Development of alginate-based film incorporated with anthocyanins of red cabbage and zinc oxide nanoparticles as freshness indicator for prawns.

The objective of this study was to develop pH-sensitive film indicators for intelligent food packaging by incorporating red cabbage anthocyanins (RCA) and zinc oxide nanoparticles (ZnO NPs) into an alginate (Alg) film, aiming to mitigate the risk of foodborne illnesses. The films were fabricated using a solvent-casting method and crosslinked with a calcium chloride (CaCl2) solution. Thorough evaluations of the films' physical, mechanical, and structural properties demonstrated significant improvements in elastic modulus and UV/vis light barrier characteristics, reduced water vapor permeability (WVP), and moisture content attributed to integrating RCA and ZnO NPs. The resulting film displayed discernible color changes when exposed to various pH buffer solutions and ammonia vapor, indicating heightened sensitivity to pH fluctuations due to the presence of ZnO NPs. Visual assessment using prawns as test specimens revealed a color shift from violet (indicating satisfactory condition) to blue-greenish (indicating spoilage), corroborated by colorimetric analysis. Moreover, the Alg/ZnO/RCA film exhibited antioxidant and antibacterial properties, demonstrated biodegradation activity, and showed no toxic effects on RSC96 cells, further underscoring its potential as an effective freshness indicator for food products.

The Role of a Confined Space on the Reactivity and Emission Properties of Copper(I) Clusters.

Metal clusters have gained a lot of interest for their remarkable photoluminescence and catalytic properties. However, a major drawback of such materials is their poor stability in air and humidity conditions. Herein we describe a versatile method to synthesize luminescent Cu(I) clusters inside the pores of zeolites, using a sublimation technique with the help of high vacuum and high temperature. The porous materials play an essential role as a protecting media against the undesirable and easy oxidation of Cu(I). The obtained clusters show fascinating luminescence properties, and their reactivity can be triggered by insertion in the pores of organic monodentate ligands such as pyridine or triphenylphosphine. The coordinating ligands can lead to the formation of Cu(I) complexes with completely different emission properties. In the case of pyridine, the final compound was characterized and identified as a cubane-like structure. A thermochromism effect is also observed, featuring, for instance, a hypsochromic effect for a phosphine derivative at 77K. The stability of the encapsulated systems in zeolites is rather enthralling: they are stable and emissive even after several months in the air.

Cellular lasers for cell imaging and biosensing.

The possibility to produce laser action involving biomaterials, in particular (single) biological cells, has fostered the development of cellular lasers as a novel approach in biophotonics. In this respect, cells that are engineered to carry gain medium (e.g., fluorescent dyes or proteins) are placed inside an optical cavity (i.e., typically a sandwich of highly reflective mirrors), allowing the generation of stimulated emission upon sufficient optical pumping. In another scenario, micron-sized optical resonators supporting whispering-gallery mode (WGM) or semiconductor-based laser probes can be internalized by the cells and support light amplification. This review summarizes the recent advances in the fields of biolasers and cellular lasers, and most importantly, highlights their potential applications in the fields of in vitro and in vivo cell imaging and analysis. They include biosensing (e.g., in vitro detection of sodium chloride (NaCl) concentration), cancer cell imaging, laser-emission-based microscope, cell tracking, cell distinction study, and tissue contraction monitoring in zebrafish. Lastly, several fundamental issues in developing cellular lasers including laser probe fabrication, biocompatibility of the system, and alteration of local refractive index of optical cavities due to protein absorption or probe aggregation are described. Cellular lasers are foreseen as a promising tool to study numerous biological and biophysical phenomena. STATEMENT OF SIGNIFICANCE: Biolasers are generation of laser involving biological materials. Biomaterials, including single cells, can be engineered to incorporate laser probes or fluorescent proteins or fluorophores, and the resulting light emission can be coupled to optical resonator, allowing generation of cellular laser emission upon optical pumping. Unlike fluorescence, this stimulated emission is very sensitive and is capable of detecting small alterations in the optical property of the cells and their environment. In this review, recent development and applications of cellular lasers in the fields of in vitro and in vivo cell imaging, cell tracking, biosensing, and cell/tissue analysis are highlighted. Several challenges in developing cellular lasers including probe fabrication and biocompatibility as well as alteration of cellular environment are explained.

