agents have been proposed and research from last five years indicates new potential for groundbreaking innovations in the areas of cosmetic products, wound dressings, drug carriers, medical implants, tissue engineering, food and composites. The current state of worldwide commercialization and the challenge of reducing nanocellulose production costs are also discussed.
Cellulose fibrils with widths in the nanometer range are nature‐based materials with unique and potentially useful features. Most importantly, these novel nanocelluloses open up the strongly ...expanding fields of sustainable materials and nanocomposites, as well as medical and life‐science devices, to the natural polymer cellulose. The nanodimensions of the structural elements result in a high surface area and hence the powerful interaction of these celluloses with surrounding species, such as water, organic and polymeric compounds, nanoparticles, and living cells. This Review assembles the current knowledge on the isolation of microfibrillated cellulose from wood and its application in nanocomposites; the preparation of nanocrystalline cellulose and its use as a reinforcing agent; and the biofabrication of bacterial nanocellulose, as well as its evaluation as a biomaterial for medical implants.
Cellulose goes nano: Renewed research effort on cellulose has led to nanoscale materials derived from this abundant, renewable, and potentially carbon‐neutral source. Microfibrillated cellulose, nanocrystalline cellulose (see polarized microscopy image), and bacterial nanocellulose provide unique product opportunities: gels and foams, structured films of cellulose, and medical implants, respectively.
There is an increasing need for small diameter vascular grafts with superior host hemo- and cytocompatibilities, such as low activation of platelets and leukocytes. Therefore, we aimed to investigate ...whether the preparation of bacterial nanocellulose grafts with different inner surfaces has an impact on in vitro host cytocompatibility. We have synthesized five different grafts in a bioreactor, namely open interface surface (OIS), inverted (INV), partially air dried (PAD), surface formed in air contact (SAC) and standard (STD) that were characterized by a different surface roughness. The grafts (length 55 mm, inner diameter 5 mm) were attached to heparinized polyvinyl chloride tubes, loaded with human blood and rotated at 37°C for 4 hours. Then, blood was analyzed for frequencies of cellular fractions, oxidative products, soluble complement and thrombin factors. The results were compared to clinically approved grafts made of polyethylene terephthalate and expanded polytetrafluoroethylene. Additionally, blood platelets were labelled with .sup.111 Indium-oxine to visualize the distribution of adherent platelets in the loop by scintigraphy. SAC nanocellulose grafts with the lowest surface roughness exhibited superior performance with <10% leukocyte and 65% leukocyte and >90% thrombocyte loss. Of note, SAC nanocellulose grafts showed lowest radioactivity with scintigraphy analyses, indicating reduced platelet adhesion. Although the levels of reactive oxygen species and cell free DNA did not differ significantly, the levels of thrombin-antithrombin complexes were lowest in SAC grafts. However, all nanocellulose grafts exhibited enhanced complement activation. The systematic variation of the inner surfaces of BNC vascular grafts significantly improves biocompatibility. Especially, SAC grafts exhibited the lowest loss of platelets as well as leukocytes and additionally significantly diminished activation of the coagulation system. Further animal studies are needed to study in vivo biocompatibilities.
Large populations of unowned cats constitute an animal welfare, ecological, societal and public health issue worldwide. Their relocation and homing are currently carried out in many parts of the ...world with the intention of relieving suffering and social problems, while contributing to ethical and humane population control in these cat populations. An understanding of an individual cat's lifestyle and disease status by veterinary team professionals and those working with cat charities can help to prevent severe cat stress and the spread of feline pathogens, especially vector-borne pathogens, which can be overlooked in cats. In this article, we discuss the issue of relocation and homing of unowned cats from a global perspective. We also review zoonotic and non-zoonotic infectious agents of cats and give a list of practical recommendations for veterinary team professionals dealing with homing cats. Finally, we present a consensus statement consolidated at the 15th Symposium of the Companion Vector-Borne Diseases (CVBD) World Forum in 2020, ultimately to help veterinary team professionals understand the problem and the role they have in helping to prevent and manage vector-borne and other pathogens in relocated cats.
