Safe-by-design strategies applied to scaffold hybrid manufacturing

The EU-project FAST (GA 685825) has developed a 3D printer machine prototype for the manufacture of bone implants (scaffolds), by merging masterbatches of biodegradable polymer poly(ethylene oxide)terephthalate/poly(butylene terephthalate) [PEOT/PBT] doped with nanofillers [reduced graphene oxide (rGO), hydroxyapatite (HA) and magnesium aluminium hydroxide ciprofloxacin hydrotalcite (LDH-CFX)], and atmospheric plasma technology. This paper focus on the safe design strategies identified by FAST to address the risk to health resulting from the potential airborne emission of nano-objects and their aggregates and agglomerates (NOAAs) by the 3D printer prototype, which might result in occupational exposures by inhalation. The work also includes measurements of airborne emissions and occupational exposures carried out during the verification stage of the prototype design. Nanofillers particles (rGO, n-HA, LDH-CFX) were not observed, neither at source nor in the working area, suggesting no release of free nanofillers to the air one they have been embedded in the polymer masterbatch. Additionally, the exposure in the workplace was far below the selected Occupational Exposure Levels (OELs), for total particle number concentration (PNC), dust, elemental carbon (EC) and volatile organic compounds (VOCs). The results showed that, when working with the current prototype in normal operation (for its intended use) and with controls enabled [enclosure with the doors closed and Local Exhaust Ventilation (LEV) activated], the emission from the machine and the worker's exposure to NOAAs are well controlled.The project FAST received funding from the European Union’s Horizon 2020 research and innovation programme, under grant agreement Nº 685825. This paper reflects only the authors’ views, and the Commission is not responsible for any use that may be made of the information contained therein

Surface chemistry and bioactivity of colloidal particles from industrial kraft lignins

The morphology control of lignin through particle size reduction to nanoscale seems to be a suitable conversion technology to overcome the intrinsic limitations of its native form to develop a wide range of biomaterials with high performance. Colloidal lignin particles (CLPs) in the range of 150–200 nm were synthesised from hardwood and softwood kraft lignins by the solvent shifting method. The initial molecular features of kraft lignins were evaluated in terms of purity, molecular weight distribution, and chemical functionalities. The impact of the lignin source and structure on the morphology, size distribution, and surface chemistry of CLPs was evaluated by particle size analyser, SEM, TEM and 1H NMR. The results evidenced the influence of the botanical origin on the morphology and surface chemistry of particles. Furthermore, the antioxidant properties and cytotoxicity of lignins and corresponding CLPs, towards lung fibroblast cells were compared. CLPs from hardwood kraft lignins exhibited higher antioxidant power against DPPH free radical and a higher cytotoxic effect (IC30 = 67–70 μg/mL) against lung fibroblast when compared to CLPs from softwood kraft lignin (IC30 = ~91 μg/mL). However, the cytotoxicity of these biomaterials was dose-dependent, suggesting their potential application as active ingredients in cosmetic and pharmaceutic products at low concentrations.This research was funded by the European Commission's funding of the InnoRenew project (Grant Agreement #739574 under the Horizon 2020 WIDESPREAD-2-Teaming program) and the Republic of Slovenia (investment funding from the Republic of Slovenia and the European Regional Development Fund). O.G. is grateful for the financial Support received from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Action for development of the BIO4CARE project (Grant Number #101023389). The contribution of COST Action LignoCOST (CA17128), supported by COST (European Cooperation in Science and Technology, www.cost.eu), in promoting interaction, exchange of knowledge and collaboration in the field of lignin valorisation is gratefully acknowledged. O.S. is grateful to the Knut and Alice Wallenberg Foundation for financial support through the Wallenberg Wood Science Center at KTH Royal Institute of Technology. H.L. acknowledges The China Scholarship Council and Wood and Pulping Chemistry Research Network (WPCRN) at KTH for the financial support of her doctorate study

