pH sensitive chitosan-mesoporous silica nanoparticles for targeted delivery of a ruthenium complex with enhanced anticancer effects

A pH-responsive bi-MIL-88B MOF coated with folic acid-conjugated chitosan as a promising nanocarrier for targeted drug delivery of 5-Fluorouracil

Cancer has remained one of the leading causes of death worldwide, with a lack of effective treatment. The intrinsic shortcomings of conventional therapeutics regarding tumor specificity and non-specific toxicity prompt us to look for alternative therapeutics to mitigate these limitations. In this regard, we developed multifunctional bimetallic (FeCo) bi-MIL-88B-FC MOFs modified with folic acid-conjugated chitosan (FC) as drug delivery systems (DDS) for targeted delivery of 5-Fluorouracil (5-FU). The bi-MIL-88B nanocarriers were characterized through various techniques, including powder X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray, thermogravimetric analysis, and Fourier transform infrared spectroscopy. Interestingly, 5-FU@bi-MIL-88B-FC showed slower release of 5-FU due to a gated effect phenomenon endowed by FC surface coating compared to un-modified 5-FU@bi-MIL-88B. The pH-responsive drug release was observed, with 58% of the loaded 5-FU released in cancer cells mimicking pH (5.2) compared to only 24.9% released under physiological pH (5.4). The in vitro cytotoxicity and cellular internalization experiments revealed the superiority of 5-FU@bi-MIL-88B-FC as a highly potent targeted DDS against folate receptor (FR) positive SW480 cancer cells. Moreover, due to the presence of Fe and Co in the structure, bi-MIL-88B exhibited peroxidase-like activity for chemodynamic therapy. Based on the results, 5-FU@bi-MIL-88B-FC could serve as promising candidate for smart DDS by sustained drug release and selective targeting.

Half-sandwich Ru(II) N-heterocyclic carbene complexes in anticancer drug design

The ruthenium arene fragment is a rich source for the design of anticancer drugs; in this design, the co-ligand is a critical factor for obtaining effective anticancer complexes. In comparison with other types of ligands, N-heterocyclic carbenes (NHCs) have been less explored, despite the versatility in structural modifications and the marked stabilization of metal ions, being these characteristics important for the design of metal drugs. However, notable advances have been made in the development of NHC Ruthenium arene as anticancer agents. These advances include high antitumor activities, proven both in in vitro and in in vivo models and, in some cases, with marked selectivity against tumorigenic cells. The versatility of the structure has played a fundamental role, since they have allowed a selective interaction with their molecular targets through, for example, bio-conjugation with known anticancer molecules. For this reason, the structure-activity relationship of the imidazole, benzimidazole, and abnormal NHC ruthenium (II) η6-arene complexes have been studied. Taking into account this study, several synthetic aspects are provided to contribute to the next generations of this kind of complexes. Moreover, in recent years nanotechnology has provided innovative nanomedicines, where half-sandwich Ruthenium(II) complexes are paving their way. In this review, the recent developments in nanomaterials functionalized with Ruthenium complexes for targeted drug delivery to tumors will also be highlighted.

New Nanostructured Materials Based on Mesoporous Silica Loaded with Ru(II)/Ru(III) Complexes with Anticancer and Antimicrobial Properties

A new series of nanostructured materials was obtained by functionalization of SBA-15 mesoporous silica with Ru(II) and Ru(III) complexes bearing Schiff base ligands derived from salicylaldehyde and various amines (1,2-diaminocyclohexane, 1,2-phenylenediamine, ethylenediamine, 1,3-diamino-2-propanol, N,N-dimethylethylenediamine, 2-aminomethyl-pyridine, and 2-(2-aminoethyl)-pyridine). The incorporation of ruthenium complexes into the porous structure of SBA-15 and the structural, morphological, and textural features of the resulting nanostructured materials were investigated by FTIR, XPS, TG/DTA, zeta potential, SEM, and N₂ physisorption. The ruthenium complex-loaded SBA-15 silica samples were tested against A549 lung tumor cells and MRC-5 normal lung fibroblasts. A dose-dependent effect was observed, with the highest antitumoral efficiency being recorded for the material containing [Ru(Salen)(PPh₃)Cl] (50%/90% decrease in the A549 cells' viability at a concentration of 70 μg/mL/200 μg/mL after 24 h incubation). The other hybrid materials have also shown good cytotoxicity against cancer cells, depending on the ligand included in the ruthenium complex. The antibacterial assay revealed an inhibitory effect for all samples, the most active being those containing [Ru(Salen)(PPh₃)Cl], [Ru(Saldiam)(PPh₃)Cl], and [Ru(Salaepy)(PPh₃)Cl], especially against Staphylococcus aureus and Enterococcus faecalis Gram-positive strains. In conclusion, these nanostructured hybrid materials could represent valuable tools for the development of multi-pharmacologically active compounds with antiproliferative, antibacterial, and antibiofilm activity.

