Terminal sterilization of bone allografts by gamma radiation is often essential prior to their clinical use to minimize the risk of infection and disease transmission. While gamma radiation has efficacy superior to other sterilization methods it also impairs the material properties of bone allografts, which may result in premature clinical failure of the allograft. The mechanisms by which gamma radiation sterilization damages bone tissue are not well known although there is evidence that the damage is induced via free radical attack on the collagen. In the light of the existing literature, it was hypothesized that gamma radiation induced biochemical damage to bone's collagen that can be reduced by scavenging for the free radicals generated during the ionizing radiation. It was also hypothesized that this lessening of the extent of biochemical degradation of collagen will be accompanied by alleviation in the extent of biomechanical impairment secondary to gamma radiation sterilization. Standardized tensile test specimens machined from human femoral cortical bone and specimens were assigned to four treatment groups: control, scavenger treated-control, irradiated and scavenger treated-irradiated. Thiourea was selected as the free radical scavenger and it was applied in aqueous form at the concentration of 1.5 M. Monotonic and cyclic mechanical tests were conducted to evaluate the mechanical performance of the treatment groups and the biochemical integrity of collagen molecules were assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.The native mechanical properties of bone tissue did not change by thiourea treatment only. The effect of thiourea treatment on mechanical properties of irradiated specimens were such that the post-yield energy, the fracture energy and the fatigue life of thiourea treated-irradiated treatment group were 1.9-fold, 3.3-fold and 4.7-fold greater than those of the irradiated treatment group, respectively. However, the mechanical function of thiourea treated and irradiated specimens was not to the level of unirradiated controls. The damage occurred through the cleavage of the collagen backbone as revealed by SDS PAGE analysis. Irradiated specimens did not exhibit a noteworthy amount of intact a-chains whereas those irradiated in the presence of thiourea demonstrated intact a-chains. Results demonstrated that free radical damage is an important pathway of damage, caused by cleaving the collagen backbone. Blocking the activity of free radicals using the scavenger thiourea reduces the extent of damage to collagen, helping to maintain the mechanical strength of sterilized tissue. Therefore, free radical scavenger thiourea has the potential to improve the functional life-time of the allograft component following transplantation.

Gossypol (Gsp), a natural toxin concentrated in cottonseeds, poses great risks to the safe consumption of cottonseed products, which are used extensively throughout the food industry. In this work, we report the first luminescence “turn-on” sensors for Gsp using near-infrared emitting lanthanide (Ln3+) materials, including Ln3+ MOFs and Ln3+ salts. We first demonstrate that the Yb3+ photoluminescence of a Yb3+ MOF, Yb-NH2-TPDC, can be employed to selectively detect Gsp with a limit of detection of 25 μg/mL via a “turn-on” response from a completely nonemissive state in the absence of Gsp. The recyclability and stability of Yb-NH2-TPDC in the presence of Gsp was demonstrated by fluorescence spectroscopy and PXRD analysis, respectively. A variety of background substances present in practical samples that would require Gsp sensing, such as refined cottonseed oil, palmitic acid, linoleic acid, and α-tocopherol, did not interfere with the Yb3+ photoluminescence signal. We further identified that the “turn-on” of Yb-NH2-TPDC photoluminescence was due to the “antenna effect” of Gsp, as evidenced by spectroscopic studies and supported by computational analysis. This is the first report that Gsp can effectively sensitize Yb3+ photoluminescence. Leveraging this sensing mechanism, we demonstrate facile, highly sensitive, fast-response detection of Gsp using YbCl3·6H2O and NdCl3·6H2O solutions. Overall, we show for the first time that Ln3+-based materials are promising luminescent sensors for Gsp detection. We envision that the reported sensing approach will be applicable to the detection of a wide variety of aromatic molecules using Ln3+ compounds including MOFs, complexes, and salts.

Multicomponent reactions (MCRs) can be used to introduce different functionalities into highly stable covalent organic frameworks (COFs). In this work, the irreversible three-component Doebner reaction is utilized to synthesize four chemically stable quinoline-4-carboxylic acid DMCR-COFs (DMCR-1−3 and DMCR-1NH) equipped with an acid−base bifunctionality. These DMCR-COFs show superior photocatalytic H 2 O 2 evolution (one of the most important industrial oxidants) compared to the imine COF analogue (Imine-1). This is achieved with sacrificial oxidants but also in pure water and under an oxygen or air atmosphere. Furthermore, the DMCR-COFs show high photostability, durability, and recyclability. MCR-COFs thus provide a viable materials' platform for solar to chemical energy conversion.

A triazine-based dual-functionalized covalent organic framework was developed and its application for the molecular decoding of VOCs, separation of Bz/Cy and selective and ultrafast detection of TNP in water was investigated.

On the basis of the strategic design of a triazine-based dicarboxylate ligand with two primary amino groups and one secondary amino group, an amine-functionalized autofluorescent and polar three-dimensional metal organic framework (MOF) {[Cd(ATAIA)]·4HO} (1), where HATAIA = 5-((4,6-diamino-1,3,5-triazin-2-yl)amino)isophthalic acid, has been synthesized under two different solvothermal conditions and structurally characterized. Single-crystal X-ray analysis reveals that 1 crystallizes in the orthorhombic polar space group Fdd2, where each ATAIA ligand acts as a linear linker to connect four Cd(II) centers, resulting in the formation of a three-dimensional framework with a repeat of a double helical metal chain. It has been further characterized by elemental analysis, UV-vis and Fourier transform infrared spectroscopy, and thermogravimetric analysis. Its bulk phase purity and stability in aqueous acid and base solutions are confirmed by powder X-ray diffraction. Both field emission scanning electron microscopy and high resolution transmission electron microscopy images of 1 reflect the formation of microflowers by self-assembly of nanopetals. With the dehydrated framework of 1, sorption studies of different gases (N, H, and CO) as well as polar and nonpolar solvents, such as water, benzene (Bz), and cyclohexane (Cy), have been performed. The CO sorption isotherm depicts type I isotherm at 298 and 273 K and type IV isotherm at 195 K. Furthermore, with an uptake of 129.2 cm g (25.62 wt %) at 195 K, sorption of CO is selective over N (77 K) and H (77 K) because of the strong adsorbate-adsorbent interaction as clearly evident from an isosteric heat of adsorption ( Q) at zero coverage of 37.5 kJ mol, which is exceptionally higher than that of other functionalized MOFs. Using the ideal adsorption solution theory calculation for a CO/N (15:85) mixture, selectivity values are found to be 54.08 (298 K) and 46.96 (273 K) at 100 kPa. For a major application, activated 1 has been utilized for selective and ultrafast detection of 2,4,6-trinitrophenol (TNP) in water with a limit of 0.94 nM (0.2 ppb), which supersedes any previous reported value. Excellent recyclability and stability of 1 for sensing experiments have been established. Time-resolved fluorescence studies and density functional theory calculations have been used to establish its mechanism of action. Furthermore, a prototype experiment for the real-time sensing of TNP in the vapor phase by fluorescence microscopy provides an easy colorimetric monitoring.