Antifungal Activity of Nontoxic Nanocomposite Based on Silver and Reduced Graphene Oxide against Dermatophytes and Candida spp

Dermatomycoses are typical hair, skin, or nail infections caused mainly by dermatophytes and nondermatophytes: Trichophyton, Microsporum, Epidermophyton, and Candida. In addition to the esthetical impact, pain, and nail deformity, these mycoses can be a source of severe disease. The high cost of treatment, toxicity, and the emergence of resistant infectious agents justifies research into new drugs. This work evaluates the fungicidal activity of nanocomposites (NCs) based on reduced graphene oxide (rGO) loaded with silver (Ag) nanoparticles (rGO/Ag) against clinical isolates of dermatophytes and Candida species. This is an unprecedented study in which, for the first time, hybrid nanocompounds based on Ag/rGO were tested against Epidermophytom, Microsporum, and Trichophyton species (dermatophytes agents). In this paper, we synthesize rGO using different concentrations of Ag by hydrolysis of metal salt AgNO3 and follow the growth of nanocrystals on sheets of rGO provided by the NaBH4. The NCs were analyzed by X-ray diffraction analysis, and the NC morphology, silver distribution on the rGO surface, and crystalline information were investigated by transmission electron microscopy. Antifungal susceptibility assay was performed by the microdilution method based on modified Clinical and Laboratory Standards Institute (CLSI) protocol. Time-kill kinetics was conducted to monitor the effect of the composite to inhibit fungal cells or promote structural changes, avoiding germination. The toxicological evaluation of the NCs was born in an in vivo model based on Galleria mellonella (G. mellonella). Minimum inhibitory concentration (MIC) values of the rGO/Ag NCs ranged from 1.9 to 125 μg/mL. The best inhibitory activity was obtained for rGO/Ag12%, mainly against Candida spp. and Epidermophyton floccosum. In the presence of sorbitol, MIC values of rGO/Ag NCs were higher (ranging from 15.6 to 250 μg/mL), indicating the action mechanism on the cell wall. Both yeast and dermatophytes clinical isolates were inhibited at a minimum of 6 and 24 h, respectively, but after 2 and 12 h, they had initial antifungal interference. All hybrid formulations of rGO/Ag NCs were not toxic for G. mellonella. This study provides insights into an alternative therapeutic strategy for controlling dermatomycoses.

In Vitro and In Vivo Evaluation of Metformin Hydrochloride Hydrogels Developed with Experimental Design in the Treatment of Burns

Burns alter the normal skin barrier and affect various host defense processes that help prevent infections. An ineffective repair process can lead to serious damage, such as the onset of an infection or skin loss, which can then harm the surrounding tissues and ultimately the entire organism. This study aims to prepare in situ gels containing metformin hydrochloride, a compound known for its wound healing properties. To achieve this, in situ gels were prepared using three different gelling agents (Poloxamer 407®, Carbopol 934®, and sodium carboxymethyl cellulose (Na-CMC)) and three different concentrations of metformin hydrochloride (4 mg/g, 6 mg/g, and 8 mg/g), which were optimized through experimental design. Metformin concentration and gelling agent type were independent variables, and the loaded amount and the percentage of metformin released after 150 min were chosen as dependent variables in the optimization process. After determining the optimum values of the dependent variables according to the ANOVA analysis results, in vivo studies were conducted with optimized hydrogel formulations. Two groups, each consisting of seven Wistar rats with a burn model, were treated with metformin-poloxamer 407® gels at doses of 4 mg/g and 8 mg/g for 29 days. The results were then compared to untreated and placebo gel groups. Rats treated with in situ Poloxamer 407® hydrogels containing metformin hydrochloride showed a significant reduction in the size of the burned area after 29 days of treatment. However, for a comprehensive understanding of the wound healing mechanism, further studies such as immuno-histochemical and cell culture studies are needed.