Biopolymer-Based Nanosystems for siRNA Drug Delivery to Solid Tumors including Breast Cancer

Nanobiopolymers such as chitosan, gelatin, hyaluronic acid, polyglutamic acid, lipids, peptides, exosomes, etc., delivery systems have prospects to help overwhelmed physiological difficulties allied with the delivery of siRNA drugs to solid tumors, including breast cancer cells. Nanobiopolymers have favorable stimuli-responsive properties and therefore can be utilized to improve siRNA delivery platforms to undruggable MDR metastatic cancer cells. These biopolymeric siRNA drugs can shield drugs from pH degradation, extracellular trafficking, and nontargeted binding sites and are consequently suitable for drug internalization in a controlled-release fashion. In this review, the utilization of numerous biopolymeric compounds such as siRNA drug delivery systems for MDR solid tumors, including breast cancers, will be discussed.

Co-delivery of STAT3 siRNA and methotrexate in breast cancer cells

Co-delivery of anticancer drugs and biologics can provide synergetic effects and outperform single delivery therapies. Here, a nanoparticle (NP) system for co-delivery of methotrexate (MTX) and STAT3 siRNA has been developed and tested in vitro. Mesoporous silica nanoparticles (MSNs) were functionalized with chitosan (ch) by covalent grafting mediated by aminopropyl triethoxysilane (APTES) via glutaraldehyde as the linker. Co-delivery of MTX and STAT3 siRNA to MCF7 cells was demonstrated in cells by flow cytometric analysis and confocal laser scanning fluorescence microscopy for use in breast cancer treatment. MTX either competitively inhibits the dihydrofolate reductase (DHFR) receptor or suppresses the STAT3 metabolic pathway. STAT3 protein plays an essential role in cell division, proliferation and survival. Reduction of the protein by both MTX and STAT3 siRNA, achieved by chMSNs, significantly decreased the viability of breast cancer cells compared to single treatments alone. Cellular uptake of modified NPs was increased over time when additional free MTX was added implicating the DHFR receptor in uptake. In addition, protein corona compositions coated the NPs outer surface, were different between the NPs with and without drug potentially modulating cellular uptake. This study is the first report on co-delivery of MTX and STAT3 siRNA by chitosan modified MSNs.

Ruthenium-based antitumor drugs and delivery systems from monotherapy to combination therapy

Ruthenium complex is an important compound group for antitumor drug research and development. NAMI-A, KP1019, TLD1433 and other ruthenium complexes have entered clinical research. In recent years, the research on ruthenium antitumor drugs has not been limited to single chemotherapy drugs; other applications of ruthenium complexes have emerged such as in combination therapy. During the development of ruthenium complexes, drug delivery forms of ruthenium antitumor drugs have also evolved from single-molecule drugs to nanodrug delivery systems. The review summarizes the following aspects: (1) ruthenium complexes from monotherapy to combination therapy, including the development of single-molecule compounds, carrier nanomedicine, and self-assembly of carrier-free nanomedicine; (2) ruthenium complexes in the process of ADME in terms of absorption, distribution, metabolism and excretion; (3) the applications of ruthenium complexes in combination therapy, including photodynamic therapy (PDT), photothermal therapy (PTT), photoactivated chemotherapy (PACT), immunotherapy, and their combined application; (4) the future prospects of ruthenium-based antitumor drugs.

