ENVIRONMENTAL FOOTPRINT AND MATERIAL COMPOSITION COMPARISON OF SINGLE-USE AND REUSABLE DUODENOSCOPES.

BACKGROUND: Infection outbreaks associated with contaminated reusable duodenoscopes (RDs) have induced the development of novel single-use duodenoscopes (SDs). This study aims to analyse the material composition and life cycle assessment (LCA) of RDs and SDs to assess the sustainability of global and partial SD implementation. METHODS: A single-centre study evaluated material composition analysis and LCA of one RD and two SDs from different manufacturers (A, B). Material composition analysis was performed to evaluate the thermochemical properties of the duodenoscope components. Carbon footprint was calculated using environmental software. We compared the sustainability strategies of universal use of RDs, frequent use of RDs with occasional SDs, and universal use of SDs over the lifetime of one RD. RESULTS: RDs were substantially heavier (3489 g) than SD-A (943 g) and SD-B (715.5 g). RDs were mainly metallic alloys (95%), whereas SDs were mainly plastic polymers and resins (70-81%). The LCA demonstrated the sustainability of RDs, with a lifecycle carbon footprint 62-82 times lower compared to the universal use of SDs (151.7 vs. 10512-12640 kg CO2-eq) and 10 times lower compared to the occasional use of SDs (151.7 vs. 1417.3-1676.6 kg CO2-eq). Differences were observed between SD-A and SD-B (7.9 vs. 6.6 kg CO2-eq per endoscope). End-of-life incineration emissions for SDs were the most environmental contributors. CONCLUSIONS: Widespread adoption of SD has greater environmental challenges; it requires a balance between infection control and environmental responsibility. Carbon footprint labelling can help healthcare institutions make sustainable choices and promote environmentally responsible healthcare practices.

Materials Science Toolkit for Carbon Footprint Assessment: A Case Study for Endoscopic Accessories of Common Use.

Ironically, healthcare systems are key agents in respiratory-related diseases and estimated deaths because of the high impact of their greenhouse gas emissions, along with industry, transportation, and housing. Based on safety requirements, hospitals and related services use an extensive number of consumables, most of which end up incinerated at the end of their life cycle. A thorough assessment of the carbon footprint of such devices typically requires knowing precise information about the manufacturing process, which is rarely available in detail because of the many materials, pieces, and steps involved during the fabrication. Yet, the tools most often used for determining the environmental impact of consumer goods require a bunch of parameters, mainly based on the material composition of the device. Here, we report a basic set of analytical methods that provide the information required by the software OpenLCA to calculate the main outcome related to environmental impact, greenhouse gas emissions. Through thermogravimetry, calorimetry, infrared spectroscopy, and elemental analysis, we proved that obtaining relevant data for the calculator in the exemplifying case of endoscopy tooling or accessories is possible. This routine procedure opens the door to a broader, more accurate analysis of the environmental impact of everyday work at hospital services, offering potential alternatives to minimize it.

Life cycle assessment of routinely used endoscopic instruments and simple intervention to reduce our environmental impact.

OBJECTIVES: GI endoscopy units represent the third largest producers of medical waste. We aimed to determine endoscopic instrument composition and life cycle assessment (LCA) and to assess a sustainability proposal based on a mark on the instruments that identifies parts can be safely recycled or 'green mark'. DESIGN: Material composition analysis and LCA of forceps, snares and clips from four different manufacturers (A-D) were performed with four different methods. Carbon footprint from production, transportation and end of life of these instruments was calculated. In 30 consecutive procedures, we marked the contact point with the working channel. 5 cm away from that point was considered as green mark. One-week prospective study was conducted with 184 procedures evaluating 143 instruments (75 forceps, 49 snares and 19 haemoclips) to assess the efficacy of this recyclable mark. RESULTS: Composition from different manufacturers varied widely. Most common materials were high global warming potential (GWP) waste (polyethylene, polypropylene and acrylonitrile) and low GWP waste (stainless steel). Significant differences were found for the forceps (0.31-0.47 kg of CO2 equivalent (CO2-eq)) and haemoclips (0.41-0.57 kg CO2-eq) between the manufacturers. Green mark was established 131.26 cm for gastroscope and 195.32 cm for colonoscope. One-week activity produced 67.74 kg CO2-eq. Applying our sustainability intervention, we could reduce up to 27.44% (18.26 kg CO2-eq). This allows the recycling of 61.7% of the instrument total weight (4.69 kg). CONCLUSION: Knowledge of carbon footprint is crucial to select the most sustainable alternatives because there are large variations between brands. A mark to identify recyclable parts could reduce our environmental impact significantly.