Fluorescent Nanozeolite Receptors for the Highly Selective and Sensitive Detection of Neurotransmitters in Water and Biofluids.

The design and preparation of synthetic binders (SBs) applicable for small biomolecule sensing in aqueous media remains very challenging. SBs designed by the lock-and-key principle can be selective for their target analyte but usually show an insufficient binding strength in water. In contrast, SBs based on symmetric macrocycles with a hydrophobic cavity can display high binding affinities but generally suffer from indiscriminate binding of many analytes. Herein, a completely new and modular receptor design strategy based on microporous hybrid materials is presented yielding zeolite-based artificial receptors (ZARs) which reversibly bind the neurotransmitters serotonin and dopamine with unprecedented affinity and selectivity even in saline biofluids. ZARs are thought to uniquely exploit both the non-classical hydrophobic effect and direct non-covalent recognition motifs, which is supported by in-depth photophysical, and calorimetric experiments combined with full atomistic modeling. ZARs are thermally and chemically robust and can be readily prepared at gram scales. Their applicability for the label-free monitoring of important enzymatic reactions, for (two-photon) fluorescence imaging, and for high-throughput diagnostics in biofluids is demonstrated. This study showcases that artificial receptor based on microporous hybrid materials can overcome standing limitations of synthetic chemosensors, paving the way towards personalized diagnostics and metabolomics.

Surface functionalization of zeolite-based drug delivery systems enhances their antitumoral activity in vivo.

Zeolites have attractive features making them suitable carriers for drug delivery systems (DDS). As such, we loaded the anticancer drug 5-fluorouracil (5-FU), into two different zeolite structures, faujasite (NaY) and Linde Type L (LTL), to obtain different DDS. The prepared DDS were tested in vitro using breast cancer, colorectal carcinoma, and melanoma cell lines and in vivo using the chick embryo chorioallantoic membrane model (CAM). Both assays showed the best results for the Hs578T breast cancer cells, with a higher potentiation for 5-FU encapsulated in the zeolite LTL. To unveil the endocytic mechanisms involved in the internalization of the zeolite nanoparticles, endocytosis was inhibited pharmacologically in breast cancer and epithelial mammary human cells. The results suggest that a caveolin-mediated process was responsible for the internalized zeolite nanoparticles. Aiming to boost the DDS efficacy, the disc-shaped zeolite LTL outer surface was functionalized using amino (NH2) or carboxylic acid (COOH) groups and coated with poly-l-lysine (PLL). Positively functionalized surface LTL nanoparticles revealed to be non-toxic to human cells and, importantly, their internalization was faster and led to a higher tumor reduction in vivo. Overall, our results provide further insights into the mechanisms of interaction between zeolite-based DDS and cancer cells, and pave the way for future studies aiming to improve DDS anticancer activity.

Design, synthesis and antiamoebic activity of dysprosium-based nanoparticles using contact lenses as carriers against Acanthamoeba sp.