Engineering mesoporous silica nanoparticles for drug delivery: where are we after two decades?

The present review details a chronological description of the events that took place during the development of mesoporous materials, their different synthetic routes and their use as drug delivery systems. The outstanding textural properties of these materials quickly inspired their translation to the nanoscale dimension leading to mesoporous silica nanoparticles (MSNs). The different aspects of introducing pharmaceutical agents into the pores of these nanocarriers, together with their possible biodistribution and clearance routes, would be described here. The development of smart nanocarriers that are able to release a high local concentration of the therapeutic cargo on-demand after the application of certain stimuli would be reviewed here, together with their ability to deliver the therapeutic cargo to precise locations in the body. The huge progress in the design and development of MSNs for biomedical applications, including the potential treatment of different diseases, during the last 20 years will be collated here, together with the required work that still needs to be done to achieve the clinical translation of these materials. This review was conceived to stand out from past reports since it aims to tell the story of the development of mesoporous materials and their use as drug delivery systems by some of the story makers, who could be considered to be among the pioneers in this area.

Cancer-Targeted Chitosan-Biotin-Conjugated Mesoporous Silica Nanoparticles as Carriers of Zinc Complexes to Achieve Enhanced Chemotherapy In Vitro and In Vivo

Despite being the most common component of numerous metalloenzymes in the human body, zinc complexes are still under-rated as chemotherapeutic agents. Herein, the present study opens up a key route toward enhanced chemotherapy with the help of two Zn^II complexes (ZnMBC) synthesized alongside Mannich base ligands to upsurge biological potency. Further, well-established mesoporous silica nanoparticles (MSNs) have been chosen as carriers of the titled metallodrugs in order to achieve anticancer drug delivery. A pH-sensitive additive, namely, chitosan (CTS) conjugated with biotin is tagged to MSNs for the targeted release of core agents inside tumors selectively. In general, CTS blocks ZnMBC inside the mesopores of MSNs, and biotin acts as a targeting ligand to improve tumor-specific cellular uptake. CTS-biotin surface decoration significantly enhanced the cellular uptake of ZnMBC through endocytosis. A panel of four human cancer cell lines has revealed that ZnMBC (1/2)@MSNs-CTS-biotin nanoparticles (NPs) exhibits unprecedented enhanced cytotoxicity toward cancer cells with IC₅₀ values ranging from 6.5 to 28.8 μM through induction of apoptosis. NPs also possess great selectivity between normal and cancer cells despite this potency. Two-photon-excited in vitro imaging of normal (HEK) and cancer (HeLa) cells has been performed to confirm the biased drug delivery. Also, NP-induced apoptosis was found to be dependent on targeting DNA and ROS generation. Moreover, a lower range of LD₅₀ values (153.6-335.5 μM) were observed upon treatment zebrafish embryos with NPs in vivo. Because of the anatomical similarity to the human heart, the heart rate of NP-treated zebrafish has been analyzed in assessing the cardiac functions, which is in favor of the early clinical trials of ZnMBC (1/2)@MSNs-CTS-biotin candidates for their further evaluation as a chemotherapeutic and chemopreventive agent toward human cancers, especially adenocarcinoma.

Are smart delivery systems the solution to overcome the lack of selectivity of current metallodrugs in cancer therapy?

Chemotherapeutic metallodrugs such as cisplatin and its derivatives are among the most widely applied anticancer treatments worldwide. Nonetheless their clinical success, patients suffer from severe adverse effects while subjected to...

Biotinylated chitosan macromolecule based nanosystems: A review from chemical design to biological targets

World Health Organization estimates that 30-50% of cancers are preventable by healthy lifestyle choices, early detection and adequate therapy. When the conventional therapeutic strategies are still regulated by the lack of selectivity, multidrug resistance and severe toxic side effects, nanotechnology grants a new frontier for cancer management since it targets cancer cells and spares healthy tissues. This review highlights recent studies using biotin molecule combined with functional nanomaterials used in biomedical applications, with a particular attention on biotinylated chitosan-based nanosystems. Succinctly, this review focuses on five areas of recent advances in biotin engineering: (a) biotin features, (b) biotinylation approaches, (c) biotin functionalized chitosan based nanosystems for drug and gene delivery functions, (d) diagnostic and theranostic perspectives, and (e) author's inputs to the biotin-chitosan based tumour-targeting drug delivery structures. Precisely engineered biotinylated-chitosan macromolecules shaped into nanosystems are anticipated to emerge as next-generation platforms for treatment and molecular imaging modalities applications.

