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Abstract: The increasing interest in strontium incorporation into biomaterials for hard tissue repair is justified by the growing evidence of its beneficial effect on bone. We successfully synthesized hydroxyapatite (HA) thin films with different extents of strontium substitution for calcium (0, 1, 3 or 7at.%) by pulsed-laser deposition. The coatings displayed a granular surface and a good degree of crystallinity, which slightly diminished as strontium content increased. Osteoblast-like MG63 cells and human osteoclasts were cultured on the thin films up to 21 days. MG63 cells grown on the strontium-doped HA coatings displayed normal morphology, good proliferation and increased values of the differentiation parameters, whereas the number of osteoclasts was negatively influenced by the presence of strontium. The positive effect of the ion on bone cells was particularly evident in the case of coatings deposited from HA at relatively high strontium contents (3–7%), where significantly increased values of alkaline phosphatase activity, osteocalcin, type I collagen and osteoprotegerin/TNF-related activation-induced cytokine receptor ratio, and considerably reduced values of osteoclast proliferation, were observed. [Copyright &y& Elsevier]

Critical bone defect repair remains a major medical challenge. Developing biocompatible materials with bone-healing ability is a key field of research, and calcium-deficient apatites (CDA) are appealing bioactive candidates. We previously described a method to cover activated carbon cloths (ACC) with CDA or strontium-doped CDA coatings to generate bone patches. Our previous study in rats revealed that apposition of ACC or ACC/CDA patches on cortical bone defects accelerated bone repair in the short term. This study aimed to analyze in the medium term the reconstruction of cortical bone in the presence of ACC/CDA or ACC/10Sr-CDA patches corresponding to 6 at.% of strontium substitution. It also aimed to examine the behavior of these cloths in the medium and long term, in situ and at distance. Our results at day 26 confirm the particular efficacy of strontium-doped patches on bone reconstruction, leading to new thick bone with high bone quality as quantified by Raman microspectroscopy. At 6 months the biocompatibility and complete osteointegration of these carbon cloths and the absence of micrometric carbon debris, either out of the implantation site or within peripheral organs, was confirmed. These results demonstrate that these composite carbon patches are promising biomaterials to accelerate bone reconstruction. [ABSTRACT FROM AUTHOR]

In this study, matrix-assisted pulsed laser evaporation (MAPLE) was used to deposit graphene-like materials (GL), a new class of biocompatible graphene-related materials (GRMs) obtained from a controlled top-down demolition of a carbon black, on silicone slices to test their potential use as functional coating on invasive medical devices as indwelling urinary catheters. Results indicate that the relevant chemical-physical features of the deposit (controlled by FTIR and AFM) were maintained after MAPLE deposition. After deposition, GL films underwent a biological survey toward target cellular lines (murine fibroblast NIH3T3, human keratinocytes HaCAT and the human cervical adenocarcinoma epithelial-like HeLa). Results indicate that the GL films did not lead to any perturbations in the different biological parameters evaluated. The presented results and the possibility to further functionalize the GL or combine them with other functional materials in a hybrid fashion to assure a tighter adhesion onto the substrate for use in harsh conditions open the door to practical applications of these new-concept medical devices (drug delivery, next generation flexible devices, multifunctional coatings) paving the way to the prevention of nosocomial infections driven by catheterization through antibiotics-free approaches. [ABSTRACT FROM AUTHOR]

The biofilm community of microorganisms has been identified as the dominant mode of microbial growth in nature and a common characteristic of different microorganisms such as Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis. The biofilm structure helps in the protection from environmental threats including host immune system and antimicrobial agents. Thus, the biofilm community has led to a higher prevalence of multidrug-resistant (MDR) strains in recent years. In this regard, the use of a new class of antibiotics, natural compounds, and anti-biofilm enzymes has been considered for the destruction of the microbial biofilm. However, different drawbacks such as low penetration, high susceptibility to degradation, instability, and poor solubility in aqueous solutions limit the use of anti-biofilm agents (ABAs) in a clinical setting. As such, recent studies have been using poly lactic- co -glycolic acid (PLGA)-based nanoplatforms (PLGA NPFs) for delivery of ABAs that have reported promising results. These particles, due to proper drug loading and release kinetics, could suppress microbial attachment, colonization, and biofilm formation for a long time. Additionally, PLGA NPFs, because of the high drug-loading efficiencies, hydrophilic surface, negative charge, and electrostatic interaction, lead to effective penetration of antibiotics to the deeper layer of the biofilm, thereby eliminating the microbial biofilm. Thus, PLGA NPFs could be considered as a potential candidate for coating catheters and other medical material surfaces for inhibition and destruction of the microbial biofilm. However, the exact interaction of PLGA NPFs and the microbial biofilm should be evaluated in animal studies. Additionally, a future goal will be to develop PLGA formulations as systems that can be used for the treatment of the MDR microbial biofilm, since the exact interactions of PLGA NPFs and these biofilm structures are not elucidated. In the present review article, we have discussed various aspects of PLGA usage for inhibition and destruction of the microbial biofilm along with different methods and procedures that have been used for improving PLGA NPF efficacy against the microbial biofilm. [ABSTRACT FROM AUTHOR]