PURPOSE: Contact lenses have direct contact with the corneal surface and can induce sight-threatening infection of the cornea known as Acanthamoeba keratitis. The objective of this study was to evaluate the dysprosium-based nanoparticles (Dy-based NPs), namely Fe3 O4 -PEG-Dy2 O3 nanocomposites and Dy(OH)3 nanorods, as an active component against Acanthamoeba sp., as well as the possibility of their loading onto contact lenses as the drug administering vehicle to treat Acanthamoeba keratitis (AK). METHODS: The Dy-based NPs were synthesized, and they were loaded onto commercial contact lenses. The loading content of the NPs and their release kinetics was determined based on the absorbance of their colloidal solution before and after soaking the contact lenses. The cytotoxicity of the NPs was evaluated, and the IC50 values of their antiamoebic activity against Acanthamoeba sp. were determined by MTT colorimetric assay, followed by observation on the morphological changes by using light microscopy. The mechanism of action of the Dy-based NPs against Acanthamoeba sp. was evaluated by DNA laddering assays. RESULTS: The loading efficiencies of the Dy-based NPs onto the contact lens were in the range of 30.6-36.1% with respect to their initial concentration (0.5 mg ml-1 ). The Dy NPs were released with the flux approximately 5.5-11 µg cm-2  hr-1 , and the release was completed within 10 hr. The emission of the NPs consistently showed a peak at 575 nm due to Dy3+ ion, offering the possible monitoring and tracking of the NPs. The SEM images indicated the NPs are aggregated on the surface of the contact lenses. The DNA ladder assay suggested that the cells underwent DNA fragmentation, and the cell death was due most probably to necrosis, rather than apoptosis. The cytotoxicity assay of Acanthamoeba sp. suggested that Fe3 O4 -PEG, Fe3 O4 -PEG-Dy2 O3 , Dy(NO3 )3 .6H2 O and Dy(OH)3 NPs have an antiamoebic activity with the IC50 value being 4.5, 5.0, 9.5 and 22.5 µg ml-1 , respectively. CONCLUSIONS: Overall findings in this study suggested that the Dy-based NPs can be considered as active antiamoebic agents and possess the potential as drugs against Acanthamoeba sp. The NPs could be loaded onto the contact lenses; thus, they can be potentially utilized to treat Acanthamoeba keratitis (AK).

Luminescence of Amphiphilic PtII Complexes Controlled by Confinement.

The formation of hybrid silica-based systems to study the effect of the confinement on the emission properties of self-assembled platinum(II) complexes is reported. The complexes behave as surfactants since they possess a hydrophobic moiety and, on the ancillary ligand, a relatively long hydrophilic chain terminated with a positively charged group. The compounds, soluble in water, self-assemble, even at very low concentration, in supramolecular structures which display an orange luminescence. The properties of the assemblies have been studied in detail and in order to stabilize these supramolecular architectures and to enhance their emission properties hybrid silica porous nanoparticles have been prepared. In particular the PtII complexes have been employed as co-surfactant for the template formation of mesoporous silica nanoparticles (MSNs) using a sol gel synthesis. Interestingly, upon encapsulation in the silica pores, the platinum aggregates exhibit an emission profile similar in energy to the complexes assembled in solution, but the photoluminescence quantum yields of the hybrid systems are significantly higher (up to 45 %), and the excited state lifetimes much longer than those recorded in solution. Such enhancement of the photophysical properties together with the possibility to process the hybrid silica nanomaterials can pave the way to new type of emitters.

Internalization studies on zeolite nanoparticles using human cells.

Zeolites are crystalline porous materials with a regular framework which have non-toxic effects on a variety of human cell lines and have been explored for cell imaging and drug delivery. Understanding the interaction between zeolite nanoparticles and cells is imperative for improving their potentialities, since the process of internalization of these particles is still poorly understood. In this study, the intracellular trafficking and internalization kinetics of zeolite L into breast cancer cells and normal epithelial mammary cells were analysed using scanning electron microscopy (SEM), confocal microscopy and transmission electron microscopy (TEM). We also studied the involvement of endocytic pathways using two pharmacological inhibitors, chlorpromazine and dynasore. Zeolite nanoparticles were taken up by both cell types and the cellular uptake was fast, and started immediately after 5 min of incubation. Interestingly, the uptake was dependent on the cell type since in breast cancer cells it was faster and more efficient, with a higher number of nanoparticles being internalized by cancer cells over time, compared to that in the epithelial mammary cells. TEM results showed that the internalized nanoparticles were mainly localized in the cell vacuoles. The data obtained upon using endocytic pharmacological inhibitors suggest that the zeolite L uptake is mediated by caveolin.

Proton-driven coordination-induced spin state switch (PD-CISSS) of iron(ii) complexes.

Here we report the completely reversible spin state switch of the naturally diamagnetic tris(bipyridine)iron(ii) complex and the spin crossover complex bis(2,6-bis(1H-pyrazol-3-yl)pyridine)iron(ii) by the variation of the pH followed by 1H-NMR, UV-Vis spectroscopy, and magnetic and relaxivity measurements in solution and as composite materials encapsulated in a zeolite matrix.