Assessment of nanoparticles release into the environment during drilling of carbon nanotubes/epoxy and carbon nanofibres/epoxy nanocomposites

The risk assessment, exposure and understanding of the release of embedded carbon nanotubes (CNTs) and carbon nanofibers (CNFs) from commercial high performance composites during machining processes are yet to be fully evaluated and quantified. In this study, CNTs and CNFs were dispersed in epoxy matrix through calendaring process to form nanocomposites. The automated drilling was carried out in a specially designed drilling chamber that allowed elimination of background noise from the measurements. Emission measurements were taken using condensed particle counter (CPC), scanning mobility particle sizer (SMPS) and DMS50 Fast Particulate Size Spectrometer. In comparison to the neat epoxy, the study results revealed that the nano-filled samples produced an increase of 102% and 227% for the EP/CNF and EP/CNT sample respectively in average particle number concentration emission. The particle mass concentration indicated that the EP/CNT and EP/CNF samples released demands a vital new perspective on CNTs and CNFs embedded within nanocomposite materials to be considered and evaluated for occupational exposure assessment. Importantly, the increased concentration observed at 10 nm aerosol particle sizes measurements strongly suggest that there are independent CNTs being released at this range.The work is funded by and part of the European Commission Life project named Simulation of the release of nanomaterials from consumer products for environmental exposure assessment (SIRENA, Pr. No. LIFE 11 ENV/ES/596). We are also thankful to the funding by QualityNano Project through Transnational Access (TA Application VITO-TAF-382 and VITO-TAF-500) under the European Commission, Grant Agreement No: INFRA-2010-262163 for the access and use of the facilities at the Flemish Institute for Technological Research (VITO). The authors would like to acknowledge K. Tirez and R. Persoons at Vito for their XRF and SEM support. Kristof Starost is also thankful for partial funding by the School of Engineering for his studentship

The effect of nanosilica (SiO2) and nanoalumina (Al2O3) reinforced polyester nanocomposites on aerosol nanoparticle emissions into the environment during automated drilling

The aim of this study is to investigate the effect nanosilica and nanoalumina has on nanoparticle release from industrial nanocomposites due to drilling for hazard reduction whilst simultaneously obtaining the necessary mechanical performance. This study is therefore specifically designed such that all background noise is eliminated in the measurements range of 0.01 particles/cm3 and ±10% at 106 particles/cm3. The impact nano-sized SiO2 and Al2O3 reinforced polyester has on nanoparticle aerosols generated due to drilling is investigated. Real-time measurement was conducted within a specially designed controlled test chamber using a condensation particle counter (CPC) and a scanning mobility particle sizer spectrometer (SMPS). The results show that the polyester nanocomposite samples displayed statistically significant differences and an increase in nanoparticle number concentration by up to 228% compared to virgin polyester. It is shown that the nanofillers adhered to the polyester matrix showing a higher concentration of larger particles released (between 20 – 100 nm). The increase in nanoparticle reinforcement weight concentration and resulting nanoparticle release vary considerably between the nanosilica and nanoalumina samples due to the nanofillers presence. This study indicates a future opportunity to safer by design strategy that reduces number of particles released concentration and sizes without compromising desired mechanical properties for engineered polymers and composites.European Commission Life+ project named “Simulation of the release of nanomaterials from consumer products for environmental exposure assessment” (SIRENA, Pr. No. LIFE 11 ENV/ES/596). QualityNano Project through Transnational Access (TA Application VITO-TAF-382 and VITO-TAF-500) under the European Commission, Grant Agreement No: INFRA-2010-26216

3D additive manufactured composite scaffolds with antibiotic-loaded lamellar fillers for bone infection prevention and tissue regeneration