pH-Responsive Release of Ruthenium Metallotherapeutics from Mesoporous Silica-Based Nanocarriers

Ruthenium complexes are attracting interest in cancer treatment due to their potent cytotoxic activity. However, as their high toxicity may also affect healthy tissues, efficient and selective drug delivery systems to tumour tissues are needed. Our study focuses on the construction of such drug delivery systems for the delivery of cytotoxic Ru(II) complexes upon exposure to a weakly acidic environment of tumours. As nanocarriers, mesoporous silica nanoparticles (MSN) are utilized, whose surface is functionalized with two types of ligands, (2-thienylmethyl)hydrazine hydrochloride (H1) and (5,6-dimethylthieno[2,3-d]pyrimidin-4-yl)hydrazine (H2), which were attached to MSN through a pH-responsive hydrazone linkage. Further coordination to ruthenium(II) center yielded two types of nanomaterials MSN-H1[Ru] and MSN-H2[Ru]. Spectrophotometric measurements of the drug release kinetics at different pH (5.0, 6.0 and 7.4) confirm the enhanced release of Ru(II) complexes at lower pH values, which is further supported by inductively coupled plasma optical emission spectrometry (ICP-OES) measurements. Furthermore, the cytotoxicity effect of the released metallotherapeutics is evaluated in vitro on metastatic B16F1 melanoma cells and enhanced cancer cell-killing efficacy is demonstrated upon exposure of the nanomaterials to weakly acidic conditions. The obtained results showcase the promising capabilities of the designed MSN nanocarriers for the pH-responsive delivery of metallotherapeutics and targeted treatment of cancer.

Inorganic-inorganic nanohybrids for drug delivery, imaging and photo-therapy: recent developments and future scope

Advanced nanotechnology has been emerging rapidly in terms of novel hybrid nanomaterials that have found various applications in day-to-day life for the betterment of the public. Specifically, gold, iron, silica, hydroxy apatite, and layered double hydroxide based nanohybrids have shown tremendous progress in biomedical applications, including bio-imaging, therapeutic delivery and photothermal/dynamic therapy. Moreover, recent progress in up-conversion nanohybrid materials is also notable because they have excellent NIR imaging capability along with therapeutic benefits which would be useful for treating deep-rooted tumor tissues. Our present review highlights recent developments in inorganic-inorganic nanohybrids, and their applications in bio-imaging, drug delivery, and photo-therapy. In addition, their future scope is also discussed in detail.

Designing Mesoporous Silica Nanoparticles to Overcome Biological Barriers by Incorporating Targeting and Endosomal Escape

The several biological barriers that nanoparticles might encounter when administered to a patient constitute the major bottleneck of nanoparticle-mediated tumor drug delivery, preventing their successful translation into the clinic and reducing their therapeutic profile. In this work, mesoporous silica nanoparticles have been employed as a platform to engineer a versatile nanomedicine able to address such barriers, achieving (a) excessive premature drug release control, (b) accumulation in tumor tissues, (c) selective internalization in tumoral cells, and (d) endosomal escape. The nanoparticles have been decorated with a self-immolative redox-responsive linker to prevent excessive premature release, to which a versatile and polyvalent peptide that is able to recognize tumoral cells and induce the delivery of the nanoparticles to the cytoplasm via endosomal escape has been grafted. The excellent biological performance of the carrier has been demonstrated using 2D and 3D in vitro cell cultures and a tumor-bearing chicken embryo model, demonstrating in all cases high biocompatibility and cytotoxic effect, efficient endosomal escape and tumor penetration, and accumulation in tumors grown on the chorioallantoic membrane of chicken embryos.

