Optimized Rhodamine B labeled mesoporous silica nanoparticles as fluorescent scaffolds for the immobilization of photosensitizers: a theranostic platform for optical imaging and photodynamic therapy

Theoretical study on the photophysical properties of thiophene-fused-type BODIPY series molecules in fluorescence imaging and photodynamic therapy

As a class of photosensitizers (PSs) with dual functions of photodynamic therapy (PDT) and fluorescence imaging, the relationship between the structure and dual-function of thiophene-fused-type BODIPY dyes has not been studied in depth before. We found that the thiophene-fused-type BODIPY triplet photosensitizer is produced according to the energy level matching rule and the introduction of the thiophene ring significantly reduces the energy gap ΔEST between singlet and triplet states, as revealed by our investigation of the excited state structures and energies of thieno-fused BODIPY dyes. At the same time, a tiny ΔEST also results in a greatly enhanced intersystem crossing (ISC) rate, kISC. The kISC value of MeO-BODIPY, having the highest singlet oxygen quantum yield (ΦΔ), is the largest. Substitution with a strong electron donor N,N-dimethylaminophenyl (DMA) leads to the vertical configuration in the T1 state. The small ΔE (0.0029 eV) between the HOMO and HOMO-1 triggers the photo induced electron transfer (PET) of inhibiting ISC and fluorescence. When thieno-fused BODIPYs react with pyrrole, the increase of π-conjugation and smaller ΔEHOMO-LUMO explain the redshift in emission wavelength of thieno-pyrrole-fused BODIPY. The more planar configuration of the S1 state and the stronger oscillator intensity reflect a higher fluorescence quantum yield (ΦF). The extension of π-conjugation can cause molecules to transition to higher-level singlet excited states (Sn states, n ≥ 1) after absorbing energy and reduce the energy level of the excited state, resulting in multiple channels and favoring 1O2 production for thieno-pyrrole-fused BODIPYs with electron-withdrawing groups at the para-position of the phenyl groups. Due to ΔES0-T1 < 0.980 eV, the substitution of electron-donating groups cannot produce 1O2. In this work, we have revealed the mechanism of ISC and the fluorescence emission process in the thiophene-fused-type BODIPY dye, which has provided a theoretical foundation and guidance for the future design of BODIPY-based heavy-atom-free PSs for molecular applications in PDT.

Characterization of TEMPO-Oxidized Cellulose Nanofiber From Biowaste and Its Influence on Molecular Behavior of Fluorescent Rhodamine B Dye in Aqueous Suspensions

Cellulose nanofiber (CNFs) obtained through TEMPO oxidation was structurally characterized using FT-IR (Fourier Transformed Infrared) and SEM (Scanning Electron Microscopy) spectroscopy. The molecular aggregation and spectroscopic properties of Rhodamine B (Rh-B) in CNFs suspension were investigated using molecular absorption and steady-state fluorescence spectroscopy techniques. The interaction between CNFs particles in the aqueous suspension and the cationic dye compound was examined in comparison to its behavior in deionized water. This interaction led to significant changes in the spectral features of Rh-B, resulting in an increase in the presence of H-dimer and H-aggregate in CNFs suspension. The H-type aggregates of Rh-B in CNFs suspensions were defined by the observation of a blue-shifted absorption band compared to that of the monomer. Even at diluted dye concentrations, the formation of Rh-B's H-aggregate was observed in CNFs suspension. The pronounced aggregation in suspensions originated from the strong interaction between negatively charged carboxylate ions and the dye. The aggregation behavior was discussed with deconvoluted absorption spectra. Fluorescence spectroscopy studies revealed a significant reduction in the fluorescence intensity of the dye in CNFs suspension due to H-aggregates. Furthermore, the presence of H-aggregates in the suspensions caused a decrease in the quantum yield of Rh-B compared to that in deionized water.

Recent advances in the role of Yes-associated protein in dermatosis

BACKGROUND

Dermatosis is a general term for diseases of the skin and skin appendages including scleroderma, psoriasis, bullous disease, atopic dermatitis, basal cell carcinoma, squamous cell carcinoma, and melanoma. These diseases affect millions of individuals globally and are a serious public health concern. However, the pathogenesis of skin diseases is not fully understood, and treatments are not optimal. Yes-associated protein (YAP) is a transcriptional coactivator that plays a role in the regulation of gene transcription and signal transduction.