Bone infections following open bone fracture or implant surgery remain a challenge in the orthopedics field. In order to avoid high doses of systemic drug administration, optimized local antibiotic release from scaffolds is required. 3D additive manufactured (AM) scaffolds made with biodegradable polymers are ideal to support bone healing in non-union scenarios and can be given antimicrobial properties by the incorporation of antibiotics. In this study, ciprofloxacin and gentamicin intercalated in the interlamellar spaces of magnesium aluminum layered double hydroxides (MgAl) and α-zirconium phosphates (ZrP), respectively, are dispersed within a thermoplastic polymer by melt compounding and subsequently processed via high temperature melt extrusion AM (~190 °C) into 3D scaffolds. The inorganic fillers enable a sustained antibiotics release through the polymer matrix, controlled by antibiotics counterions exchange or pH conditions. Importantly, both antibiotics retain their functionality after the manufacturing process at high temperatures, as verified by their activity against both Gram + and Gram - bacterial strains. Moreover, scaffolds loaded with filler-antibiotic do not impair human mesenchymal stromal cells osteogenic differentiation, allowing matrix mineralization and the expression of relevant osteogenic markers. Overall, these results suggest the possibility of fabricating dual functionality 3D scaffolds via high temperature melt extrusion for bone regeneration and infection prevention.We are grateful to the FAST project funded under the H2020-NMP- PILOTS-2015 scheme (GA n. 685825) for financial support. Some of the materials used in this work were provided by the Texas A&M Health Science Center College of Medicine Institute for Regenerative Medicine at Scott & White through a grant from NCRR of the NIH (Grant #P40RR017447)

Particle emission measurements in three scenarios of mechanical degradation of polypropylene-nanoclay nanocomposites

Researchers and legislators have both claimed the necessity to standardize the exposure assessment of polymer nanocomposites throughout their life cycle. In the present study we have developed and compared three different and independent operational protocols to investigate changes in particle emission behavior of mechanically degraded polypropylene (PP) samples containing different fillers, including talc and two types of nanoclays (wollastonite-WO- and montmorillonite-MMT-) relative to not reinforced PP. Our results have shown that the mechanical degradation of PP, PP-Talc, PP-WO and PP-MMT samples causes the release of nano-sized particles. However, the three protocols investigated, simulating industrial milling and drilling and household drilling, have produced different figures for particles generated. Results suggest that it is not possible to describe the effects of adding nano-sized modifiers to PP by a single trend that applies consistently across all different protocols. Differences observed might be attributed to a variety of causes, including the specific operational parameters selected for sample degradation and the instrumentation used for airborne particle release characterization. In particular, a streamlined approach for future assessments providing a measure for released particles as a function of the quantity of removed material would seem useful, which can provide a reference benchmark for the variations in the number of particles emitted across a wider range of different mechanical processes

State of the art in nanorelease assessment for polymer nanocomposites

<p>Introduction of Life+ Programme and SIRENA Project</p> <p> </p> <p>State of the art in nanorelease assessment for polymer nanocomposites</p

Toxicology review in metal nanoparticles: Approximation in gold and cobalt ferrite nanoparticles

The toxicity of nanoparticles is under discussion. The great diversity of nanoparticles (different chemical composition, size, shape, surface recovery among others) makes it difficult to establish a criterion for determining the effects of human and environmental exposure. Gold Nanoparticles are considered biocompatible because they are composed of an inert material. These nanoparticles are used for different medical purposes, such as labeling, delivering, heating and sensing. Their effects can vary depending on their coating, size, and shape. Nevertheless, inert particles can produce morphologic changes, loss of function, inflammation or cell damage, therefore they must be studied with more detail. Superparamagnetic properties of cobalt ferrite nanoparticles are used for biosensing applications, tumor treatment by hyperthermia and as contrast agent in magnetic resonance imaging (MRI) among other applications. Although they are also considered biocompatible, some studies show some degree of dose and size depending cytotoxicity and genotoxicity. Both kinds of nanoparticles, mainly focused to biomedical industry, have been studied in different fields of toxicology. In this paper we have summarized some reports in an interdisciplinary review.Peer reviewe