The biomaterial bacterial cellulose (BC) represents an innovative approach for overcoming reconstructive problems associated with extended vascular diseases by providing small caliber vascular grafts ...(diameter 1.0-3.7, length 5.0-10.0, and wall-thickness 0.7 mm). In a first microsurgical study, the BC implants were attached in an artificial defect of the carotid artery of rats for 1 year. These long term results show the incorporation of the BC under formation of neointima and ingrowth of active fibroblasts. In a second study, the grafts were used to replace the carotid arteries of pigs. After 3 months, these grafts were removed and analyzed both macro- and microscopically. Seven grafts (87.5%) were patent whereas one graft was found occluded. These data indicate that the innovative BC engineering technique results in the production of stable vascular conduits and confirm a highly attractive approach to in vivo tissue engineered blood vessels as part of programs in cardiovascular surgery.
Companion vector-borne diseases (CVBDs) are an important threat for pet life, but may also have an impact on human health, due to their often zoonotic character. The importance and awareness of CVBDs ...continuously increased during the last years. However, information on their occurrence is often limited in several parts of the world, which are often especially affected. Latin America (LATAM), a region with large biodiversity, is one of these regions, where information on CVBDs for pet owners, veterinarians, medical doctors and health workers is often obsolete, limited or non-existent. In the present review, a comprehensive literature search for CVBDs in companion animals (dogs and cats) was performed for several countries in Central America (Belize, Caribbean Islands, Costa Rica, Cuba, Dominican Republic, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, Panama, Puerto Rico) as well as in South America (Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, French Guiana, Guyana (British Guyana), Paraguay, Peru, Suriname, Uruguay, Venezuela) regarding the occurrence of the following parasitic and bacterial diseases: babesiosis, heartworm disease, subcutaneous dirofilariosis, hepatozoonosis, leishmaniosis, trypanosomosis, anaplasmosis, bartonellosis, borreliosis, ehrlichiosis, mycoplasmosis and rickettsiosis. An overview on the specific diseases, followed by a short summary on their occurrence per country is given. Additionally, a tabular listing on positive or non-reported occurrence is presented. None of the countries is completely free from CVBDs. The data presented in the review confirm a wide distribution of the CVBDs in focus in LATAM. This wide occurrence and the fact that most of the CVBDs can have a quite severe clinical outcome and their diagnostic as well as therapeutic options in the region are often difficult to access and to afford, demands a strong call for the prevention of pathogen transmission by the use of ectoparasiticidal and anti-feeding products as well as by performing behavioural changes.
Biocompatible bacterial nanocellulose (BNC) shows high potential as wound dressing and
dura mater
replacement, and even for the development of blood vessel or cartilage implants. Thus, the ...regenerative capacity of BNC implants was analyzed using a standardized bovine cartilage punch model. Cartilage rings with an outer diameter of 6 mm and an inner defect diameter of 2 mm were derived from the trochlear groove (femur-patellar articulation site). BNC implants were cultured inside the cartilage rings for up to 12 weeks. Cartilage-BNC-constructs were then evaluated by histology (hematoxylin/eosin; safranin O), immunohistology (aggrecan, collagens 1 and 2), and for protein content, mRNA expression, and push-out force of the implants. Cartilage-BNC-constructs displayed vital chondrocytes (≥ 90% until week 9; > 80% until 12 weeks), preserved matrix integrity during culture, limited loss of matrix-bound proteoglycan from ‘host’ cartilage or cartilage-BNC-interface, and constant release of proteoglycans into the culture supernatant. In addition, the content of the matrix protein collagen 2 in cartilage and cartilage-BNC-interface was approximately constant over time (with very limited quantities of collagen 1). Interestingly, BNC implants showed: (1) cell colonization of the implant; (2) progressively increasing mRNA levels for the proteoglycan aggrecan and collagen 2 (max. fivefold); and (3) significantly increasing push-out forces during culture (max. 1.6-fold). Retained tissue integrity and progressively increasing chondrogenic differentiation in implant and cartilage-implant-interface suggest beginning cartilage regeneration in the BNC in the present model and indicate a high potential of BNC as a cartilage replacement material. Thus, the present model appears suitable to predict the in vivo performance of cartilage replacement materials (e.g., BNC) for tissue engineering.