Rhodium(i) N-heterocyclic carbene complexes: synthesis and cytotoxic properties

A series of benzimidazolium salts and their [RhCl(NHC)(COD)] complexes were synthesized. All compounds were screened for in vitro cytotoxic activities against a panel of human cancer cells (HT-29 colon, Ishikawa endometrial, U-87 glioblastoma) using the MTT assay for 48 h incubation time.

Mesoporous Silica Nanoparticles for Targeting Subcellular Organelles

Current chemotherapy treatments lack great selectivity towards tumoral cells, which leads to nonspecific drug distribution and subsequent side effects. In this regard, the use of nanoparticles able to encapsulate and release therapeutic agents has attracted growing attention. In this sense, mesoporous silica nanoparticles (MSNs) have been widely employed as drug carriers owing to their exquisite physico-chemical properties. Because MSNs present a surface full of silanol groups, they can be easily functionalized to endow the nanoparticles with many different functionalities, including the introduction of moieties with affinity for the cell membrane or relevant compartments within the cell, thus increasing the efficacy of the treatments. This review manuscript will provide the state-of-the-art on MSNs functionalized for targeting subcellular compartments, focusing on the cytoplasm, the mitochondria, and the nucleus.

Amino-Functionalized Mesoporous Silica Nanoparticle-Encapsulated Octahedral Organoruthenium Complex as an Efficient Platform for Combatting Cancer

In the process of synthesis of a new drug, as important as the drug itself is the formulation used, because the same compound can present a very different efficacy depending on how it is administered. In this work, we demonstrate how the antitumor capacity of a new octahedral organoruthenium complex, [Ru(ppy-CHO)(phen)₂][PF₆] is affected by its encapsulation in different types of mesoporous silica nanoparticles. The interactions between the Ru complex and the silica matrix and how these interactions are affected at two different pHs (7.4 and 5.4, mimicking physiological and endolysosomal acidic conditions, respectively) have been studied. The encapsulation has also been shown to affect the induction of apoptosis and necrosis and progression of the cell cycle compared to the free drug. The encapsulation of the Ru complex in nanoparticles functionalized with amino groups produced very high anticancer activity in cancer cells in vitro, especially against U87 glioblastoma cells, favoring cellular internalization and significantly increasing the anticancer capacity of the initial non-encapsulated Ru complex.

Influence of the Surface Functionalization on the Fate and Performance of Mesoporous Silica Nanoparticles

Mesoporous silica nanoparticles have been broadly applied as drug delivery systems owing to their exquisite features, such as excellent textural properties or biocompatibility. However, there are various biological barriers that prevent their proper translation into the clinic, including: (1) lack of selectivity toward tumor tissues, (2) lack of selectivity for tumoral cells and (3) endosomal sequestration of the particles upon internalization. In addition, their open porous structure may lead to premature drug release, consequently affecting healthy tissues and decreasing the efficacy of the treatment. First, this review will provide a comprehensive and systematic overview of the different approximations that have been implemented into mesoporous silica nanoparticles to overcome each of such biological barriers. Afterward, the potential premature and non-specific drug release from these mesoporous nanocarriers will be addressed by introducing the concept of stimuli-responsive gatekeepers, which endow the particles with on-demand and localized drug delivery.

Mesoporous Silica Nanoparticles for the Treatment of Complex Bone Diseases: Bone Cancer, Bone Infection and Osteoporosis

Bone diseases, such as bone cancer, bone infection and osteoporosis, constitute a major issue for modern societies as a consequence of their progressive ageing. Even though these pathologies can be currently treated in the clinic, some of those treatments present drawbacks that may lead to severe complications. For instance, chemotherapy lacks great tumor tissue selectivity, affecting healthy and diseased tissues. In addition, the inappropriate use of antimicrobials is leading to the appearance of drug-resistant bacteria and persistent biofilms, rendering current antibiotics useless. Furthermore, current antiosteoporotic treatments present many side effects as a consequence of their poor bioavailability and the need to use higher doses. In view of the existing evidence, the encapsulation and selective delivery to the diseased tissues of the different therapeutic compounds seem highly convenient. In this sense, silica-based mesoporous nanoparticles offer great loading capacity within their pores, the possibility of modifying the surface to target the particles to the malignant areas and great biocompatibility. This manuscript is intended to be a comprehensive review of the available literature on complex bone diseases treated with silica-based mesoporous nanoparticles-the further development of which and eventual translation into the clinic could bring significant benefits for our future society.

