Next generation wound care technology capable of diagnosing wound parameters, promoting healthy cell growth and reducing pathogenic infections noninvasively would provide patients with an improved standard of care and an accelerated wound repair mechanism. Temperature is one of the indicating biomarkers specific to chronic wounds. This work reports a hybrid, multifunctional optical material platform -nanodiamond-silk membranes as bioinspired dressings capable of temperature sensing and wound healing. The hybrid structure was fabricated through electrospinning and formed 3D sub-micron fibrous membranes with high porosity. The silk fibres are capable of compensating for the lack of extracellular matrix at the wound site, supporting the wound healing process. The negatively charged nitrogen vacancy (NV -) color centres in nanodiamonds (NDs) exhibit optically detected magnetic resonance (ODMR) properties and act as fluorescent nanoscale thermometers, capable of sensing temperature variations associated to the presence of infection or inflammation in a wound, without physically removing the dressing. Our results show that the presence of NDs in the hybrid ND-silk membranes improve the thermal stability of silk fibres. The NVcolor centres in NDs embedded in silk fibres exhibit well-retained fluorescent and ODMR properties. Using the NVcentres as fluorescent nanoscale thermometers, we achieved temperature sensing at a range of temperatures, including the biologically relevant temperature window, on cellcultured ND-silk membranes. An enhancement in the temperature sensitivity of the NVcentres was observed for the hybrid materials. The hybrid membranes were further tested in vivo in a murine wound healing model and demonstrated biocompatibility and equivalent wound closure rates as the control wounds. Additionally, the hybrid ND-silk membranes showed selective antifouling and biocidal propensity toward Gram-negative Pseudomonas aeruginosa and Escherichia coli, while no effect was observed on Gram-positive Staphylococcus aureus.

The toxicity of manufactured nanoparticles varies greatly depending on the test species in consideration and estimates of toxicity may also be confounded by test media in which the organisms are cultured. For a more comprehensive toxicity evaluation, species at different trophic levels or with life strategies, tested in different media should be included. In this study, we examined the toxicity of tyrosine-coated silver nanonparticles (tyr-AgNP) to three Australian freshwater invertebrates: Hydra vulgaris, Daphnia carinata, and Paratya australiensis. Tyr-AgNPs were synthesized, characterized and their behavior was examined in different media used for acute toxicity tests. Additionally, the sensitivity of tested organisms to tyr-AgNPs was compared to ionic silver (Ag +). Based on the LC 50 values of both tyr-AgNPs and Ag + ions at different time points, D. carinata was found to be the most sensitive species followed by P. australiensis and H. vulgaris. NP stability studies revealed that tyr-AgNPs were least stable in hydra medium followed by daphnid and shrimp media. This study demonstrates that significant differences in NP toxicity to aquatic organisms exist and the test media and the life strategy of the species play a key role in these differences. Therefore, it is recommended that a multispecies approach is used in predictive risk assessment of NPs and to ensure protection of native species from possible toxic effects from NPs released into aquatic systems. Also recommended is to carefully investigate the fate and behavior of NPs in different media in assessing NP toxicity and emphasize the need to use native species in developing relevant regulatory frameworks.

A pyridyl functionalised tetraphenylethylene (Py-TPE) for ratiometric fluorescent detection of intracellular pH values is reported. The Py-TPE fluorescent probe can be used for H + sensing in organic solvents (CHCl 3 , DMF and MeOH) and the change in optical density through absorption, emission and naked eye detection was modulated. On addition of TFA, an aggregation-induced enhancement of emission with an increase in quantum yield of 0.11 to 0.63, due to an intramolecular charge transfer (ICT) process was observed. This process is reversed by addition of TEA resulting in a cycle that can be repeated several times.

Fluorescent nanoparticles (NPs) have been increasingly studied as contrast agents for better understanding of biological processes at the cellular and molecular level. However, their use as bioimaging tools is strongly dependent on their optical emission as well as their biocompatibility. This work reports the fabrication and characterization of silk fibroin (SF) coated magnesium oxide (MgO) nanospheres, containing oxygen, Cr3+ and V2+ related optical defects, as a nontoxic and biodegradable hybrid platform for bioimaging applications. The MgO-SF spheres demonstrated enhanced emission efficiency compared to noncoated MgO NPs. Furthermore, SF sphere coating was found to overcome agglomeration limitations of the MgO NPs. The hybrid nanospheres were investigated as an in vitro bioimaging tool by recording their cellular uptake, trajectories, and mobility in human skin keratinocytes cells (HaCaT), human glioma cells (U87MG) and breast cancer cells (MCF7). Enhanced cellular uptake and improved intracellular mobilities of MgO-SF spheres compared to MgO NPs was demonstrated in three different cell lines. Validated infrared and bright emission of MgO-SF NP indicate their prospects for in vivo imaging. The results identify the potential of the hybrid MgO-SF nanospheres for bioimaging. This study may also open new avenues to optimize drug delivery through biodegradable silk and provide noninvasive functional imaging feedback on the therapeutic processes through fluorescent MgO.