Fast Targeting and Cancer Cell Uptake of Luminescent Antibody-Nanozeolite Bioconjugates.

Understanding the targeted cellular uptake of nanomaterials is an essential step to engineer and program functional and effective biomedical devices. In this respect, the targeting and ultrafast uptake of zeolite nanocrystals functionalized with Cetuximab antibodies (Ctxb) by cells overexpressing the epidermal growth factor receptor are described here. Biochemical assays show that the cellular uptake of the bioconjugate in the targeted cancer cells already begins 15 min after incubation, at a rate around tenfold faster than that observed in the negative control cells. These findings further show the role of Ctxb exposed at the surfaces of the zeolite nanocrystals in mediating the targeted and rapid cellular uptake. By using temperature and pharmacological inhibitors as modulators of the internalization pathways, the results univocally suggest a dissipative uptake mechanism of these nanomaterials, which seems to occur using different internalization pathways, according to the targeting properties of these nanocrystals. Owing to the ultrafast uptake process, harmless for the cell viability, these results further pave the way for the design of novel theranostic tools based on nanozeolites.

Nanocomposite Hydrogels as Platform for Cells Growth, Proliferation, and Chemotaxis.

The challenge of mimicking the extracellular matrix with artificial scaffolds that are able to reduce immunoresponse is still unmet. Recent findings have shown that mesenchymal stem cells (MSC) infiltrating into the implanted scaffold have effects on the implant integration by improving the healing process. Toward this aim, a novel polyamidoamine-based nanocomposite hydrogel is synthesized, cross-linked with porous nanomaterials (i.e., mesoporous silica nanoparticles), able to release chemokine proteins. A comprehensive viscoelasticity study confirms that the hydrogel provides optimal structural support for MSC infiltration and proliferation. The efficiency of this hydrogel, containing the chemoattractant stromal cell-derived factor 1α (SDF-1α), in promoting MSC migration in vitro is demonstrated. Finally, subcutaneous implantation of SDF-1α-releasing hydrogels in mice results in a modulation of the inflammatory reaction. Overall, the proposed SDF-1α-nanocomposite hydrogel proves to have potential for applications in tissue engineering.

Light-enhanced liquid-phase exfoliation and current photoswitching in graphene-azobenzene composites.

Multifunctional materials can be engineered by combining multiple chemical components, each conferring a well-defined function to the ensemble. Graphene is at the centre of an ever-growing research effort due to its combination of unique properties. Here we show that the large conformational change associated with the trans-cis photochemical isomerization of alkyl-substituted azobenzenes can be used to improve the efficiency of liquid-phase exfoliation of graphite, with the photochromic molecules acting as dispersion-stabilizing agents. We also demonstrate reversible photo-modulated current in two-terminal devices based on graphene-azobenzene composites. We assign this tuneable electrical characteristics to the intercalation of the azobenzene between adjacent graphene layers and the resulting increase in the interlayer distance on (photo)switching from the linear trans-form to the bulky cis-form of the photochromes. These findings pave the way to the development of new optically controlled memories for light-assisted programming and high-sensitive photosensors.

Reactive Microcontact Printing of DNA Probes on (DMA-NAS-MAPS) Copolymer-Coated Substrates for Efficient Hybridization Platforms.

High-performing hybridization platforms fabricated by reactive microcontact printing of DNA probes are presented. Multishaped PDMS molds are used to covalently bind oligonucleotides over a functional copolymer (DMA-NAS-MAPS) surface. Printed structures with minimum width of about 1.5 µm, spaced by 10 µm, are demonstrated, with edge corrugation lower than 300 nm. The quantification of the immobilized surface probes via fluorescence imaging gives a remarkable concentration of 3.3 × 10(3) oligonucleotides/µm(2), almost totally active when used as probes in DNA-DNA hybridization assays. Indeed, fluorescence and atomic force microscopy show a 95% efficiency in target binding and uniform DNA hybridization over printed areas.