New insights towards mesoporous silica nanoparticles as a technological platform for chemotherapeutic drugs delivery

Mesoporous silica nanoparticles (MSNs) displays interesting properties for biomedical applications such as high chemical stability, large surface area and tunable pores diameters and volumes, allowing the incorporation of large amounts of drugs, protecting them from deactivation and degradation processes acting as an excellent nanoplatform for drug delivery. However, the functional MSNs do not present the ability to transport the therapeutics without any leakage until reach the targeted cells causing side effects. On the other hand, the hydroxyls groups available on MSNs surface allows the conjugation of specific molecules which can binds to the overexpressed Enhanced Growth Factor Receptor (EGFR) in many tumors, representing a potential strategy for the cancer treatment. Beyond that, the targeting molecules conjugate onto mesoporous surface increase its cell internalization and act as gatekeepers blocking the mesopores controlling the drug release. In this context, multifunctional MSNs emerge as stimuli-responsive controlled drug delivery systems (CDDS) to overcome drawbacks as low internalization, premature release before to reach the region of interest, several side effects and low effectiveness of the current treatments. This review presents an overview of MSNs fabrication methods and its properties that affects drug delivery as well as stimuli-responsive CDDS for cancer treatment.

Advances in mesoporous silica nanoparticles for targeted stimuli-responsive drug delivery: an update

INTRODUCTION

Mesoporous silica nanoparticles (MSNs) are outstanding nanoplatforms for drug delivery. Herein, the most recent advances to turn MSN-based carriers into minimal side effect drug delivery agents are covered.

AREAS COVERED

This review summarizes the scientific advances dealing with MSNs for targeted and stimuli-responsive drug delivery since 2015. Delivery aspects to diseased tissues together with approaches to obtain smart MSNs able to respond to internal or external stimuli and their applications are here described. Special emphasis is done on the combination of two or more stimuli on the same nanoplatform and on combined drug therapy.

EXPERT OPINION

The use of MSNs in nanomedicine is a promising research field because they are outstanding platforms for treating different pathologies. This is possible thanks to their structural, chemical, physical and biological properties. However, there are certain issues that should be overcome to improve the suitability of MSNs for clinical applications. All materials must be properly characterized prior to their in vivo evaluation; furthermore, preclinical in vivo studies need to be standardized to demonstrate the MSNs clinical translation potential.

Magnetic bio-metal-organic framework nanocomposites decorated with folic acid conjugated chitosan as a promising biocompatible targeted theranostic system for cancer treatment

In this work, a multifunctional magnetic Bio-Metal-Organic Framework (Fe₃O₄@Bio-MOF) coated with folic acid-chitosan conjugate (FC) was successfully prepared for tumor-targeted delivery of curcumin (CUR) and 5-fluorouracil (5-FU) simultaneously. Bio-MOF nanocomposite based on CUR as organic linker and zinc as metal ion was prepared by hydrothermal method in the presence of amine-functionalized Fe₃O₄ magnetic nanoparticles (Fe₃O₄@NH₂ MNPs). 5-FU was loaded in the magnetic Bio-MOF and the obtained nanocarrier was then coated with FC network. The prepared nanocomposite (NC) was fully characterized by high resolution-transmission electron microscope (HR-TEM), field emission scanning electron microscopy (FE-SEM), Dynamic light scattering (DLS), X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA), vibrating sample magnetometry (VSM), nuclear magnetic resonance (NMR), and UV-vis analyses. In vitro release study showed controlled release of CUR and 5-FU in acidic pH confirming high selectivity and performance of the carrier in cancerous microenvironments. The selective uptake of 5-FU-loaded Fe₃O₄@Bio-MOF-FC by folate receptor-positive MDA-MB-231 cells was investigated and verified. The ultimate nanocarrier exhibited no significant toxicity, while drug loaded nanocarrier showed selective and higher toxicity against the cancerous cells than normal cells. SDS PAGE was also utilized to determine the protein pattern attached on the surface of the nanocarriers. In vitro and in vivo MRI studies showed negative signal enhancement in tumor confirming the ability of the nanocarrier to be applied as diagnostic agent. Owing to the selective anticancer release and cellular uptake, acceptable blood compatibility as well as suitable T₂ MRI contrast performance, the target nanocarrier could be considered as favorable theranostic in breast cancer.