In-vivo evaluations of bone regenerative potential of two novel bioactive glasses

Due to the aging of population, materials able to repair damaged tissues are needed. Among others, bioactive glasses (BGs) have attracted a lot of interest due to their outstanding properties both for hard and soft tissues. Here, for the first time, two new BGs, which gave very promising results in preliminary in vitro-tests, were implanted in animals in order to evaluate their regenerative potential. The new BGs, named BGMS10 and Bio_MS and containing specific therapeutic ions, were produced in granules and implanted in rabbits' femurs for up to 60 days, to test their biocompatibility and osteoconduction. Additionally, granules of 45S5 Bioglass® were employed and used as a standard reference for comparison. The results showed that, after 30 days, the two novel BGs and 45S5 displayed a similar behavior, in terms of bone amount, thickness of new bone trabeculae and affinity index. On the contrary, after 60 days, 45S5 granules were mainly surrounded by wide and scattered bone trabeculae, separated by large amounts of soft tissue, while in BGMS10 and Bio_MS the trabeculae were thin and uniformly distributed around the BG granules. This latter scenario could be considered as more advantageous, since the features of the two novel BG granules allowed for the neo-formation of a uniformly distributed bony trabeculae, predictive of more favorable mechanical behavior, compared to the less uniform coarse trabeculae, separated by large areas of soft tissue in 45S5 granules. Thus, BGMS10 and Bio_MS could be considered suitable products for tissue regeneration in the orthopedic and dental fields.

4.2 million and counting… The animal toll for REACH systemic toxicity studies

The EU's chemicals regulation, REACH, requires that most chemicals in the EU be evaluated for human health and ecosystem risks, with a mandate to minimize use of animal tests for these evaluations. The REACH process has been ongoing since about 2008, but a calculation of the resulting animal use is not publicly available. For this reason, we have undertaken a count of animals used for REACH. With EU legislators set to consider REACH revisions that could expand animal testing, we are releasing results for test categories counted to date: reproductive toxicity tests, developmental toxicity tests, and repeat-ed-dose toxicity tests for human health. The total animal count as of December 2022 for these categories is about 2.9 million. Additional tests involving about 1.3 million animals are currently required by a final proposal authorization or compliance check but not yet completed. The total, 4.2 million, for just these three test categories exceeds the original European Com-mission forecast of 2.6 million for all REACH tests. The difference is primarily because the European Commission estimate excluded offspring, which are most of the animals used for REACH. Other reasons for the difference are extra animals included in tests to ensure sufficient survive to meet the minimum test requirement; dose range-finding tests; extra test animal groups, e.g., for recovery analysis; and a high rejection rate of read-across studies. Given higher than forecast animal use, the upcoming debate on proposed REACH revisions is an opportunity to refocus on reducing animal numbers in keeping with the REACH mandate.

Drug-Loaded Polymeric Micelles Based on Smart Biocompatible Graft Copolymers with Potential Applications for the Treatment of Glaucoma

Glaucoma is the second leading cause of blindness in the world. Despite the fact that many treatments are currently available for eye diseases, the key issue that arises is the administration of drugs for long periods of time and the increased risk of inflammation, but also the high cost of eye surgery. Consequently, numerous daily administrations are required, which reduce patient compliance, and even in these conditions, the treatment of eye disease is too ineffective. Micellar polymers are core–shell nanoparticles formed by the self-assembly of block or graft copolymers in selective solvents. In the present study, polymeric micelles (PMs) were obtained by dialysis from smart biocompatible poly(ε-caprolactone)-poly(N-vinylcaprolactam-co-N-vinylpyrrolidone) [PCL-g-P(NVCL-co-NVP)] graft copolymers. Two copolymers with different molar masses were studied, and a good correlation was noted between the micellar sizes and the total degree of polymerisation (DPn) of the copolymers. The micelles formed by Cop A [PCL120-g-P(NVCL507-co-NVP128)], with the lowest total DPn, have a Z-average value of 39 nm, whereas the micellar sizes for Cop B [PCL120-g-P(NVCL1253-co-NVP139)] are around 47 nm. These PMs were further used for the encapsulation of two drugs with applications for the treatment of eye diseases. After the encapsulation of Dorzolamide, a slight increase in micellar sizes was noted, whereas the encapsulation of Indomethacin led to a decrease in these sizes. Using dynamic light scattering, it was proved that both free and drug-loaded PMs are stable for 30 days of storage at 4 °C. Moreover, in vitro biological tests demonstrated that the obtained PMs are both haemo- and cytocompatible and thus can be used for further in vivo tests. The designed micellar system proved its ability to release the encapsulated drugs in vitro, and the results obtained were validated by in vivo tests carried out on experimental animals, which proved its high effectiveness in reducing intraocular pressure.