Modular Graphene-Based 3D Covalent Networks: Functional Architectures for Energy Applications.

The development of ordered graphene-based materials combining high stability, large surface areas, ability to act as absorbent of relevant chemical species, and solution processability is of significance for energy applications. A poorly explored approach relies on the controlled nanostructuration of graphene into robust and highly ordered 3D networks as a route to further leverage the exceptional properties of this unique material. Here, a simple yet effective and scalable one-step method is reported to prepare graphene-based 3D covalent networks (G3DCNs) with tunable interlayer distance via controlled polymerization of benzidines with graphene oxide at different reaction temperatures under catalyst- and template-free conditions. The reduced form of G3DCNs is used as electrodes in supercapacitors; it reveals a high specific capacitance of 156 F g(-1) at a current density of 1 A g(-1) in a two-electrode configuration and 460 F g(-1) at a current density of 0.5 A g(-1) in a three-electrode configuration, combined with an excellent cycling stability over 5000 cycles. The present study will promote the quantitative understanding of structure-property relationship, for the controlled fabrication of 3D graphene-based multifunctional materials.

Breakable Hybrid Organosilica Nanocapsules for Protein Delivery.

The direct delivery of specific proteins to live cells promises a tremendous impact for biological and medical applications, from therapeutics to genetic engineering. However, the process mostly involves tedious techniques and often requires extensive alteration of the protein itself. Herein we report a straightforward approach to encapsulate native proteins by using breakable organosilica matrices that disintegrate upon exposure to a chemical stimulus. The biomolecule-containing capsules were tested for the intracellular delivery of highly cytotoxic proteins into C6 glioma cells. We demonstrate that the shell is broken, the release of the active proteins occurs, and therefore our hybrid architecture is a promising strategy to deliver fragile biomacromolecules into living organisms.

Combined Delivery of Temozolomide and Anti-miR221 PNA Using Mesoporous Silica Nanoparticles Induces Apoptosis in Resistant Glioma Cells.

Mesoporous silica nanoparticles (MSNPs), 100 nm in size, incorporating a Cy5 fluorophore within the silica framework, are synthesized and loaded with the anti-cancer drug temozolomide (TMZ), used in the treatment of gliomas. The surface of the particles is then decorated, using electrostatic interactions, with a polyarginine-peptide nucleic acid (R8-PNA) conjugate targeting the miR221 microRNA. The multi-functional nanosystem thus obtained is rapidly internalized into glioma C6 or T98G cells. The anti-miR activity of the PNA is retained, as confirmed by reverse transcription polymerase chain reaction (RT-PCR) measurements and induction of apoptosis is observed in temozolomide-resistant cell lines. The TMZ-loaded MSNPs show an enhanced pro-apoptotic effect, and the combined effect of TMZ and R8-PNA in the MSNPs shows the most effective induction of apoptosis (70.9% of apoptotic cells) thus far achieved in the temozolomide-resistant T98G cell line.

Towards eumelanin@zeolite hybrids: pore-size-controlled 5,6-dihydroxyindole polymerization.

5,6-Dihydroxyindole (1) and its N-methyl derivative (2), key eumelanin building blocks, were inserted into zeolite L by sublimation at 175 °C for 5 days. At a 10 mg/300 mg indole/zeolite ratio, the resulting hybrids displayed a stable deep red coloration. CP/MAS (13)C NMR and UV/Vis spectroscopy of the red species suggested the generation and accommodation of quinonoid biindole derivative(s) within the void space of the acidic zeolite channels. Removal of the zeolite matrix by treatment with HF gave a stable species that could be separated by HPLC and characterized by mass spectrometry as an oxygenated biindole derivative (or a mixture of isomers), suggesting addition of water to the original dimer and subsequent re-oxidation. The characterization was corroborated by optimized molecular geometries and simulated UV spectra with density functional calculations. Loading 1 or 2 into the larger pores of SBA-15 type mesoporous silica resulted in black eumelanin-type polymers, confirming channel size dependence over the polymerization process.