Review article laser-induced hyperthermia on graphene oxide composites

Background: Hyperthermia-based therapies have shown great potential for clinical applications such as for the antitumor and antipathogenic activities. Within all strategies, the so-called photothermal therapy proposes to induce the hyperthermia by the remote laser radiation on a photothermal conversion agent, in contact with the target tissue. Methods: This paper reviews the most relevant in vitro and in vivo studies focused on NIR laser-induced hyperthermia due to photoexcitation of graphene oxide (GO) and reduced graphene oxide (rGO). Relevant parameters such as the amount of GO/rGO, the influence of the laser wavelength and power density are considered. Moreover, the required temperature and exposure time for each antitumor/antipathogenic case are collected and unified in a thermal dose parameter: the CEM43. Results: The calculated CEM43 thermal doses revealed a great variability for the same type of tumor/strain. In order to detect potential tendencies, the values were classified into four ranges, varying from CEM4360ºC). Conclusions: The ability of GO/rGO as effective photothermal conversion agents to promote a controlled hyperthermia is proven. The variability found for the CEM43 thermal doses on the reviewed studies reveals the potentiality to evaluate, for each application, the use of lower temperatures, by modulating time and/or repetitions in the dosesMinisterio de Ciencia e Innovación del Gobierno de España | Ref. BIOHEAT (PID 2020- 115415RB-100)Xunta de Galicia | Ref. GRC (ED431C 2021/49

Physicochemical properties of 3D-printed polylactic acid/hydroxyapatite scaffolds

The reconstruction or regeneration of damaged bone tissue is one of the challenges of orthopedic surgery and tissue engineering. Among all strategies investigated, additive manufacturing by fused deposition modeling (3D-FDM printing) opens the possibility to obtain patient-specific scaffolds with controlled architectures. The present work evaluates in depth 3D direct printing, avoiding the need for a pre-fabricated filament, to obtain bone-related scaffolds from direct mixtures of polylactic acid (PLA) and hydroxyapatite (HA). For it, a systematic physicochemical characterization (SEM-EDS, FT-Raman, XRD, micro-CT and nanoindentation) was performed, using different PLA/HA ratios and percentages of infill. Results prove the versatility of this methodology with an efficient HA incorporation in the 3D-printed scaffolds up to 13 wt.% of the total mass and a uniform distribution of the HA particles in the scaffold at the macro level, both longitudinal and cross sections. Moreover, an exponential distribution of the HA particles from the surface toward the interior of the biocomposite cord (micro level), within the first 80 µm (10% of the entire cord diameter), is also confirmed, providing the scaffold with surface roughness and higher bioavailability. In relation to the pores, they can range in size from 250 to 850 µm and can represent a percentage, in relation to the total volume of the scaffold, from 24% up to 76%. The mechanical properties indicate an increase in Young’s modulus with the HA content of up to ~50%, compared to the scaffolds without HA. Finally, the in vitro evaluation confirms MG63 cell proliferation on the 3D-printed PLA/HA scaffolds after up to 21 days of incubation

Vancomycin-loaded 3D-printed polylactic acid–hydroxyapatite scaffolds for bone tissue engineering

The regeneration of bone remains one of the main challenges in the biomedical field, with the need to provide more personalized and multifunctional solutions. The other persistent challenge is related to the local prevention of infections after implantation surgery. To fulfill the first one and provide customized scaffolds with complex geometries, 3D printing is being investigated, with polylactic acid (PLA) as the biomaterial mostly used, given its thermoplastic properties. The 3D printing of PLA in combination with hydroxyapatite (HA) is also under research, to mimic the native mechanical and biological properties, providing more functional scaffolds. Finally, to fulfill the second one, antibacterial drugs locally incorporated into biodegradable scaffolds are also under investigation. This work aims to develop vancomycin-loaded 3D-printed PLA–HA scaffolds offering a dual functionality: local prevention of infections and personalized biodegradable scaffolds with osseointegrative properties. For this, the antibacterial drug vancomycin was incorporated into 3D-printed PLA–HA scaffolds using three loading methodologies: (1) dip coating, (2) drop coating, and (3) direct incorporation in the 3D printing with PLA and HA. A systematic characterization was performed, including release kinetics, Staphylococcus aureus antibacterial/antibiofilm activities and cytocompatibility. The results demonstrated the feasibility of the vancomycin-loaded 3D-printed PLA–HA scaffolds as drug-releasing vehicles with significant antibacterial effects for the three methodologies. In relation to the drug release kinetics, the (1) dip- and (2) drop-coating methodologies achieved burst release (first 60 min) of around 80–90% of the loaded vancomycin, followed by a slower release of the remaining drug for up to 48 h, while the (3) 3D printing presented an extended release beyond 7 days as the polymer degraded. The cytocompatibility of the vancomycin-loaded scaffolds was also confirmed.Agencia Estatal de Investigación | Ref. PID2020-115415RB-I00Xunta de Galicia | Ref. ED431C 2021/49Xunta de Galicia | Ref. ED481A 2019/31