Assessment of Physicochemical and In Vivo Biological Properties of Polymeric Nanocapsules Based on Chitosan and Poly(N-vinyl pyrrolidone-alt-itaconic anhydride)

Drug delivery is an important field of nanomedicine, and its aim is to deliver specific active substances to a precise site of action in order to produce a desired pharmacological effect. In the present study nanocapsules were obtained by a process of interfacial condensation between chitosan (dissolved in the aqueous phase) and poly(N-vinyl pyrrolidone-alt-itaconic anhydride), a highly reactive copolymer capable of easily opening the anhydride ring under the action of amine groups of chitosan. The formed amide bonds led to the formation of a hydrogel membrane. The morphology of the obtained nanocapsules, their behavior in aqueous solution of physiological pH, and their ability to encapsulate and release a model drug can be modulated by the parameters of the synthesis process, such as the molar ratio between functional groups of polymers and the ratio of the phases in which the polymers are solubilized. Although a priori both polymers are biocompatible, this paper reports the results of a very detailed in vivo study conducted on experimental animals which have received the obtained nanocapsules by three administration routes—intraperitoneal, subcutaneous, and oral. The organs taken from the animals’ kidney, liver, spleen, and lung and analyzed histologically demonstrated the ability of nanocapsules to stimulate the monocytic macrophage system without producing inflammatory changes. Moreover, their in vivo behavior has been shown to depend not only on the route of administration but also on the interaction with the cells of the organs with which they come into contact. The results clearly argue the biocompatibility of nanocapsules and hence the possibility of their safe use in biomedical applications.

Isolation of Klebsiella pneumoniae Phage vB_KpnS_MK54 and Pathological Assessment of Endolysin in the Treatment of Pneumonia Mice Model

With the improper use of antibiotics, an increasing number of multidrug-resistant bacteria have been reported worldwide, posing challenges for disease treatment. Klebsiella pneumoniae is an important zoonotic pathogen that colonises the respiratory tract. Endolysin therapy has emerged with the development of phages. In this study, a lytic phage vB_KpnS_MK54 was isolated from the drinking water of a forest musk deer (FMD) farm in Sichuan Province. It was the first reported phage obtained from FMD. The primary biological characteristics were determined, and whole-genome sequencing analysis was performed. The phage which belongs to the family Siphoviridae is highly specific for lytic host bacteria and is moderately adaptable to different environments. Whole-genome sequencing results showed that the phage genome size was 46,218 bp. There were 80 coding DNA sequences (CDSs) in total, 32 of which had known functions. The last CDS is the phage endolysin LysG24. A new peptide-modified endolysin (LysCA) was constituted by connecting the cecropin A peptide residues with LysG24 to investigate the antibacterial activities of both LysG24 and LysCA. The results showed that the lytic profile of LysG24 and LysCA was wider than that of phage MK54. For in vitro tests, both endolysins destroyed 99% of the host bacteria within 6 h. The lysing ability and environmental adaptability of LysCA were significantly stronger than those of LysG24. For in vivo tests, LysG24 and LysCA exhibited therapeutic effects in a mouse model of pneumonia wherewith the mice were infected with K. pneumoniae (LPKP), wherein both LysG24 and LysCA can effectively reduce the pulmonary inflammatory response. The LPKP bacterial load in the treatment group was significantly lower than that in the bacterial group, among which LysCA displayed a more obvious therapeutic effect. Furthermore, the safety test showed that the endolysins had no toxic effects on mice. In general, both LysG24 and LysCA showed excellent antibacterial activity in vivo and in vitro, with high safety and strong adaptability to the environment, manifesting their latent potential as new antimicrobial agents.

