Correction: Environmentally responsive hydrogel composites for dynamic body thermoregulation.

Correction for 'Environmentally responsive hydrogel composites for dynamic body thermoregulation' by M. Garzón Altamirano et al., Soft Matter, 2023, 19, 2360-2369, https://doi.org/10.1039/D2SM01548J.

Environmentally responsive hydrogel composites for dynamic body thermoregulation.

Hydrogel composites exhibiting dynamic thermo-hydro responsive modulation of infrared radiation (IR) in the 5-15 µm range are designed for personalized body thermoregulation. Fabrication of the proposed system relies on the periodic arrangement of submicron-sized spherical fine silica (SiO2) particles within poly(N-isopropylacrylamide) (PNIPAM)-based hydrogels. The dependence of the SiO2 particles content on the IR reflection, followed by its modulation in response to any immediate environmental changes are thereby investigated. The addition of 20 wt% of SiO2 allowed the hydrogel composites to reflect 20% of the IR emitted by the human body at constant temperature (i.e. T = 20 °C) and relative humidity (i.e. RH = 0%). According to Bragg's law, we found that the smaller the distance between the SiO2 particles, the higher the IR reflection. The IR reflection further increased to a maximum of 42% when the resulting hydrogel composites are subjected to changes in relative humidity (i.e. RH = 60%) and temperature (i.e. T = 35 °C). Thermography is used to map the IR radiation emitted from the hydrogel composites when placed on the skin of the human body, demonstrating that the composite is actually reflecting IR. The latter results are supported by theoretical models that define the IR reflection profile of the resulting hydrogel composites with respect to the silica content, relative humidity and temperature.

Investigation of the parameters used in fused deposition modeling of poly(lactic acid) to optimize 3D printing sessions.

This study assesses the feasibility of printing implantable devices using 3D printing Fused deposition modeling (FDM) technology. The influence of the deposition temperature, the deposition rate and the layer thickness on the printing process and the physical properties of the devices were evaluated. The filaments were composed of neat poly(lactic acid) (PLA) and blends of different plasticizers (polyethylene glycol 400 (PEG 400), triacetine (TA), acetyltriethyl citrate (ATEC) and triethyl citrate (TEC)) at 10% (w/w). The assessment of thermomechanical characteristics and morphology of both filaments and devices (cylinders and dog bones) were performed. The influence of each parameter was evaluated using a design of experiment (DoE) and the significance of the results was discussed. A large amount of data about the evaluation of FDM process parameters are already available in the literature. However, specific insights needed to be increased into the impact of the use of PLA and plasticized PLA raw material on the feasibility of printing devices in three dimensions. To conclude, the ductility was improved with a high layer thickness, low temperature and using ATEC. Whereas, adhesion was promoted with an increase in temperature, a lower layer thickness and adding TA.

The role of curvature in Diels-Alder functionalization of carbon-based materials.

We have estimated theoretically the impact of curvature on the free energies of activation and reaction associated with Diels-Alder reactions on carbon-based materials. Significant reduction is observed for both energy values with increasing curvature for core-functionalization, while the opposite trend prevails for edge-functionalization, as further supported by SEM/fluorescence measurements.

Pyrene-end-functionalized poly(L-lactide) as an efficient carbon nanotube dispersing agent in poly(L-lactide): mechanical performance and biocompatibility study.

In order to improve the mechanical properties of poly(L-lactide) (PLLA) based implants, a study was made of how far well dispersed multi-walled carbon nanotubes (MWCNTs) within a PLLA matrix were able to positively affect these properties. To this end, pyrene-end-functionalized poly(L-lactide) (py-end-PLLA) was evaluated as a dispersing agent. Transmission electron microscopy (TEM) analyses and mechanical tests of MWCNTs-based materials demonstrated an enhancement of MWCNT dispersion in the PLLA matrix and improved Young's modulus (E) when 4 wt% of py-end-PLLA was used as the dispersing agent. Subsequently, the bioacceptance of PLLA/py-end-PLLA/MWCNTs nanocomposites was evaluated using human bone marrow stromal cells (HBMC) in vitro. The inclusion of py-end-PLLA and MWCNTs supported HBMC adhesion and proliferation. The expression levels of the bone-specific markers indicated that the cells kept their potential to undergo osteogenic differentiation. The results of this study indicate that the addition of MWCNT combined with py-end-PLLA in PLLA/py-end-PLLA/MWCNTs nanocomposites may widen the range of applications of PLLA within the field of bone tissue engineering thanks to their mechanical strength and cytocompatibility.

Osteoconductive and bioresorbable composites based on poly(L,L-lactide) and pseudowollastonite: from synthesis and interfacial compatibilization to in vitro bioactivity and in vivo osseointegration studies.

This contribution reports on the elaboration of novel bioresorbable composites consisting of pseudowollastonite (psW) (a silicate-based polycrystalline ceramic (α-CaSiO(3))) and poly(L,L-lactide) as a valuable polymeric candidate in bone-guided regeneration. These composites were prepared by direct melt-blending to avoid the use of organic solvents harmful for biomedical applications. Amphiphilic poly(ethylene oxide-b-L,L-lactide) diblock copolymers synthesized by ring-opening polymerization were added to psW-based composites to modulate the bioactivity of the composites. The bioactivity of the composites was first evaluated by monitoring the release of bioactive Ca(2+) and (SiO(4))(4-) ions as well as the concomitant formation of hydroxyapatite on the material surface after soaking them in physiological fluid. Subsequently, the composites were studied in vitro to evaluate their cytotoxicity in the presence of SaOS-2 osteoblastic cells and in vivo to assess their osteoconductivity in an orthotopic rat tibia model. This study provides a first insight into the use of direct melt-blended psW-poly(L,L-lactide) composites for bone-regeneration applications.