AIMS

To study the role of Yes-associated protein in skin diseases.

MATERIALS AND METHODS

The present review summarizes recent advances in our understanding of the role of YAP in skin diseases, current treatments that target YAP, and potential avenues for novel therapies.

RESULTS

Abnormal YAP expression has been implicated in occurrence and development of dermatosis. YAP regulates the cell homeostasis, proliferation, differentiation, apoptosis, angiopoiesis, and epithelial-to-mesenchymal transition, among other processes. As well as, it serves as a potential target in many biological processes for treating dermatosis.

CONCLUSIONS

The effects of YAP on the skin are complex and require multidimensional investigational approaches. YAP functions as an oncoprotein that can promote the occurrence and development of cancer, but there is currently limited information on the therapeutic potential of YAP inhibition for cancer treatment. Additional studies are also needed to clarify the role of YAP in the development and maturation of dermal fibroblasts; skin barrier function, homeostasis, aging, and melanin production; and dermatosis.

Noninvasive, continuous fluorescence monitoring of bilirubin photodegradation

Nowadays phototherapy is widely used for treatment of various diseases. However, efficient application of phototherapy requires an understanding of light interactions with main endogenous chromophores (e.g., hemoglobin, bilirubin, and water) in tissue. In particular, bilirubin is the target chromophore in the treatment of neonatal jaundice, which is the most common disease affecting up to 80% of preterm infants. The most frequently recommended treatment technique for this disease is phototherapy with blue light in combination with conventional drug therapy. To follow threshold total serum bilirubin (TSB) concentration guidelines, it is essential to estimate TSB concentration accurately. The gold standard biochemical analysis is invasive and bulky. Moreover, noninvasive methods do not provide sufficient reproducibility and accuracy. In this research, the fluorescence sensing of bilirubin with human serum albumin complexes was studied. The fluorescence time course during light irradiation (central wavelength: 467 nm and power density: 12.13 mW cm^-2) was demonstrated to depend on the initial concentration. Specifically, for the bilirubin concentration C = 18.65 μM, an insignificant fluorescence signal increase was observed during the first 30 minutes of light irradiation, while for bilirubin concentration C = 373 μM, the fluorescence signal did not reach maximum during 2.5 hours of light irradiation. Thus, fluorescence sensing might show increased accuracy when used with other noninvasive bilirubin sensing methods.

Mesoporous silica nanoparticles incorporated with Ir(III) complexes: From photophysics to photodynamic therapy

Organically modified mesoporous silica nanoparticles (MSNs) containing Ir complexes (Ir1, Ir2 and Ir3) were successfully synthesized. These Ir-entrapped MCM41-COOH nanoparticles have shown relevant photophysical characteristics including high efficiency in the photoproduction and delivery of singlet oxygen (¹O₂), which is particularly promising for photodynamic therapy (PDT) applications. In vitro tests have evidenced that complex@MCM41-COOH are able to reduce cell proliferation after 10 min of blue-light irradiation in Hep-G2 liver cancer cells.

Red Upconverter Nanocrystals Functionalized with Verteporfin for Photodynamic Therapy Triggered by Upconversion

Upconversion (UC) nanoparticles characterized by red upconversion emission, particularly interesting for biological applications, have been prepared and subsequently modified by the covalent anchoring of Verteporfin (Ver), an FDA approved photosensitizer (PS) which usually exerts its photodynamic activity upon excitation with red light. ZrO2 was chosen as the platform where Yb3+ and Er3+ were inserted as the sensitizer and activator ions, respectively. Careful control of the doping ratio, along with a detailed physico-chemical characterization, was carried out. Upon functionalization with a silica shell to covalently anchor the photosensitizer, a theranostic nanoparticle was obtained whose architecture, thanks to a favorable energy level match and a uniform distribution of the PS, allowed us to trigger the photodynamic activity of Ver by upconversion, thus paving the way to the use of Photodynamic Therapy (PDT) in deep tissues, thanks to the higher penetrating power of NIR light.