Bioactive Glasses in Periodontal Regeneration: Existing Strategies and Future Prospects-A Literature Review

The present review deals with bioactive glasses (BGs), a class of biomaterials renowned for their osteoinductive and osteoconductive capabilities, and thus widely used in tissue engineering, i.e., for the repair and replacement of damaged or missing bone. In particular, the paper deals with applications in periodontal regeneration, with a special focus on in vitro, in vivo and clinical studies. The study reviewed eligible publications, identified on the basis of inclusion/exclusion criteria, over a ranged time of fifteen years (from 1 January 2006 to 31 March 2021). While there are many papers dealing with in vitro tests, only a few have reported in vivo (in animal) research, or even clinical trials. Regardless, BGs seem to be an adequate choice as grafts in periodontal regeneration.

Studies on Activities and Chemical Characterization of Medicinal Plants in Search for New Antimalarials: A Ten Year Review on Ethnopharmacology

Malaria is an endemic disease that affected 229 million people and caused 409 thousand deaths, in 2019. Disease control is based on early diagnosis and specific treatment with antimalarial drugs since no effective vaccines are commercially available to prevent the disease. Drug chemotherapy has a strong historical link to the use of traditional plant infusions and other natural products in various cultures. The research based on such knowledge has yielded two drugs in medicine: the alkaloid quinine from Cinchona species, native in the Amazon highland rain forest in South America, and artemisinin from Artemisia annua, a species from the millenary Chinese medicine. The artemisinin-based combination therapies (ACTs), proven to be highly effective against malaria parasites, and considered as “the last bullet to fight drug-resistant malaria parasites,” have limited use now due to the emergence of multidrug resistance. In addition, the limited number of therapeutic options makes urgent the development of new antimalarial drugs. This review focuses on the antimalarial activities of 90 plant species obtained from a search using Pubmed database with keywords “antimalarials,” “plants” and “natural products.” We selected only papers published in the last 10 years (2011–2020), with a further analysis of those which were tested experimentally in malaria infected mice. Most plant species studied were from the African continent, followed by Asia and South America; their antimalarial activities were evaluated against asexual blood parasites, and only one species was evaluated for transmission blocking activity. Only a few compounds isolated from these plants were active and had their mechanisms of action delineated, thereby limiting the contribution of these medicinal plants as sources of novel antimalarial pharmacophores, which are highly necessary for the development of effective drugs. Nevertheless, the search for bioactive compounds remains as a promising strategy for the development of new antimalarials and the validation of traditional treatments against malaria. One species native in South America, Ampelozyzyphus amazonicus, and is largely used against human malaria in Brazil has a prophylactic effect, interfering with the viability of sporozoites in in vitro and in vivo experiments.

Production and Characterization of Chitooligosaccharides: Evaluation of Acute Toxicity, Healing, and Anti-Inflammatory Actions

The search for promising biomolecules such as chitooligosaccharides (COS) has increased due to the need for healing products that act efficiently, avoiding complications resulting from exacerbated inflammation. Therefore, this study aimed to produce COS in two stages of hydrolysis using chitosanases derived from Bacillus toyonensis. Additionally, this study aimed to structurally characterize the COS via mass spectrometry, to analyze their biocompatibility in acute toxicity models in vivo, to evaluate their healing action in a cell migration model in vitro, to analyze the anti-inflammatory activity in in vivo models of xylol-induced ear edema and zymosan-induced air pouch, and to assess the wound repair action in vivo. The structural characterization process pointed out the presence of hexamers. The in vitro and in vivo biocompatibility of COS was reaffirmed. The COS stimulated the fibroblast migration. In the in vivo inflammatory assays, COS showed an antiedematogenic response and significant reductions in leukocyte migration, cytokine release, and protein exudate. The COS healing effect in vivo was confirmed by the significant wound reduction after seven days of the experiment. These results indicated that the presence of hexamers influences the COS biological properties, which have potential uses in the pharmaceutical field due to their healing and anti-inflammatory action.

