Solar ultraviolet light collector for germicidal irradiation on the moon.

Prolonged human-crewed missions on the Moon are foreseen as a gateway for Mars and asteroid colonisation in the next decades. Health risks related to long-time permanence in space have been partially investigated. Hazards due to airborne biological contaminants represent a relevant problem in space missions. A possible way to perform pathogens' inactivation is by employing the shortest wavelength range of Solar ultraviolet radiation, the so-called germicidal range. On Earth, it is totally absorbed by the atmosphere and does not reach the surface. In space, such Ultraviolet solar component is present and effective germicidal irradiation for airborne pathogens' inactivation can be achieved inside habitable outposts through a combination of highly reflective internal coating and optimised geometry of the air ducts. The Solar Ultraviolet Light Collector for Germicidal Irradiation on the Moon is a project whose aim is to collect Ultraviolet solar radiation and use it as a source to disinfect the re-circulating air of the human outposts. The most favourable positions where to place these collectors are over the peaks at the Moon's poles, which have the peculiarity of being exposed to solar radiation most of the time. On August 2022, NASA communicated to have identified 13 candidate landing regions near the lunar South Pole for Artemis missions. Another advantage of the Moon is its low inclination to the ecliptic, which maintains the Sun's apparent altitude inside a reduced angular range. For this reason, Ultraviolet solar radiation can be collected through a simplified Sun's tracking collector or even a static collector and used to disinfect the recycled air. Fluid-dynamic and optical simulations have been performed to support the proposed idea. The expected inactivation rates for some airborne pathogens, either common or found on the International Space Station, are reported and compared with the proposed device efficiency. The results show that it is possible to use Ultraviolet solar radiation directly for air disinfection inside the lunar outposts and deliver a healthy living environment to the astronauts.

Design of optical cavity for air sanification through ultraviolet germicidal irradiation.

The transmission of airborne pathogens represents a major threat to worldwide public health. Ultraviolet light irradiation can contribute to the sanification of air to reduce the pathogen transmission. We have designed a compact filter for airborne pathogen inactivation by means of UVC LED sources, whose effective irradiance is enhanced thanks to high reflective surfaces. We used ray-tracing and computational fluid dynamic simulations to model the device and to maximize the performance inside the filter volume. Simulations also show the inhibition of SARS-Cov-2 in the case of high air fluxes. This study demonstrates that current available LED technology is effective for air sanification purposes.

Rheological properties, biocompatibility and in vivo performance of new hydrogel-based bone fillers.

Three different heterologous substitutes for bone regeneration, manufactured with equine-derived cortical powder (CP), cancellous chips (CC) and demineralized bone matrix granules (DBM), were compared in in vitro and in vivo settings. We tested: a commercially available bone paste (Osteoplant-Activagen™, consisting of aqueous collagenous carrier, CP, DBM; named A); a second-generation injectable paste (20 kDa polyethylene glycol/hydroxypropyl-methyl cellulose-based hydrogel, CP, DBM; B); a pre-formed bone filler (400 kDa polyethylene oxide/hydroxypropyl-methyl cellulose-based hydrogel, CP, CC, DBM; C). Vitamin C acted as a visco-modulator during C and B ß-rays sterilization, modifying graft injectability. For each filler, we examined dissolution in culture medium, gene expression of the substitute-exposed osteogenically-induced human bone marrow stromal cells (hBMSC), and performance in a rabbit bone defect model. A dissolved after 1 h, while fragmentation of B peaked after 8 h. C remained unaltered for 2 days, but affected the microenvironmental pH, slowing the proliferation of exposed cells. B-exposed hBMSC overexpressed bone sialoprotein, osteocalcin and RUNX2. For all fillers histological results evidenced bridged lesion margins, marrow replenishment and bone-remodeling. However, B-treated lesions displayed a metachromatic type II collagen-rich matrix with prehypertrophic-like cells, matching the in vitro expression of cartilage-specific markers, and suggesting a possible application of B/C double-layer monolithic osteochondral plugs for full-thickness articular defects.

Differences in chemical composition and internal structure influence systemic host response to implants of biomaterials.

In reconstructive surgery, implantable devices are used to supply a missing function. In tissue engineering, biomaterials serve to guide and eventually deliver cells and/or molecules where a tissue regenerative response is needed. The host organism always reacts to implants of any biomaterial, in some instances even triggering a local cascade of events called the foreign body response (FBR), whose mechanisms are well defined. What has yet to be completely unraveled are the biomarkers systemically mirroring the FBR and the regeneration processes, which would be helpful for assessing the therapeutic efficacy of the bioscaffold. Our goal was to identify a biomarker fingerprint of the systemic reaction of host response to bioscaffold implants. Different biomaterials chosen for their osteoconductive properties, including collagen, hydroxyapatite, in foam or granules, and poly-ε-caprolactone, were implanted in immunocompetent mice. We analyzed serum concentrations of cells and cytokines involved in the inflammatory/immune response, and the histological features of grafts. Within two weeks after implantation, a wave of proinflammatory cytokines was flowing in the blood stream and the concentration of blood cells changed, revealing specific patterns depending on the chemistry and structure of the implanted biomaterials. Cells secreting pro-inflammatory, chemoactractant, and pro-angiogenic cytokines required for the early events in tissue repair were locally recruited because of the presence of a bioscaffold.