Development and evaluation of hyaluronan nanocomposite conduits for neural tissue regeneration.

Hyaluronan-based hydrogels are among the most promising neural tissue engineering materials because of their biocompatibility and the immunomodulation capabilities of their degradation byproducts. Despite these features, the problems related to their handling and mechanical properties have not yet been solved. In the present work it is proposed to address these drawbacks through the development of nanohybrid materials in which different nanometric phases (carbon nanotubes, mesoporous silica nanoparticles) are embedded in a crosslinked hyaluronan matrix. These nanohybrid matrices were next processed in the shape of cylindrical conduits aimed at promoting and improving neural stem cell differentiation and regeneration in neural tracts. These constructs could be of use specifically for peripheral nerve regeneration. Results of the study show that the inclusion of the different phases improved physico-chemical features of the gel such as its relative electrical permittivity, water intake and elastic modulus, giving hints on how the nanometric phase interacts with hyaluronan in the composite as well as for their potential in combined therapeutic approaches. Regarding the in vitro biological behavior of the hybrid tubular scaffolds, an improved early cell adhesion and survival of Schwann cells in their lumen was found, as compared to conduits made of pure hyaluronan gels. Furthermore, the differentiation and survival of neural precursors was not compromised, despite alleged safety concerns.

Role of Curing Temperature of Poly(Glycerol Sebacate) Substrates on Protein-Cell Interaction and Early Cell Adhesion.

A novel procedure to obtain smooth, continuous polymeric surfaces from poly(glycerol sebacate) (PGS) has been developed with the spin-coating technique. This method proves useful for separating the effect of the chemistry and morphology of the networks (that can be obtained by varying the synthesis parameters) on cell-protein-substrate interactions from that of structural variables. Solutions of the PGS pre-polymer can be spin-coated, to then be cured. Curing under variable temperatures has been shown to lead to PGS networks with different chemical properties and topographies, conditioning their use as a biomaterial. Particularly, higher synthesis temperatures yield denser networks with fewer polar terminal groups available on the surface. Material-protein interactions were characterised by using extracellular matrix proteins such as fibronectin (Fn) and collagen type I (Col I), to unveil the biological interface profile of PGS substrates. To that end, atomic force microscopy (AFM) images and quantification of protein adsorbed in single, sequential and competitive protein incubations were used. Results reveal that Fn is adsorbed in the form of clusters, while Col I forms a characteristic fibrillar network. Fn has an inhibitory effect when incubated prior to Col I. Human umbilical endothelial cells (HUVECs) were also cultured on PGS surfaces to reveal the effect of synthesis temperature on cell behaviour. To this effect, early focal adhesions (FAs) were analysed using immunofluorescence techniques. In light of the results, 130 °C seems to be the optimal curing temperature since a preliminary treatment with Col I or a Fn:Col I solution facilitates the formation of early focal adhesions and growth of HUVECs.

Influence of pre-polymerisation atmosphere on the properties of pre- and poly(glycerol sebacate).

Poly(glycerol sebacate) (PGS) is a versatile biodegradable biomaterial on account of its adjustable mechanical properties as an elastomeric polyester. Nevertheless, it has shown dissimilar results when synthesised by different research groups under equivalent synthesis conditions. This lack of reproducibility proves how crucial it is to understand the effect of the parameters involved on its manufacturing and characterize the polymer networks obtained. Several studies have been conducted in recent years to understand the role of temperature, time, and the molar ratio of its monomers, while the influence of the atmosphere applied during its pre-polymerisation remained unknown. The results obtained here allow for a better understanding about the effect of inert (Ar and N2) and oxidative (oxygen, dry air, and humid air) atmospheres on the extent of the reaction. The molecular pattern of intermediate pre-polymers and the gelation time and morphology of their corresponding cured PGS networks were studied as well. Overall, inert atmospheres promote a rather linear growth of macromers, with scarce branches, resulting in loose elastomers with long chains mainly crosslinked. Conversely, oxygen in the latter atmospheres promotes branching through secondary hydroxyl groups, leading to less-crosslinked 'defective' networks. In this way, the pre-polymerisation atmosphere could be used advantageously to adjust the reactivity of secondary hydroxyls, in order to modulate branching in the elastomeric PGS networks obtained to suit the properties required in a particular application.