Skin tests for the exploration of hypersensitivity reactions associated with iodinated contrast media

BACKGROUND

Iodinated contrast media (ICM) are responsible for multiple side effects, especially hypersensitivity reactions. These reactions can either be authentic allergies, or non-allergic hypersensitivity reactions. Skin tests (prick and intradermal tests) are simple to perform and can be of great help, especially if the ICM need to be re-used. The aim of the study was to assess the characteristics of the patients in whom skin tests were performed, and the results of these tests.

METHODS

This is a retrospective study from June 2014 to June 2019. All included patients had at least one episode of hypersensitivity reaction to ICM and underwent skin tests.

RESULTS

We included 35 patients aged 18 to 85 years. The iopromide was the most implicated ICM. The reactions were mainly cutaneous (n=30) and immediate (n=27). The skin tests were negative, except for two patients. The reuse of ICM occured in 11 patients: 9 with an ICM other than the one suspected and two patients with the same ICM. Among these patients, 5 did not have any premedication. Two of them had a second hypersensitivity reaction, the first with another ICM and the second with the same ICM.

CONCLUSION

One of the main pillars of allergic exploration is ICM skin testing, not only to prevent recurrence, but also to allow patients to benefit from ICM reuse, which are sometimes essential.

Continuing animal tests on cosmetic ingredients for REACH in the EU

EU cosmetic ingredients are governed by two regulations that conflict. Regulation EC 1223/2009, the Cosmetic Regulation, bans in vivo (animal) testing for cosmetic product safety assessments, including both final products and ingredients. At the same time, the Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) regulation can impose in vivo testing of those same ingredients under its chemical testing requirements. Here, we examined REACH dossiers for chemicals for which the only reported use is cosmetics to determine the extent of new in vivo testing caused by REACH. We found the REACH database has 3,206 chemical dossiers with cosmetics as a reported use. Of these, 419 report cosmetics as the only use, and 63 of these have in vivo tests completed after the Cosmetic Regulation ban on in vivo testing. Registrants largely used alternative, non-animal methods to evaluate ingredients for REACH, but some still conducted new in vivo tests to comply with REACH requirements for toxicity data and worker safety assessments. In some cases, ECHA, the agency that evaluates REACH dossiers, rejected registrants’ alternative methods as insufficient and required new in vivo tests. As ECHA continues to evaluate dossiers, more requests for in vivo tests are likely. REACH tests on cosmetic ingredients appear only as “industrial chemicals legislation” tests in EU reports. Given the importance to consumers and the cosmetic industry of having cosmetics free of animal testing, the public should be made aware of REACH testing until the conflict between the regulations is resolved.

Water as a Blood Model for Determination of CO2 Removal Performance of Membrane Oxygenators

CO₂ removal via membrane oxygenators has become an important and reliable clinical technique. Nevertheless, oxygenators must be further optimized to increase CO₂ removal performance and to reduce severe side effects. Here, in vitro tests with water can significantly reduce costs and effort during development. However, they must be able to reasonably represent the CO₂ removal performance observed with blood. In this study, the deviation between the CO₂ removal rate determined in vivo with porcine blood from that determined in vitro with water is quantified. The magnitude of this deviation (approx. 10%) is consistent with results reported in the literature. To better understand the remaining difference in CO₂ removal rate and in order to assess the application limits of in vitro water tests, CFD simulations were conducted. They allow to quantify and investigate the influences of the differing fluid properties of blood and water on the CO₂ removal rate. The CFD results indicate that the main CO₂ transport resistance, the diffusional boundary layer, behaves generally differently in blood and water. Hence, studies of the CO₂ boundary layer should be preferably conducted with blood. In contrast, water tests can be considered suitable for reliable determination of the total CO₂ removal performance of oxygenators.