Recently, the advantages of biopolymers over conventional plastic polymers are unprecedented, provided that they are used in situations in which they raise the functionality and generate extra benefits for human life. Therefore, biopolymers have received much attention because they play an important place in day-to-day life for their specific tunable characteristics, making them attractive in a wide range of applications. Biopolymers can produce materials with tunable properties such as biodegradability, biocompatibility, renewability, inexpensiveness, availability, which are critically important for designing materials for use in biomedical applications. In addition to these properties, smart biopolymers could be prepared by changing the polymer components, which would create more target oriented applications. Therefore, this review interprets how biopolymers and their various forms can be potentially used in biomedical applications, including drug delivery, infections, tissue engineering, wound healings, and other as wells. Special emphasis will be provided on the applications of biopolymers in the field of drug delivery, tissue engineering, infections, and wound healing, which indicate the advancement and employment of the various biopolymers in recent biomedical applications. [ABSTRACT FROM AUTHOR]

Cell‐seeded microcarriers (MCs) are currently one of the most promising topics in biotechnology. These systems are supportive structures for cell growth and expansion that allow efficient nutrient and gas transfer between the media and the attached cells. Silk proteins have been increasingly used for this purpose in the past few years due to their biocompatibility, biodegradability and non‐toxicity. To date, several silk fibroin spherical MCs in combination with alginate, gelatin and calcium phosphates have been reported with very interesting outcomes. In addition, other silk‐based three‐dimensional structures such as microparticles with chitosan and collagen, as well as organoids, have been increasingly studied. In this study, the physicochemical and biological properties of these biomaterials, as well as the recent methodologies for their processing and for cell culture, are discussed. The potential biomedical applications are also addressed. In addition, an analysis of the future perspectives is presented, where the potential of innovative silk‐based MCs processing technologies is highlighted. [ABSTRACT FROM AUTHOR]

In this study, hydroxyapatite-alendronate composites were synthesized from calcium nitrate, diammonium hydrogen phosphate and alendronate by chemical precipitation method. The obtained materials were analysed by physical-chemical methods, while the compositional and structural characteristics of hydroxyapatite-alendronate phases were determined by a combination of crystallographic, spectroscopic and thermal analysis investigations; moreover, the alendronate content, its maximal incorporation efficiency to hydroxyapatite and stability were determined. A two-level full factorial design was chosen to determine the optimum set of process parameters (synthesis temperature, reactant addition rate and ripening time) and their effects on various hydroxyapatite-alendronate characteristics: alendronate incorporation efficiency, hydroxyapatite crystallite size (XRD), hydroxyapatite particle size distribution (DLS). These effects were quantified using design of experiments. The in vitro release profile of alendronate from hydroxyapatite-alendronate tablets was assessed. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effect of strontium (Sr) doping into hydroxyapatite (HA) powders. It is well known that strontium promotes bone formation, reduces bone resorption and it is used to treat osteoporotic diseases as stated previously by researchers. Strontium-doped HA (Sr-HA) was produced by precipitation with increasing amount of ion exchange between calcium (Ca) and Sr. Two different Sr amounts as 2 and 4 mol% were doped into HA by adding Sr(NO) to the reaction solution. The precipitated HA was separated from supernatant after the vacuum filtration. The filtered wet cake of HA was exposed to spray drying and calcined in an air furnace at 1200 °C. The produced-HA powders were analyzed by using SEM, FTIR, XRD and TG-DSC techniques. At the end of the study, the results showed that decomposition of HA to tri-calcium phosphate increases with increasing Sr content. Thermal analyses revealed that Sr-doped HA powders loose more mass than pure HA powders. [ABSTRACT FROM AUTHOR]

Surface modification techniques have been applied to generate titanium implant surfaces that promote osseointegration for use in dental applications. In this study, strontium-doped brushite coatings were deposited on titanium by electrochemical deposition. The phase composition of the coating was investigated by energy dispersive X-ray spectroscopy and X-ray diffraction. The surface morphologies of the coatings were studied through scanning electron microscopy, and the cytocompatibility and bioactivity of the strontium-doped brushite coatings were evaluated using cultured osteoblasts. Osteoblast proliferation was enhanced by the addition of strontium, suggesting a possible mechanism by which strontium incorporation in brushite coatings increased bone formation surrounding the implants. Cell growth was also strongly influenced by the composition of the deposited coatings, with a 10% Sr-doped brushite coating inducing the greatest amount of bone formation among the tested materials. [ABSTRACT FROM AUTHOR]

Highly crystalline (∼80%) yet porous (∼20%) hydroxyapatite (HAp) coating was developed on surgical grade SS316L substrate by the microplasma spraying (MIPS) technique. Phase analysis and microstructural characterisations were carried out by X-ray diffraction, scanning electron microscopy and field emission scanning electron microscopy. Nanohardness and Young's modulus were measured by the nanoindentation technique at 100 mN load. Further, the HAp coatings were immersed in simulated body fluid (SBF) environment for 1–14 days to investigate their in vitro properties. Finally, single pass microscratch test was also conducted on the MIPS-HAp coatings after immersion in SBF. [ABSTRACT FROM AUTHOR]

This review discusses the origins and evolution of the MAPLE technique as it started as an alternative to spray coating of thin films for chemical vapor sensors. It describes its numerous applications for the deposition of thin films of polymeric, organic and biomaterials for various applications. This is followed by an overview of several new variations of the MAPLE technique. This review concludes with an outlook on the future of this highly versatile and successful vapor deposition process. [ABSTRACT FROM AUTHOR]