Amphipathic Substrates Based on Crosslinker-Free Poly(ε-Caprolactone):Poly(2-Hydroxyethyl Methacrylate) Semi-Interpenetrated Networks Promote Serum Protein Adsorption.

A simple procedure has been developed to synthesize uncrosslinked soluble poly(hydroxyethyl methacrylate) (PHEMA) gels, ready for use in a subsequent fabrication stage. The presence of 75 wt % methanol (MetOH) or dimethylformamide (DMF) impedes lateral hydroxyl-hydroxyl hydrogen bonds between PHEMA macromers to form during their solution polymerization at 60 °C, up to 24 h. These gels remain soluble when properly stored in closed containers under cold conditions and, when needed, yield by solvent evaporation spontaneous physically-crosslinked PHEMA adapted to the mould used. Moreover, this two-step procedure allows obtaining multicomponent systems where a stable and water-affine PHEMA network would be of interest. In particular, amphiphilic polycaprolactone (PCL):PHEMA semi-interpenetrated (sIPN) substrates have been developed, from quaternary metastable solutions in chloroform (CHCl3):MetOH 3:1 wt. and PCL ranging from 50 to 90 wt % in the polymer fraction (thus determining the composition of the solution). The coexistence of these countered molecules, uniformly distributed at the nanoscale, has proven to enhance the number and interactions of serum protein adsorbed from the acellular medium as compared to the homopolymers, the sIPN containing 80 wt % PCL showing an outstanding development. In accordance to the quaternary diagram presented, this protocol can be adapted for the development of polymer substrates, coatings or scaffolds for biomedical applications, not relying upon phase separation, such as the electrospun mats here proposed herein (12 wt % polymer solutions were used for this purpose, with PCL ranging from 50% to 100% in the polymer fraction).

Candidate Polyurethanes Based on Castor Oil (Ricinus communis), with Polycaprolactone Diol and Chitosan Additions, for Use in Biomedical Applications.

Polyurethanes are widely used in the development of medical devices due to their biocompatibility, degradability, non-toxicity and chemical versatility. Polyurethanes were obtained from polyols derived from castor oil, and isophorone diisocyanate, with the incorporation of polycaprolactone-diol (15% w/w) and chitosan (3% w/w). The objective of this research was to evaluate the effect of the type of polyol and the incorporation of polycaprolactone-diol and chitosan on the mechanical and biological properties of the polyurethanes to identify the optimal ones for applications such as wound dressings or tissue engineering. Polyurethanes were characterized by stress-strain, contact angle by sessile drop method, thermogravimetric analysis, differential scanning calorimetry, water uptake and in vitro degradation by enzymatic processes. In vitro biological properties were evaluated by a 24 h cytotoxicity test using the colorimetric assay MTT and the LIVE/DEAD kit with cell line L-929 (mouse embryonic fibroblasts). In vitro evaluation of the possible inflammatory effect of polyurethane-based materials was evaluated by means of the expression of anti-inflammatory and proinflammatory cytokines expressed in a cellular model such as THP-1 cells by means of the MILLIPLEX® MAP kit. The modification of polyols derived from castor oil increases the mechanical properties of interest for a wide range of applications. The polyurethanes evaluated did not generate a cytotoxic effect on the evaluated cell line. The assessed polyurethanes are suggested as possible candidate biomaterials for wound dressings due to their improved mechanical properties and biocompatibility.

Influence of synthesis parameters on hyaluronic acid hydrogels intended as nerve conduits.

Hydrogels have widely been proposed lately as strategies for neural tissue regeneration, but there are still some issues to be solved before their efficient use in tissue engineering of trauma, stroke or the idiopathic degeneration of the nervous system. In a previous work of the authors a novel Schwann-cell structure with the shape of a hollow cylinder was obtained using a three-dimensional conduit based in crosslinked hyaluronic acid as template. This original engineered tissue of tightly joined Schwann cells obtained in a conduit lumen having 400 µm in diameter is a consequence of specific cell-material interactions. In the present work we analyze the influence of the hydrogel concentration and of the drying process on the physicochemical and biological performance of the resulting tubular scaffolds, and prove that the cylinder-like cell sheath obtains also in scaffolds of a larger inner diameter. The diffusion of glucose and of the protein BSA through the scaffolds is studied and characterized, as well as the enzymatic degradation kinetics of the lyophilized conduits. This can be modulated from a couple of weeks to several months by varying the concentration of hyaluronic acid in the starting solution. These findings allow to improve the performance of hyaluronan intended for neural conduits, and open the way to scaffolds with tunable degradation rate adapted to the site and severity of the injury.