Mesoporous Silica Nanoparticles Functionalized with Amino Groups for Biomedical Applications

The synthesis and characterization of amino-functionalized mesoporous silica nanoparticles are presented following two different synthetic methods: co-condensation and post-synthesis grafting of 3-aminopropyltriethoxysilane. The amino groups' distribution on the mesoporous silica nanoparticles was evaluated considering the aggregation state of a grafted photosensitizer (Verteporfin) by using spectroscopic techniques. The homogeneous distribution of amino groups within the silica network is a key factor to avoid aggregation during further organic functionalization and to optimize the performance of functionalized silica nanoparticles in biomedical applications. In addition, the formation of a protein corona on the external surface of both bare and amino-functionalized mesoporous silica was also investigated by adsorbing Bovine Serum Albumin (BSA) as a model protein. The adsorption of BSA was found to be favorable, reducing the aggregation phenomena for both bare and amino-modified nanoparticles. Nevertheless, the dispersant effect of BSA was much more evident in the case of amino-modified nanoparticles, which reached monodispersion after adsorption of the protein, thus suggesting that amino-modified nanoparticles can benefit from protein corona formation for preventing severe aggregation in biological media.

Functionalization of Photosensitized Silica Nanoparticles for Advanced Photodynamic Therapy of Cancer

BODIPY dyes have recently attracted attention as potential photosensitizers. In this work, commercial and novel photosensitizers (PSs) based on BODIPY chromophores (haloBODIPYs and orthogonal dimers strategically designed with intense bands in the blue, green or red region of the visible spectra and high singlet oxygen production) were covalently linked to mesoporous silica nanoparticles (MSNs) further functionalized with PEG and folic acid (FA). MSNs approximately 50 nm in size with different functional groups were synthesized to allow multiple alternatives of PS-PEG-FA decoration of their external surface. Different combinations varying the type of PS (commercial Rose Bengal, Thionine and Chlorine e6 or custom-made BODIPY-based), the linkage design, and the length of PEG are detailed. All the nanosystems were physicochemically characterized (morphology, diameter, size distribution and PS loaded amount) and photophysically studied (absorption capacity, fluorescence efficiency, and singlet oxygen production) in suspension. For the most promising PS-PEG-FA silica nanoplatforms, the biocompatibility in dark conditions and the phototoxicity under suitable irradiation wavelengths (blue, green, or red) at regulated light doses (10-15 J/cm2) were compared with PSs free in solution in HeLa cells in vitro.

Graphene Oxide Theranostic Effect: Conjugation of Photothermal and Photodynamic Therapies Based on an in vivo Demonstration

INTRODUCTION

Cancer is the second leading cause of death globally and is responsible, where about 1 in 6 deaths in the world. Therefore, there is a need to develop effective antitumor agents that are targeted only to the specific site of the tumor to improve the efficiency of cancer diagnosis and treatment and, consequently, limit the unwanted systemic side effects currently obtained by the use of chemotherapeutic agents. In this context, due to its unique physical and chemical properties of graphene oxide (GO), it has attracted interest in biomedicine for cancer therapy.

METHODS

In this study, we report the in vivo application of nanocomposites based on Graphene Oxide (nc-GO) with surface modified with PEG-folic acid, Rhodamine B and Indocyanine Green. In addition to displaying red fluorescence spectra Rhodamine B as the fluorescent label), in vivo experiments were performed using nc-GO to apply Photodynamic Therapy (PDT) and Photothermal Therapy (PTT) in the treatment of Ehrlich tumors in mice using NIR light (808 nm 1.8 W/cm2).

RESULTS

This study based on fluorescence images was performed in the tumor in order to obtain the highest concentration of nc-GO in the tumor as a function of time (time after intraperitoneal injection). The time obtained was used for the efficient treatment of the tumor by PDT/PTT.

DISCUSSION

The current study shows an example of successful using nc-GO nanocomposites as a theranostic nanomedicine to perform simultaneously in vivo fluorescence diagnostic as well as combined PDT-PTT effects for cancer treatments.