Enhancement of therapeutic effect in breast cancer with a steroid-conjugated ruthenium complex

A hybrid metallic prodrug for targeting PR-positive breast cancer therapy was prepared, which revealed significantly in vivo antitumor effect.

Water-soluble ferrocene complexes (WFCs) functionalized silica nanospheres for WFC delivery in HepG2 tumor therapy

Silica-encapsulated nanospheres of water-soluble ferrocene complexes WFCs@SiO₂ and WFCs@SiO₂@glutaraldehyde (GA) were first synthesized by a facile inverse-microemulsion method. The surface functional groups, particle size, and morphologies of nanospheres were characterized by IR spectra, UV-vis absorption spectra, dynamic light scattering (DLS) and SEM images. Single-crystal X-ray diffraction was used to confirm the molecular structure of free ferrocenyl-pyrazol ligand (L) and three WFCs, namely, [Ni(C₂₂H₁₄F₆FeN₄O₄)(H₂O)₄] (5a), [Mg(C₂₂H₁₄F₆FeN₄O₄)(H₂O)₄]·3H₂O (5b), and [Ba(C₂₂H₁₄F₆FeN₄O₄)(H₂O)₃] (5c). The electrochemical properties of 5a-5c were explored by cyclic voltammetry. The WFCs-loading capacities of 5a-5c in WFCs@SiO₂ were found to be 38.4, 38.2, and 38.1 μg/mg, respectively. Cell studies under two drug delivery modes (free diffusion and endocytosis) were carried out by MTT cell-survival assays and morphological observation of HepG2 cells. It's interesting that the cytotoxicity of WFCs against HepG2 was increased by applying silica nanocarriers. Compared to WFCs@SiO₂, the modification of GA on the spherical surface provided not only the better water-dispersity but also additional functional groups for further modification of other pharmacophores. The novel nanocarrier system for WFC delivery present a novel concept-of-proof method to protect varieties of affordable metal-based anticancer agents in physiological conditions and provided experimental basis for future studies focusing on drug delivery of other WFCs.

111In-labelled polymeric nanoparticles incorporating a ruthenium-based radiosensitizer for EGFR-targeted combination therapy in oesophageal cancer cells

Radiolabelled, drug-loaded nanoparticles may combine the theranostic properties of radionuclides, the controlled release of chemotherapy and cancer cell targeting. Here, we report the preparation of poly(lactic-co-glycolic acid) (PLGA) nanoparticles surface conjugated to DTPA-hEGF (DTPA = diethylenetriaminepentaacetic acid, hEGF = human epidermal growth factor) and encapsulating the ruthenium-based DNA replication inhibitor and radiosensitizer Ru(phen)2(tpphz)2+ (phen = 1,10-phenanthroline, tpphz = tetrapyridophenazine) Ru1. The functionalized PLGA surface incorporates the metal ion chelator DTPA for radiolabelling and the targeting ligand for EGF receptor (EGFR). Nanoparticles radiolabelled with 111In are taken up preferentially by EGFR-overexpressing oesophageal cancer cells, where they exhibit radiotoxicity through the generation of cellular DNA damage. Moreover, nanoparticle co-delivery of Ru1 alongside 111In results in decreased cell survival compared to single-agent formulations; an effect that occurs through DNA damage enhancement and an additive relationship between 111In and Ru1. Substantially decreased uptake and radiotoxicity of nanoparticles towards normal human fibroblasts and oesophageal cancer cells with normal EGFR levels is observed. This work demonstrates nanoparticle co-delivery of a therapeutic radionuclide plus a ruthenium-based radiosensitizer can achieve combinational and targeted therapeutic effects in cancer cells that overexpress EGFR.