Titanium-Based Alloy Surface Modification with TiO2 and Poly(sodium 4-styrenesulfonate) Multilayers for Dental Implants

Implant placement is an important repair method in dentistry and orthopedics. Increasing efforts have focused on optimizing the biocompatibility and osseointegration properties of titanium (Ti) and Ti-based alloys. In this work, Ti-based alloys were modified by the layer-by-layer (LbL) technique, which is a simple and versatile method for surface modification. The morphology and chemical structure of LbL films of poly(sodium 4-styrenesulfonate) (PSS) and Ti dioxide (TiO₂) nanoparticles were first characterized employing ultraviolet-visible and Fourier-transform infrared spectroscopies as well as atomic force microscopy for further application in Ti-based alloy implants. The changes provoked by the LbL PSS/TiO₂ film on the Ti-based alloy surfaces were then investigated by scanning electron microscopy and micro-Raman techniques. Finally, in vivo tests (immunolabeling and biomechanical analysis) performed with screw implants in rats suggested that PSS/TiO₂ multilayers promote changes in both topography and chemical surface properties of the screw, providing beneficial effects for osteoblast activity. This simple and relatively low-cost growth process can open up possibilities to improve dental implants and, probably, bone implants in general.

Tissue Engineering for the Insertions of Tendons and Ligaments: An Overview of Electrospun Biomaterials and Structures

The musculoskeletal system is composed by hard and soft tissue. These tissues are characterized by a wide range of mechanical properties that cause a progressive transition from one to the other. These material gradients are mandatory to reduce stress concentrations at the junction site. Nature has answered to this topic developing optimized interfaces, which enable a physiological transmission of load in a wide area over the junction. The interfaces connecting tendons and ligaments to bones are called entheses, while the ones between tendons and muscles are named myotendinous junctions. Several injuries can affect muscles, bones, tendons, or ligaments, and they often occur at the junction sites. For this reason, the main aim of the innovative field of the interfacial tissue engineering is to produce scaffolds with biomaterial gradients and mechanical properties to guide the cell growth and differentiation. Among the several strategies explored to mimic these tissues, the electrospinning technique is one of the most promising, allowing to generate polymeric nanofibers similar to the musculoskeletal extracellular matrix. Thanks to its extreme versatility, electrospinning has allowed the production of sophisticated scaffolds suitable for the regeneration of both the entheses and the myotendinous junctions. The aim of this review is to analyze the most relevant studies that applied electrospinning to produce scaffolds for the regeneration of the enthesis and the myotendinous junction, giving a comprehensive overview on the progress made in the field, in particular focusing on the electrospinning strategies to produce these scaffolds and their mechanical, in vitro, and in vivo outcomes.

Surface-Modified Poly(l-lactide-co-glycolide) Scaffolds for the Treatment of Osteochondral Critical Size Defects-In Vivo Studies on Rabbits