Highly emissive nanostructured thin films of organic host-guests for energy conversion.

All-organic nanostructured host-guest systems, based on dyes inserted in the nanochannels of perhydrotriphenylene (PHTP) and deoxycholic acid (DCA), show enhanced fluorescence properties with quantum yields even higher than those of the dyes in solution, thanks to the high concentration of emissive molecules with controlled spatial and geometrical organization that prevents aggregation quenching. Both host molecules crystallize, growing with the long axis oriented along the direction of the nanochannels where the linear-chain dyes are inserted, to yield crystals emitting well-polarized light. For the DCA-based host-guests, homogeneous thin films suitable for several applications are obtained. Colour emission in such films can be tuned by co-inclusion of two or three dyes due to resonant energy-transfer processes. We show that films obtained by low-cost techniques, such as solution casting and spin-coating, convert UV light into visible light with an efficiency much higher than that of the standard polymeric blends.

Enhanced lipid peroxidation in synoviocytes from patients with osteoarthritis.

OBJECTIVE: To evaluate the degree of lipid peroxidation of synoviocytes from patients with rheumatoid arthritis (RA), osteoarthitis (OA), and controls and to look at the production of nitric oxide (NO) and its involvement in this process. METHODS: Human synoviocytes were isolated from synovial tissues from patients with RA, OA, and from healthy controls. Cells were maintained in culture for up to 3 culture passages. Lipid peroxidation, verified by the production of malonaldehyde (MDA) and 4-hydroxy-2(E)-nonenal (4-HNE), was determined by colorimetric assay. NO was evaluated by estimating the stable NO metabolite nitrite by the Griess method in the supernatants of unstimulated and interleukin (IL)-1beta and tumor necrosis factor (TNF)-a stimulated cells. RESULTS: Increased levels of lipid peroxidation were observed for OA-derived synoviocytes compared to RA and controls. The cells in each experimental group produced low amounts of NO both in basal and in stimulated conditions. CONCLUSION: In OA, synovial cells underwent a lipid peroxidation process that did not occur in synoviocytes from RA or controls even in the absence of a detectable production of the reactive nitrogen intermediate NO. We can postulate that this peroxidation process might be due to the action of NO secreted by chondrocytes that are known to produce higher levels of this radical in OA compared to RA.

Cathepsin B as a soluble marker to monitor the phenotypic stability of engineered cartilage.

The clinical need for improved human autologous chondrocyte transplantation has motivated the use of different biomaterials, which are aimed at fixing the cells in the defect area and permit their proliferation and differentiation. The maintenance of the original phenotype by isolated chondrocytes grown in vitro is an important requisite for their use in repairing damaged articular cartilage. The methods to verify the expression of cartilage-specific molecules usually involve destructive procedures to recover the cells from the scaffolds for tests. The aim of our study was to find a soluble marker able to attest the occurrence of a differentiation process by chondrocytes grown onto a biomaterial used for cell transplantation. We turned our attention to cathepsin B which is known to be abnormally synthesized in de-differentiated chondrocytes and scarcely produced in the differentiated ones. The production of cathepsin B by human articular chondrocytes expanded in vitro and then grown onto a hyaluronan-based polymer derivative (Hyaff-11) three-dimensional scaffold was evaluated with a specific enzyme-immunoassay at different experimental times together with the expression of mRNA by real-time PCR. We showed that cathepsin B, which is abundantly produced by chondrocytes grown in a monolayer culture, decreases significantly after the cells are seeded onto the scaffold, giving further evidence of a re-differentiation process. This result suggests cathepsin B a practical soluble marker to evaluate the "good" quality of transplantable constructs.

Evidence for redifferentiation of human chondrocytes grown on a hyaluronan-based biomaterial (HYAff 11): molecular, immunohistochemical and ultrastructural analysis.

Association of biomaterials with autologous cells can provide a new generation of implantable devices for cartilage repair. Such scaffolds should provide a preformed three-dimensional shape and prevent cells from escaping into the articular cavity. Furthermore, these constructs should have sufficient mechanical strength to facilitate handling in a clinical setting and stimulate the uniform spreading of cells and their phenotype redifferentiation. The aim of this study was to verify the ability of HYAFF 11, a recently developed hyaluronic-acid-based biodegradable polymer, to support the growth of human chondrocytes and to maintain their original phenotype. This capability was assessed by the evaluation of collagen types I, II and aggrecan mRNA expression. Immunohistochemical analyses were also performed to evaluate collagen types I, II and proteoglycans synthesis. A field emission in lens scanning microscopy was utilized to verify the interactions between the cells and the biomaterial. Our data indicate that human chondrocytes seeded on HYAFF 11 express and produce collagen type II and aggrecan and downregulate the production of collagen type I. These results provide an in vitro demonstration for the therapeutic potential of HYAFF 11 as a delivery vehicle in a tissue-engineered approach towards the repair of articular cartilage defects.