A NIR light-triggered drug delivery system using core-shell gold nanostars-mesoporous silica nanoparticles based on multiphoton absorption photo-dissociation of 2-nitrobenzyl PEG.

Gold nanostars coated with a mesoporous silica shell and functionalized with poly(ethylene glycol) containing photolabile 2-nitrobenzyl moieties are able to release doxorubicin after NIR light irradiation at low power irradiance via a multiphoton absorption photo-dissociation process.

Janus Gold Nanostars-Mesoporous Silica Nanoparticles for NIR-Light-Triggered Drug Delivery.

Janus gold nanostar-mesoporous silica nanoparticle (AuNSt-MSNP) nanodevices able to release an entrapped payload upon irradiation with near infrared (NIR) light were prepared and characterized. The AuNSt surface was functionalized with a thiolated photolabile molecule (5), whereas the mesoporous silica face was loaded with a model drug (doxorubicin) and capped with proton-responsive benzimidazole-ß-cyclodextrin supramolecular gatekeepers (N 1). Upon irradiation with NIR-light, the photolabile compound 5 photodissociated, resulting in the formation of succinic acid, which induced the opening of the gatekeeper and cargo delivery. In the overall mechanism, the gold surface acts as a photochemical transducer capable of transforming the NIR-light input into a chemical messenger (succinic acid) that opens the supramolecular nanovalve. The prepared hybrid nanoparticles were non-cytotoxic to HeLa cells, until they were irradiated with a NIR laser, which led to intracellular doxorubicin release and hyperthermia. This induced a remarkable reduction in HeLa cells viability.

Gold Nanostars Coated with Mesoporous Silica Are Effective and Nontoxic Photothermal Agents Capable of Gate Keeping and Laser-Induced Drug Release.

Herein, a novel drug photorelease system based on gold nanostars (AuNSts), coated with a mesoporous silica shell and capped with paraffin as thermosensitive molecular gate, is reported. Direct measurements of the surface temperature of a single gold nanostar irradiated using a tightly focused laser beam are performed via a heat-sensitive biological matrix. The surface temperature of a AuNSt increases by hundreds of degrees (°C) even at low laser powers. AuNSts coated with a mesoporous silica shell using a surfactant-templated synthesis are used as chemotherapeutic nanocarriers. Synthetic parameters are optimized to avoid AuNSt reshaping, and thus to obtain nanoparticles with suitable and stable plasmonic properties for near-infrared (NIR) laser-triggered cargo delivery. The mesoporous silica-coated nanostars are loaded with doxorubicin (Dox) and coated with octadecyltrimethoxysilane and the paraffin heneicosane. The paraffin molecules formed a hydrophobic layer that blocks the pores, impeding the release of the cargo. This hybrid nanosystem exhibits a well-defined photodelivery profile using NIR radiation, even at low power density, whereas the nonirradiated sample shows a negligible payload release. Dox-loaded nanoparticles displayed no cytotoxicity toward HeLa cells, until they are irradiated with 808 nm laser, provoking paraffin melting and drug release. Hence, these novel, functional, and biocompatible nanoparticles display adequate plasmonic properties for NIR-triggered drug photorelease applications.

Rapid Biosynthesis of Silver Nanoparticles Using Pepino (Solanum muricatum) Leaf Extract and Their Cytotoxicity on HeLa Cells.

Within nanotechnology, gold and silver nanostructures have unique physical, chemical, and electronic properties [1,2], which make them suitable for a number of applications. Moreover, biosynthetic methods are considered to be a safer alternative to conventional physicochemical procedures for both the environmental and biomedical applications, due to their eco-friendly nature and the avoidance of toxic chemicals in the synthesis. For this reason, employing bio routes in the synthesis of functionalized silver nanoparticles (FAgNP) have gained importance recently in this field. In the present study, we report the rapid synthesis of FAgNP through the extract of pepino (Solanum muricatum) leaves and employing microwave oven irradiation. The core-shell globular morphology and characterization of the different shaped and sized FAgNP, with a core of 20-50 nm of diameter is established using the UV-Visible spectroscopy (UV-vis), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and Zeta potential and dynamic light scanning (DLS) studies. Moreover, cytotoxic studies employing HeLa (human cervix carcinoma) cells were undertaken to understand FAgNP interactions with cells. HeLa cells showed significant dose dependent antiproliferative activity in the presence of FAgNP at relatively low concentrations. The calculated IC50 value was 37.5 µg/mL, similar to others obtained for FAgNPs against HeLa cells.

Synthesis and In†Vitro Evaluation of a Photosensitizer-BODIPY Derivative for Potential Photodynamic Therapy Applications.

A new photosensitizer (1) based on the 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) scaffold has been synthesized. 1 is water soluble and showed an intense absorption band at 490 nm (ɛ=77,600 cm(-1) m(-1)) and an emission at 514 nm. In vitro toxicity of 1 in the presence of light and in darkness has been studied with HeLa, HaCaT, MCF-7, and SCC-13 cell lines. Moreover, internalization studies of 1 in these cell lines were also performed. These results suggested that 1 is more toxic for SCC-13 and HeLa carcinoma cells than for the HaCaT non-cancerous immortal human keratinocytes. Toxicity upon light irradiation was due to the formation of singlet oxygen and reactive oxygen species (ROS). Cellular co-localization experiments revealed preferential localization of the dye in the endoplasmic reticulum.

Gated mesoporous silica nanoparticles for the controlled delivery of drugs in cancer cells.

In recent years, mesoporous silica nanoparticles (MSNs) have been used as effective supports for the development of controlled-release nanodevices that are able to act as multifunctional delivery platforms for the encapsulation of therapeutic agents, enhancing their bioavailability and overcoming common issues such as poor water solubility and poor stability of some drugs. In particular, redox-responsive delivery systems have attracted the attention of scientists because of the intracellular reductive environment related to a high concentration of glutathione (GSH). In this context, we describe herein the development of a GSH-responsive delivery system based on poly(ethylene glycol)- (PEG-) capped MSNs that are able to deliver safranin O and doxorubicin in a controlled manner. The results showed that the PEG-capped systems designed in this work can be maintained closed at low GSH concentrations, yet the cargo can be delivered when the concentration of GSH is increased. Moreover, the efficacy of the PEG-capped system in delivering the cytotoxic agent doxorubicin in cells was also demonstrated.