3D-printed PLA medical devices: physicochemical changes and biological response after sterilisation treatments

Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGPolylactic acid (PLA) has become one of the most commonly used polymers in medical devices given its biocompatible, biodegradable and bioabsorbable properties. In addition, due to PLA’s thermoplastic behaviour, these medical devices are now obtained using 3D printing technologies. Once obtained, the 3D-printed PLA devices undergo different sterilisation procedures, which are essential to prevent infections. This work was an in-depth study of the physicochemical changes caused by novel and conventional sterilisation techniques on 3D-printed PLA and their impact on the biological response in terms of toxicity. The 3D-printed PLA physicochemical (XPS, FTIR, DSC, XRD) and mechanical properties as well as the hydrophilic degree were evaluated after sterilisation using saturated steam (SS), low temperature steam with formaldehyde (LTSF), gamma irradiation (GR), hydrogen peroxide gas plasma (HPGP) and CO2 under critical conditions (SCCO). The biological response was tested in vitro (fibroblasts NCTC-929) and in vivo (embryos and larvae wild-type zebrafish Danio rerio). The results indicated that after GR sterilisation, PLA preserved the O:C ratio and the semi-crystalline structure. Significant changes in the polymer surface were found after HPGP, LTSF and SS sterilisations, with a decrease in the O:C ratio. Moreover, the FTIR, DSC and XRD analysis revealed PLA crystallisation after SS sterilisation, with a 52.9% increase in the crystallinity index. This structural change was also reflected in the mechanical properties and wettability. An increase in crystallinity was also observed after SCCO and LTSF sterilisations, although to a lesser extent. Despite these changes, the biological evaluation revealed that none of the techniques were shown to promote the release of toxic compounds or PLA modifications with toxicity effects. GR sterilisation was concluded as the least reactive technique with good perspectives in the biological response, not only at the level of toxicity but at all levels, since the 3D-printed PLA remained almost unaltered.POCTEP INTERREG España- Portugal | Ref. BLUEBIOLABInterreg Atlantic Area | Ref. BLUEHUMAN EAPA_151/2016Ministerio de Ciencia e Innovación | Ref. PID 2020-115415RB-100Xunta de Galicia | Ref. ED431C 2021/49Xunta de Galicia | Ref. ED481A 2019/314Xunta de Galicia | Ref. IN606A-2017/011Fundação para a Ciência e a Tecnologia | Ref. UIDB/50016/202

How to sterilize polylactic acid based medical devices?

How sterilization techniques accurately affect the properties of biopolymers continues to be an issue of discussion in the field of biomedical engineering, particularly now with the development of 3D-printed devices. One of the most widely used biopolymers in the manufacture of biomedical devices is the polylactic acid (PLA). Despite the large number of studies found in the literature on PLA devices, relatively few papers focus on the effects of sterilization treatments on its properties. It is well documented in the literature that conventional sterilization techniques, such as heat, gamma irradiation and ethylene oxide, can induced damages, alterations or toxic products release, due to the thermal and hydrolytical sensitivity of PLA. The purposes of this paper are, therefore, to review the published data on the most common techniques used to sterilize PLA medical devices and to analyse how they are affecting their physicochemical and biocompatible properties. Emerging and alternative sterilization methods for sensitive biomaterials are also presented.Xunta de Galicia | Ref. ED481A 2019/314Interreg Atlantic Area | Ref. EAPA_151/201

Hydroxyapatite scaffolds derived from deer antler: Structure dependence on processing temperature

Discarded antlers from deer are proposed as a promising alternative CaP-based bone graft to fulfil specific unsolved clinical requirements, such as osteoinductive properties or an optimal balance in stability/resorbability. Moreover, depending on the location of the bone defect and the type of bone lost (cortical versus cancellous), adequate morphological/mechanical properties for indicated biomaterials are needed. At the present work a detailed study of the physicochemical properties of two bioceramics obtained from the cortical and the trabecular sections of deer antler is presented. The influence of temperature on both bioceramics was also evaluated in depth to guarantee removal of organic material, analyze the compositional changes for high temperatures (up to 1100 °C) and study how their specific morphological features can influence these modifications. Morphological evaluation (SEM, porosity) of both final bioapatites (cortical and trabecular) was assessed, together with composition (ICP-OES, EDS, FT-Raman, XRD, TEM) and mechanical properties (nano-indentation). Optimal temperature for calcination was selected, through a thermogravimetric analysis, to ensure: the removal of organic material and a re-crystallization process (carbonate group decomposition) in both sections. Main contribution of hydroxyapatite (Ca5(PO4)3(OH)) in hexagonal phase was found, structure similar to human bone, with the presence of periclase (MgO). A Ca/P ratio in the same range as porcine and bovine bones, and with trace elements, such as Mg and Na, that play relevant roles in osteogenic metabolism was also detected. The dense and compact structure in cortical section and the spongy-like structure in the trabecular one, with pores >200 μm in diameter occupying a surface of 52 ± 8% were characterized. Related to these morphological properties, the same calcination temperature was proven to yield larger crystals in the trabecular section, given the higher availability of space for the crystal to grow (lower density of material).Xunta de Galicia | Ref. ED431C 2017_51Xunta de Galicia | Ref. ED431D 2017/13INTERREG V España-Portugal (POCTEP) | Ref. 0245 IBEROS1