Porous Silica-Based Organic-Inorganic Hybrid Catalysts: A Review

Hybrid organic-inorganic catalysts have been extensively investigated by several research groups in the last decades, as they allow combining the structural robust-ness of inorganic solids with the versatility of organic chemistry. Within the field of hybrid catalysts, synthetic strategies based on silica are among the most exploitable, due to the convenience of sol-gel chemistry, to the array of silyl-derivative precursors that can be synthesized and to the number of post-synthetic functionalization strategies available, amongst others. This review proposes to highlight these advantages, firstly describing the most common synthetic tools and the chemistry behind sol-gel syntheses of hybrid catalysts, then presenting exemplificative studies involving mono- and multi-functional silica-based hybrid catalysts featuring different types of active sites (acid, base, redox). Materials obtained through different approaches are described and their properties, as well as their catalytic performances, are compared. The general scope of this review is to gather useful information for those approaching the synthesis of organic-inorganic hybrid materials, while providing an overview on the state-of-the art in the synthesis of such materials and highlighting their capacities.

Functionalized Fluorescent Silica Nanoparticles for Bioimaging of Cancer Cells

Functionalized fluorescent silica nanoparticles were designed and synthesized to selectively target cancer cells for bioimaging analysis. The synthesis method and characterization of functionalized fluorescent silica nanoparticles (50-60 nm), as well as internalization and subcellular localization in HeLa cells is reported here. The dye, rhodamine 101 (R101) was physically embedded during the sol-gel synthesis. The dye loading was optimized by varying the synthesis conditions (temperature and dye concentration added to the gel) and by the use of different organotriethoxysilanes as a second silica precursor. Additionally, R101, was also covalently bound to the functionalized external surface of the silica nanoparticles. The quantum yields of the dye-doped silica nanoparticles range from 0.25 to 0.50 and demonstrated an enhanced brightness of 230-260 fold respect to the free dye in solution. The shell of the nanoparticles was further decorated with PEG of 2000 Da and folic acid (FA) to ensure good stability in water and to enhance selectivity to cancer cells, respectively. In vitro assays with HeLa cells showed that fluorescent nanoparticles were internalized by cells accumulating exclusively into lysosomes. Quantitative analysis showed a significantly higher accumulation of FA functionalized fluorescent silica nanoparticles compared to nanoparticles without FA, proving that the former may represent good candidates for targeting cancer cells.

Toxicity and mechanism of mesoporous silica nanoparticles in eyes

The study on the safety of nanomaterials in eyes is still in its early stages. In this study, we put our focus on the effect of one important nanoparticle feature - large surface area - to assess eye safety. To this end, mesoporous silica nanoparticles (MSiNPs) were for the first time employed as a model to evaluate their toxicity in eyes. The porosity of the MSiNPs endows them with a large surface area and the ability to attach to surrounding chemical or biological molecules, further enhancing their surface reactivity and toxic effects. Therefore, to better mimic MSiNP exposure in real environments, we also introduced other hazardous substances such as silver ions (Ag+) to the system and then investigated their synergistic nanotoxicity. Our results showed that the exposure to MSiNPs-Ag+ and even Ag+ at a safe dose, resulted in more significant toxicity than the MSiNPs alone, as evidenced from cell viability, apoptosis, reactive oxygen species (ROS) production, and DNA damage experiments. RNA-Sequencing analysis revealed that the mRNA surveillance signalling pathway plays a unique role in regulating MSiNPs-Ag+-induced cytotoxicity. Besides this, severe corneal damage and dry eye were observed in rat models upon exposure to MSiNPs-Ag+ compared to MSiNPs. Most importantly, we also proposed a protein corona-based therapy to treat MSiNP-induced corneal disease, where the corneal damage could be rescued by fetal bovine serum (FBS) treatment.

Tantalum oxide nanoparticles as versatile contrast agents for X-ray computed tomography

Here, we describe the synthesis, characterization and in vitro and in vivo performance of a series of tantalum oxide (TaOx) based nanoparticles (NPs) for computed tomography (CT). Five distinct versions of 9-12 nm diameter silane coated TaOx nanocrystals (NCs) were fabricated by a sol-gel method with varying degrees of hydrophilicity and with or without fluorescence, with the highest reported Ta content to date (78%). Highly hydrophilic NCs were left bare and were evaluated in vivo in mice for micro-CT of full body vasculature, where following intravenous injection, TaOx NCs demonstrate high vascular CT contrast, circulation in blood for ∼3 h, and eventual accumulation in RES organs; and following injection locally in the mammary gland, where the full ductal tree structure can be clearly delineated. Partially hydrophilic NCs were encapsulated within mesoporous silica nanoparticles (MSNPs; TaOx@MSNPs) and hydrophobic NCs were encapsulated within poly(lactic-co-glycolic acid) (PLGA; TaOx@PLGA) NPs, serving as potential CT-imagable drug delivery vehicles. Bolus intramuscular injections of TaOx@PLGA NPs and TaOx@MSNPs to mimic the accumulation of NPs at a tumor site produce high signal enhancement in mice. In vitro studies on bare NCs and formulated NPs demonstrate high cytocompatibility and low dissolution of TaOx. This work solidifies that TaOx-based NPs are versatile contrast agents for CT.