Graphical abstract
Using a “never‐dried” procedure (according to Figure 4) shaped bacterial nanocellulose (BC, 1% cellulose, 99% water) has been modified by the formation of BC‐polymer composites. For this purpose, ...acrylate and methacrylate monomers and methacrylate crosslinkers were photopolymerized inside an ethanol‐swollen nanofiber network. Using the ethanol as solvent and as confirmed by model reactions the synthetic polymer (SP) part of the composites is constructed of crosslinked polymers (number of repeating units in the range of 500). As part of ongoing work on the development of (bio)materials from the innovative pool of BC composites these investigations are recently directed towards the creation of collagen‐like materials. Thus, for these purposes, mainly water absorption capacity, strength, and elasticity have to be controlled, whilst still retaining essential features of BC like shape, nanofiber network, pore system, and proved biocompatibility. Using acrylic acid, 2‐ethylhexyl acrylate, 2‐hydroxyethyl methacrylate, N‐vinyl pyrrolidone as acrylate monomers and triethylene glycol dimethacrylate and 1,4‐butandiol dimethacrylate as crosslinkers of different concentrations either a filling of the pores or a coating of the fibers in the BC nanocomposites could be achieved. The small cellulose content of the composites significantly increases the water absorption value and the strength of the material as well as the ability of re‐swelling in the case of fiber coated composites. Sample 12 is an optimized BC‐SP composite regarding important properties of hyaline cartilage like Young's modulus in the range of 5–20 MPa using the well‐known Simplex‐method.
•A review on progress in product design of Biotech nanocellulose (BNC).•Template-based production of multilayered tubes, membranes, composites and coatings.•Process-controlled design of shape, ...surfaces and nanonetwork architecture.•Groundbreaking application fields: medical implants and drug delivery systems.•Potential of multilayered BNC for techniques such as electronics.
Biotech nanocellulose (bacterial nanocellulose, BNC) is a high potential natural polymer. Moreover, it is the only cellulose type that can be produced biotechnologically using microorganisms resulting in hydrogels with high purity, high mechanical strength and an interconnecting micropore system. Recently, the subject of intensive research is to influence this biosynthesis to create function-determining properties. This review reports on the progress in product design and today’s state of technical and medical applications. A novel, dynamic, template-based technology, called Mobile Matrix Reservoir Technology (MMR Tech), is highlighted. Thereby, shape, dimensions, surface properties, and nanonetwork structures can be designed in a process-controlled manner. The formed multilayer materials open up new applications in medicine and technology. Especially medical materials for cardiovascular and visceral surgery, and drug delivery systems are developed. The effective production of layer-structured composites and coatings are important for potential applications in the electronics, paper, food and packaging technologies.
Angiostrongylus vasorum, Crenosoma vulpis and Eucoleus aerophilus are a source of increasing concern, potentially causing significant pulmonary and severe cardiac/systemic diseases in domestic dogs ...and wild canids, especially red foxes (Vulpes vulpes). To investigate the prevalence and geographical distribution of these parasites in central Germany, a total of 569 foxes were examined by dissection.
Pluck (heart and lung) and faecal samples of red foxes were collected from three regions of Germany. Lungs, hearts and adjacent vessels were processed for adult nematode detection. Parasitological diagnoses of faecal samples were performed by SAF technique, Giardia- and Cryptosporidium-Coproantigen-ELISAs and by a duplex copro-PCR for the detection of A. vasorum and C. vulpis DNA.
Foxes originated from three Federal States of central Germany: Thuringia (n = 359); Rhineland-Palatinate (n = 121) and Hesse (n = 89). High prevalences for all three nematodes were detected, with E. aerophilus (69.4%; 395/569), followed by C. vulpis (32.3%; 184/569) and A. vasorum (14.1%; 80/569). In case of A. vasorum, prevalences varied significantly between Federal States, with the highest prevalence of 27.3% in Rhineland-Palatinate, followed by 19.1% and 8.4% in Hesse and Thuringia, respectively. The presence of A. vasorum in fox populations showed a rather patchy distribution, increasing from north-eastern to south-western regions. Analyses on C. vulpis revealed prevalences of 35.1%, 30.3% and 25.6% (Thuringia, Hesse and Rhineland-Palatinate, respectively). The most prevalent lungworm nematode was E. aerophilus, with a prevalence of 75.2%, 71.9% and 66.9% (Rhineland-Palatinate, Hesse and Thuringia, respectively) and an almost area-wide equal distribution. Significant differences for single parasite prevalences within geographical regions of the Federal States could be detected whilst no correlation between age or gender and parasite occurrence was estimated. Weak seasonality for the winter months for A. vasorum, stronger correlation to spring and late summer for C. vulpis and no correlation to any season for E. aerophilus were detected. The method of dissection revealed a significantly higher sensitivity for C. vulpis when compared with the results of the duplex copro-PCR.
A sylvatic cycle was confirmed for all three lungworm nematodes in the examined area. The prevalences for all three lungworm nematodes are some of the highest recorded so far in German foxes. The data suggest that A. vasorum might be spreading from south-western to north-eastern parts of Germany.
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