The rapid formation of the protein corona on to the nanoparticle (NP) surface is the key that confers biological identity to NPs and subsequently dictates their fate both in vitro and in vivo. Despite significant efforts, the inability to control the spontaneous interaction of serum proteins with the administered NPs remains a major constraint in clinical translation of nanomedicines. The ligands present on the NP surface offer promise in controlling their biological interactions; however, their influence on the NP–protein interaction is not well-understood. The current study investigates the potential of phytochemical-capped silver nanoparticles (AgNPs) toward allowing a control over NP interactions with the human serum albumin (HSA), the most abundant protein in the biological fluids. Specifically, we demonstrate the ability of curcumin (Cur) and epigallocatechin-3-gallate (EGCG) to independently act as reducing agents to produce phytochemical-capped AgNPs that show biologically desirable interactions with HSA. The key finding of our study is that the phytochemical-capped AgNPs initially interact with HSA more strongly compared to the citrate-stabilized AgNPs; however, the resultant NP–HSA complexes are less stable in the case of the former, which causes a lesser degree of changes in the protein conformation during interactions. Further, the choice of the phytochemical allows control over NP–HSA interactions, such that Cur- and EGCG-capped AgNPs interacted with HSA in a static versus dynamic manner, respectively. The diversity of the functional groups present in natural phytochemicals and their potential as in situ capping ligands during synthesis offer new opportunities in controlling the interactions of NPs with complex biological fluids, with implications in nanodiagnostics and nanomedicine.

Imaging of biological matter by using fluorescent nanoparticles (NPs) is becoming a widespread method for in vitro imaging. However, currently there is no fluorescent NP that satisfies all necessary criteria for short-term in vivo imaging: biocompatibility, biodegradability, photostability, suitable wavelengths of absorbance and fluorescence that differ from tissue auto-fluorescence, and near infrared (NIR) emission. In this paper, we report on the photoluminescent properties of magnesium oxide (MgO) NPs that meet all these criteria. The optical defects, attributed to vanadium and chromium ion substitutional defects, emitting in the NIR, are observed at room temperature in NPs of commercial and in-house ball-milled MgO nanoparticles, respectively. As such, the NPs have been successfully integrated into cultured cells and photostable bright in vitro emission from NPs was recorded and analyzed. We expect that numerous biotechnological and medical applications will emerge as this nanomaterial satisfies all criteria for short-term in vivo imaging.

The use of silver nanoparticles (AgNPs) is growing exponentially, especially in consumer products due to their excellent antimicrobial properties. However, concerns are growing on their possible negative effects on environmental and human health. AgNPs from consumer products enter aquatic ecosystems where their physicochemical properties including surface functionalization are critical to their impact on aquatic organisms. The effects of AgNPs coated with three different ligands; tyrosine (T-AgNP), epigallocatechin gallate (E-AgNP) and curcumin (C-AgNP) and Ag + ions on the freshwater green alga Raphidocelis subcapitata were investigated. Stability tests of AgNPs revealed that the coating significantly affects the fate and behaviour of AgNPs. All types of AgNPs tested and ionic silver were found to be toxic to the alga and differential growth inhibition of algae were observed from differently coated AgNPs, with the 48 h EC 50 of C-AgNPs, T-AgNPs and E-AgNPs being 0.155, 0.163 and 0.243 mg L −1 , respectively, in comparison with 0.051 mg L −1 for Ag + ions. Associated Ag in the algae increased with increased concentrations of all AgNPs and Ag + ions and the toxicity positively correlated to the associated Ag content in algae. The antioxidant enzymes glutathione S-transferase and catalase were activated in algal cells by the AgNPs and Ag + ions, but a consistent difference in response was not identified with different concentrations of NPs. This study shows the effects of the surrounding environment and surface functionalization of AgNPs on algae highlighting the importance of considering them in environmental risk assessment of AgNPs.

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