The construction of a multifunctional metal–organic framework for targeting tumors and bioimaging

A simple one-pot process has been developed for the synthesis of multifunctional MOFs for targeting tumors and bioimaging.

Verteporfin-loaded mesoporous silica nanoparticles inhibit mouse melanoma proliferation in vitro and in vivo

Melanoma is one of the most lethal tumors among the skin cancers, arising from complex genetic mutations in melanocyte. Melanoma microenvironment is very heterogeneous, showing complex vascular networks and immunogenicity, as well as induced acquired resistance to treatments by upregulation of multidrug resistance (MDR) mechanisms. Different studies have showed that Photodynamic Therapy (PDT) could be considered a new potential approach for melanoma treatment. PDT combines a light with a specific wavelength and a photosensitizer: when these two elements interact reactive oxygen species (ROS) are generated leading to tumor cell destruction. In this study verteporfin (Ver), a second-generation photosensitizer, has been conjugated with mesoporous silica nanoparticles (MSNs): the resulting Ver-MSNs are an efficient nanoplatforms used to enhance cargo capacity and cellular uptake. Our in vitro and in vivo studies investigated whether Ver-MSNs were able to reduce or inhibit melanoma growth. In vitro experiments performed using B16F10 mouse melanoma cells showed that Ver-MSNs stimulated by red light (693 nm) significantly decreased in vitro cells proliferation in a range of concentration between 0.1 μg/ml to 10 μg/ml. When Ver-MSNs (5 μg/ml in glycerol) were topically administrated to melanoma tumor mass developed in mice and stimulated by red light for four times in 16 days, they were able to reduce the tumor mass of 50.2 ± 6,6% compared to the untreated (only glycerol) mice. In the light of this information, PDT performed using Ver-MSNs could be considered a new promising and potential approach to treat melanoma.

Excitation of triplet states of hypericin in water mediated by hydrotropic cromolyn sodium salt

Hypericin (Hyp) is a hydrophobic pigment found in plants of the genus Hypericum which exhibits low levels of solubility in water. This work shows that the solubility of Hyp can be significantly increased through the addition of cromolyn disodium salt (DSCG). Performed studies using UV-VIS absorption and fluorescence spectroscopies demonstrate that Hyp remains in a predominantly biologically photodynamic active monomeric form in the presence of DSCG at concentrations ranging from 4.6×10^-3 to 1.2×10^-1mol·L^-1. The low association constant between Hyp and DSCG (K_a=71.7±2M^-1), and the polarity value of 0.3 determined for Hyp in a DSCG-water solution, lead to a suggestion that the monomerization of Hyp in aqueous solution can be explained as a result of the hydrotropic effect of DSCG. This hydrotropic effect is most likely a result of interactions between two relative rigid aromatic rings of DSCG and a delocalized charge on the surface of the Hyp molecule. The triplet-triplet (T-T) electronic transition observed in is Hyp in the presence of DSCG suggests a possible production of reactive oxygen species once Hyp is irradiated with visible light in a DSCG aqueous solution.