Poly(l-lactide-co-glycolide) (PLGA) porous scaffolds were modified with collagen type I (PLGA/coll) or hydroxyapatite (PLGA/HAp) and implanted in rabbits osteochondral defects to check their biocompatibility and bone tissue regeneration potential. The scaffolds were fabricated using solvent casting/particulate leaching method. Their total porosity was 85% and the pore size was in the range of 250-320 µm. The physico-chemical properties of the scaffolds were evaluated using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), sessile drop, and compression tests. Three types of the scaffolds (unmodified PLGA, PLGA/coll, and PLGA/HAp) were implanted into the defects created in New Zealand rabbit femoral trochlears; empty defect acted as control. Samples were extracted after 1, 4, 12, and 26 weeks from the implantation, evaluated using micro-computed tomography (µCT), and stained by Masson-Goldner and hematoxylin-eosin. The results showed that the proposed method is suitable for fabrication of highly porous PLGA scaffolds. Effective deposition of both coll and HAp was confirmed on all surfaces of the pores through the entire scaffold volume. In the in vivo model, PLGA and PLGA/HAp scaffolds enhanced tissue ingrowth as shown by histological and morphometric analyses. Bone formation was the highest for PLGA/HAp scaffolds as evidenced by µCT. Neo-tissue formation in the defect site was well correlated with degradation kinetics of the scaffold material. Interestingly, around PLGA/coll extensive inflammation and inhibited tissue healing were detected, presumably due to immunological response of the host towards collagen of bovine origin. To summarize, PLGA scaffolds modified with HAp are the most promising materials for bone tissue regeneration.

Bacterial Cellulose-Modified Polyhydroxyalkanoates Scaffolds Promotes Bone Formation in Critical Size Calvarial Defects in Mice

Bone regeneration is a claim challenge in addressing bone defects with large tissue deficits, that involves bone grafts to support the activity. In vitro biocompatibility of the bacterial cellulose-modified polyhydroxyalkanoates (PHB/BC) scaffolds and its osteogenic potential in critical-size mouse calvaria defects had been investigated. Bone promotion and mineralization were analyzed by biochemistry, histology/histomorphometry, X-ray analysis and immunofluorescence for highlighting osteogenesis markers. In summary, our results showed that PHB/BC scaffolds are able to support 3T3-L1 preadipocytes proliferation and had a positive effect on in vivo osteoblast differentiation, consequently inducing new bone formation after 20 weeks post-implantation. Thus, the newly developed PHB/BC scaffolds could turn out to be suitable biomaterials for the bone tissue engineering purpose.

The effects of bone implants' coating mechanical properties on osseointegration: In vivo, in vitro, and histological investigations

The main goal of this work was to investigate the effects of implants coatings' mechanical properties and morphology on the osseointegration. In order to produce different mechanical properties of coatings, two thermal spray techniques, high velocity oxy-fuel (HVOF) and air plasma spray (APS) were employed. Titanium pins were coated and implanted into the distal femurs and proximal tibias of fifteen New Zealand white rabbits, equally distributed in three study groups, and a total of 20 pins implanted in each group. Eight weeks after insertion, the rabbits were euthanized and the femur samples were taken out for biomechanical tests and tibia samples for histological evaluations of osseointegration. Scanning electron microscopy results showed enhanced density and a better morphology of HVOF coatings, compared to APS samples, and X-ray diffraction characterized an enhanced crystallinity of HVOF coatings. Nanoindentation tests revealed greater hardness and elastic modulus of HVOF coatings, whereas greater tensile residual stress and more pronounced creep was observed for APS coatings. Neither in biomechanical tests, nor in the histological analyses, a significant difference was observed between HVOF and APS coated samples (p > 0.05, and p > 0.05, respectively). The lack of significant difference between the HVOF and APS coated implants' osseointegration rejected our hypothesis to have a more enhanced osseointegration due to a better morphology, as well as stronger mechanical properties of HA coatings. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2679-2691, 2018.

Current trends and perspectives of bioactive peptides

The remarkable growth of therapeutic peptide development in the past decade has led to a large number of market approvals and the market value is expected to hit $25 billion by 2018. This significant market increase is driven by the increasing incidences of metabolic and cardiovascular diseases and technological advancements in peptide synthesis. For this reason, the search for bioactive peptides has also increased exponentially. Many bioactive peptides from food and nonfood sources have shown positive health effects yet, obstacles such as the need to implement efficient and cost-effective strategies for industrial scale production, good manufacturing practices as well as well-designed clinical trials to provide robust evidence for supporting health claims continue to exist. Several other factors such as the possibility of allergenicity, toxicity and the stability of biological functions of the peptides during gastrointestinal digestion would need to be addressed.