Facile Synthesis of Chitosan Capped Mesoporous Silica Nanoparticles: A pH Responsive Smart Delivery Platform for Raloxifene Hydrochloride

An encapsulation of model drug raloxifene hydrochloride (RAL) inside the chitosan decorated pH responsive mesoporous system has a greater potential for accumulating in the tumor cells. The present study involves synthesis of surface modified mesoporous silica nanoparticles (MSN) with the aim of achieving pH sensitive drug delivery system. A silanol skeleton of MSN has been productively modified to amine intermediate which served as a firm platform to adapt chitosan grafted assembly and systematically evaluated. RAL incorporation inside the featured mesopores was performed employing novel immersion solvent evaporation methodology and evaluated further. The pH responsive behavior of formulated nano framework was studied at three different pH of a phosphate buffer saline individually. The in vitro cell viability assay on MCF-7 breast carcinoma cells was performed in time and concentration dependent manner. Finally, the hemolysis assay of designed nanoparticle was accomplished to envisage the hemocompatibility. The outcome of characterization details unveiled a perfect 2D hexagonal spherical structure gifted with higher surface area and optimum pore size for designed nanoparticles. The higher percentage grafting of amine and chitosan residue, i.e., 4.01 and 28.51% respectively along with 31.89 and 33.57% RAL loading efficiency made MSNs more attractive and applicable. Eventually, in vitro release study exhibited higher RAL release in acidic media for extended time periods confirming successful formation of pH responsive nanoparticle having controlled release property. Conclusively potential of designed nanosystem to serve efficient anti-cancer remedy was confirmed by superior behaviour of chitosan grafted MSN towards MCF-7 cells with supreme hemocompatibility.

pH-responsive nanoreservoirs based on hyaluronic acid end-capped mesoporous silica nanoparticles for targeted drug delivery

Mesoporous silica nanoparticles (MSNs) are greatly appealing for efficient drug delivery due to their excellent drug loading capacities. However, it remains as a major challenge to realize site-specific controlled release with MSNs. This work examines a smart pH-responsive drug release system using MSNs for CD44-targeting drug delivery. Specifically, hyaluronic acid (HA) was applied as an end-capping agent to seal drug loads inside the mesoporous of MSNs through the acid labile hydrazine bonds. HA exposed on the surface of the particles can also serve as a targeting agent at the same time, enable site specific targeting toward CD-44 overexpressing cells. The system showed a good stability at physiological pHs, yet drug release could be triggered in response to changes in pH. Further studies showed that the HA-fabricated particles could achieve much enhanced cellular uptake via CD44 receptor-mediated endocytosis by Hela cells (CD44 receptor-positive), and as a result, doxorubicin-loaded MSNs exhibited significantly enhanced drug efficacy toward cancer cells overexpressing CD44 receptor (IC₅₀ = 0.56 μg/mL), whereas the normal cells showed weakly cytotoxicity (IC₅₀ = 1.03 μg/mL). Such a fabrication strategy may provide a new platform for preparation of high performance drug delivery systems for cancer therapy.

Recent developments in the nanostructured materials functionalized with ruthenium complexes for targeted drug delivery to tumors

In recent years, the field of metal-based drugs has been dominated by other existing precious metal drugs, and many researchers have focused their attention on the synthesis of various ruthenium (Ru) complexes due to their potential medical and pharmaceutical applications. The beneficial properties of Ru, which make it a highly promising therapeutic agent, include its variable oxidation states, low toxicity, high selectivity for diseased cells, ligand exchange properties, and the ability to mimic iron binding to biomolecules. In addition, Ru complexes have favorable adsorption properties, along with excellent photochemical and photophysical properties, which make them promising tools for photodynamic therapy. At present, nanostructured materials functionalized with Ru complexes have become an efficient way to administer Ru-based anticancer drugs for cancer treatment. In this review, the recent developments in the nanostructured materials functionalized with Ru complexes for targeted drug delivery to tumors are discussed. In addition, information on "traditional" (ie, non-nanostructured) Ru-based cancer therapies is included in a precise manner.

An enhanced chemotherapeutic effect facilitated by sonication of MSN

Sonodynamic therapy (SDT) is a non-invasive therapeutic modality for cancer treatment.