Adapting BODIPYs to singlet oxygen production on silica nanoparticles

A modified Stöber method is used to synthesize spherical core-shell silica nanoparticles (NPs) with an external surface functionalized by amino groups and with an average size around 50 nm. Fluorescent dyes and photosensitizers of singlet oxygen were fixed, either separately or conjointly, respectively in the core or in the shell. Rhodamines were encapsulated in the core with relatively high fluorescence quantum yields (Φ_fl ≥ 0.3), allowing fluorescence tracking of the particles. Various photosensitizers of singlet oxygen (PS) were covalenty coupled to the shell, allowing singlet oxygen production. The stability of NP suspensions strongly deteriorated upon grafting the PS, affecting their apparent singlet oxygen quantum yields. Agglomeration of NPs depends both on the type and on the amount of grafted photosensitizer. New, lab-made, halogenated 4,4-difluoro-4-bora-3a,4a-diaza-s-indacenes (BODIPY) grafted to the NPs achieved higher singlet oxygen quantum yields (Φ_Δ ∼ 0.35-0.40) than Rose Bengal (RB) grafted NPs (Φ_Δ ∼ 0.10-0.27). Finally, we combined both fluorescence and PS functions in the same NP, namely a rhodamine in the silica core and a BODIPY or RB grafted in the shell, achieving the performance Φ_fl ∼ 0.10-0.20, Φ_Δ ∼ 0.16-0.25 with a single excitation wavelength. Thus, proper choice of the dyes, of their concentrations inside and on the NPs and the grafting method enables fine-tuning of singlet oxygen production and fluorescence emission.

Host–guest luminescent materials based on highly emissive species loaded into versatile sol–gel hosts

By mostly focusing on the findings of our group, this concise review provides insights into the development of promising new host–guest optical materials based on sol–gel assemblies of versatile hosts and highly luminescent guests.

Mesoporous silica nanoparticles incorporating squaraine-based photosensitizers: a combined experimental and computational approach

A combined experimental–computational approach allowed a correlation of the homogeneity of the dispersion of squaraine dyes within mesoporous silica nanoparticles with their photosensitizer activity.

One-pot synthesis of hierarchical-pore metal–organic frameworks for drug delivery and fluorescent imaging

A one-pot process has been developed for the synthesis of hierarchical-pore metal–organic frameworks, aimed at loading large and small drug molecules simultaneously.

Photothermal therapeutic application of gold nanorods-porphyrin-trastuzumab complexes in HER2-positive breast cancer

Gold nanorods are effective photothermal agents in diagnosis and treatment of cancer due to their specific near-infrared laser absorption. However, tumor photothermal therapy by nanorods alone is lack of targeting. Here, we described a novel nanocomplex made up of gold nanorods, porphyrin, and trastuzumab, called TGNs and investigated the TGN-mediated photothermal therapy as a potential alternative treatment of targeting HER2-positive breast cancers. By conjugating trastuzumab and porphyrin to the surface of gold nanorods, we have increased the targeting specificity and amplified the detecting effectiveness at the same time. TGN-mediated photothermal ablation by near-infrared laser led to a selective destruction of HER2-positive cancer cells and significantly inhibited tumor growth in mouse models bearing HER2 over-expressed breast cancer xenograft with less toxicity. Moreover, TGNs provided better therapeutic efficacy in comparison with the conventional molecule targeted therapy. Our current data suggest a highly promising future of TGNs for its therapeutic application in trastuzumab-resistant breast cancers.

Verteporfin based silica nanoparticle for in vitro selective inhibition of human highly invasive melanoma cell proliferation

Photodinamic therapy (PDT) has gained an increasing interest as a new tool to treat skin cancers such as melanoma. This clinical approach take advantage from the combination of a photosensitizer and a specific light wavelength able to induce singlet oxygen production. Mesoporous silica nanoparticles (MSNs) have been widely investigated as drug nanocarriers as their structure and morphology could be customized to produce suitable nanoplatforms enabling high cargo capacity. In the present study MSNs were successfully conjugated with the second generation photosensitizer verteporfin and the resulting nanoplatform (Ver-MSNs) was tested in an in vitro PDT model as a potential tool for melanoma treatment. Ver-MSNs based PDT did not affect cell proliferation of neither a normal human keratinocyte cell line (HaCaT) or a low mestastatic melanoma cell line (A375P). On the other hand Ver-MSNs based PDT deeply affect the highly invasive SK-MEL-28 melanoma cell line behavior, as testified by the strong reduction in cell proliferation along with the dramatic change in cellular morphology, through a nanoparticle internalization dependent mechanism. In fact, experiments performed in the presence of endocytosis inhibitors (chlorpromazine and amiloride) resulted in an attenuation of Ver-MSNs based PDT induced cell death, along with a recover in cellular morphology. MSN doped with verteporfin could thus represent a promising and useful tool for PDT treatment of highly invasive melanoma.