Structural characterization of bioceramics and mineralized tissues based on Raman and XRD techniques

The design of new bioceramics requires a deep understanding of their structural characteristics using a combination of different characterization techniques. This paper offers an exhaustive Raman spectroscopy and X-ray diffraction study of two groups of bioceramics natural and synthetic, as well as of living tissues with different degrees of mineralization. Based on these results, two Raman-XRD correlation charts are proposed. Using a single Raman measurement, these charts are valuable tools for the identification of a number of structural parameters, such as the apatite phase percentage or crystallite size, of different calcium phosphate-based bioceramics and mineralized tissues.Xunta de Galicia-FEDER | Ref. GRC2013-008 and R2014/033European Commission| Ref. FP7/REGPOT- 2012–2013.1, n.316265 BIOCAP

Application of shark teeth–derived bioapatites as a bone substitute in veterinary orthopedics. Preliminary clinical trial in dogs and cats

Background: The autograft is still considered the gold standard for the treatment of bone defects. However, given the significant morbidity of the donor site with which it has been associated, alternative substitutes for bone grafts have been developed. In the present study, a bone substitute composed of CaP biphasic bioceramics obtained from shark teeth was used (BIOFAST-VET). Objective: The objective of this study is to evaluate the efficacy of a marine bioapatite in the veterinary clinical field using it as a bone-grafting scaffold in dogs and cats. Methods: The biomaterial was randomly distributed in 6 veterinary clinical centers in Spain and was used in 24 cases (20 dogs and 4 cats) including 14 fractures, 9 arthrodesis, and 1 bone cyst. Grains between 500 and 2,000μm were used. Inclusion and exclusion criteria were established. The time of consolidation and functional recovery were quantitatively and qualitatively assessed. For this, a follow-up was carried out at 2, 4, 8, and 12 weeks, included radiographic images, physical examination and sharing the feedback with the owners. Results: Nineteen cases completed the study (18 dogs and 1 cat; 11 fractures, 7 arthrodesis, and 1 bone cyst). The remaining five were excluded because they did not complete the radiographic follow-up (three cats and two dogs), being three arthrodesis and two fractures. In 18 of 19 cases, the use of the biomaterial was successful; the remaining one failed due to causes not related to the biomaterial. There were no systemic or local adverse reactions. Eighteen patients had a good functional recovery. The average consolidation time was 5.94 weeks in dogs with fractures and arthrodesis, not finding statistically significant differences between sex, weight, and procedure. Conclusions: This biomaterial is presented as a very suitable candidate for orthopedic surgery in the veterinary field. Preliminary results showed that its use reduces consolidation time in dogs with fractures and arthrodesis. In addition, no adverse systemic or local reactions have been observed derived from its use.INTERREG | Ref. 0245 IBEROS1EINTERREG | Ref. 0302 CVMARI1PINTERREG-ATLANTIC AREA | Ref. EAPA_151/2016 BLUEHUMANGAIN | Ref. IN855A2016/06Xunta de Galicia | Ref. ED431C 2017_51Xunta de Galicia | Ref. ED431D 2017/13Xunta de Galicia | Ref. ED431C 2017/3

Case Report: First evidence of a benign bone cyst in an adult Teckel dog treated with shark teeth-derived bioapatites

Bone cysts are a very rare orthopedic pathology in veterinary medicine, the general prevalence of which is unknown. A unicameral bone cyst was diagnosed in an adult female Teckel dog with a limp that was treated surgically by filling the defect with marine bioapatites. The treatment was effective and at 8 weeks the defect had remodeled 50.24%. Eighteen months after surgery, the defect had remodeled 94.23%. The limp disappeared after surgery, and functional recovery was good in all stages after surgery. No adverse reactions were observed at the local or systemic level. This is the first report of a benign bone cyst in an lame adult female Teckel successfully treated with a novel marine bioapatite.Axencia Galega de Innovación | Ref. IN855A2016/06Xunta de Galicia | Ref. ED431C 2017_51Xunta de Galicia | Ref. ED431D 2017/13Xunta de Galicia | Ref. ED431C 2017/37INTERREG-ATLANTIC AREA | Ref. EAPA_151/2016 BLUEHUMANINTERREG | Ref. 0245 IBEROS1EINTERREG | Ref. 0302 CVMARI1