Beyond Traditional Hyperthermia: In Vivo Cancer Treatment with Magnetic-Responsive Mesoporous Silica Nanocarriers

Ultrasound-mediated delivery of Pik3cb shRNA using magnetic nanoparticles for the treatment of in-stent restenosis in a rat balloon-injured model

The aim of the present work was to examine the effect of polyethylene glycol (PEG)-coated superparamagnetic iron oxide (SPIO) nanoparticles carrying Pik3cb short hairpin RNA (shRNA) in the prevention of restenosis with the aid of ultrasound and a magnetic field. SPIO is a type of contrast agent used in medical imaging to enhance the visibility of specific tissues or organs. It consists of tiny iron oxide nanoparticles that can be targeted to specific areas of interest in the body. PEG-coated SPIO nanoparticles carrying Pik3cb shRNA (SPIO-shPik3cb) were prepared, and the particle size and zeta potential of PEG-coated SPIO nanoparticles with and without Pik3cb shRNA were examined. After a right common artery balloon-injured rat model was established, the rats were randomly divided into four groups, and the injured arteries were transfected with SPIO-shPik3cb, saline, SPIO-shcontrol and naked shRNA Pik3cb. During the treatment, each group was placed under a magnetic field and was transfected with the aid of ultrasound. Rats were sacrificed, and the tissue was harvested for analysis after 14 days. The results suggested that the mean particle size and zeta potential of SPIO-shPik3cbs were 151.45 ± 11 nm and 10 mV, respectively. SPIO-shPik3cb showed higher transfection efficiency and significantly inhibited the intimal thickening compared with naked Pik3cb shRNA in vascular smooth muscle cells (VSMCs) (*P < 0.05). Moreover, SPIO-shPik3cb could also significantly downregulate the expression of pAkt protein compared with naked Pik3cb shRNA. According to the results, SPIO-shPik3cb can remarkably inhibit the intimal thickening under a combination of magnetic field exposure and ultrasound.

Inorganic nanocarriers for siRNA delivery for cancer treatments

RNA interference is one of the emerging methodologies utilized in the treatment of a wide variety of diseases including cancer. This method specifically uses therapeutic RNAs (TpRNAs) like small interfering RNAs (siRNAs) to regulate/silence the cancer-linked genes, thereby minimizing the distinct activities of the cancer cells while aiding in their apoptosis. But, many complications arise during the transport/delivery of these TpRNAs that include poor systemic circulation, instability/degradation inside the body environment, no targeting capacity and also low cellular internalization. These difficulties can be overcome by using nanocarriers to deliver the TpRNAs inside the cancer cells. The following are the various categories of nanocarriers-viral vectors (e.g. lentivirus and adenovirus) and non-viral nanocarriers (self-assembling nanocarriers and inorganic nanocarriers). Viral vectors suffer from disadvantages like high immunogenicity compared to the non-viral nanocarriers. Among non-viral nanocarriers, inorganic nanocarriers gained significant attention as their inherent properties (like magnetic properties) can aid in the effective cellular delivery of the TpRNAs. Most of the prior reports have discussed about the delivery of TpRNAs through self-assembling nanocarriers; however very few have reviewed about their delivery using the inorganic nanoparticles. Therefore, in this review, we have mainly focussed on the delivery of TpRNAs-i.e. siRNA, especially programmed death ligand-1 (PD-L1), survivin, B-cell lymphoma-2 (Bcl-2), vascular endothelial growth factor and other siRNAs using the inorganic nanoparticles-mainly magnetic, metal and silica nanoparticles. Moreover, we have also discussed about the combined delivery of these TpRNAs along with chemotherapeutic drugs (mainly doxorubicin) andin vitroandin vivotherapeutic effectiveness.

Drug-Loaded Lipid Magnetic Nanoparticles for Combined Local Hyperthermia and Chemotherapy against Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is a devastating tumor of the central nervous system, currently missing an effective treatment. The therapeutic gold standard consists of surgical resection followed by chemotherapy (usually with temozolomide, TMZ) and/or radiotherapy. TMZ does not, however, provide significant survival benefit after completion of treatment because of development of chemoresistance and of heavy side effects of systemic administration. Improvement of conventional treatments and complementary therapies are urgently needed to increase patient survival and quality of life. Stimuli-responsive lipid-based drug delivery systems offer promising prospects to overcome the limitations of the current treatments. In this work, multifunctional lipid-based magnetic nanovectors functionalized with the peptide angiopep-2 and loaded with TMZ (Ang-TMZ-LMNVs) were tested to enhance specific GBM therapy on an in vivo model. Exposure to alternating magnetic fields (AMFs) enabled magnetic hyperthermia to be performed, that works in synergy with the chemotherapeutic agent. Studies on orthotopic human U-87 MG-Luc2 tumors in nude mice have shown that Ang-TMZ-LMNVs can accumulate and remain in the tumor after local administration without crossing over into healthy tissue, effectively suppressing tumor invasion and proliferation and significantly prolonging the median survival time when combined with the AMF stimulation. This powerful synergistic approach has proven to be a robust and versatile nanoplatform for an effective GBM treatment.

Evaluation of the osteoconductivity and the degradation of novel hydroxyapatite/polyurethane combined with mesoporous silica microspheres in a rabbit osteomyelitis model

Bone defects caused by osteomyelitis can lead to severe disability. Surgeons still face significant challenges in treating bone defects. Nano-hydroxyapatite (n-HA) plays an important role in bone tissue engineering due to its excellent biocompatibility and osteoconductivity. Levofloxacin (Levo) was encapsulated in mesoporous silica nanoparticles (MSNs) via electrostatic attraction to serve as a drug delivery system. MSNs were incorporated with n-HA and polyurethane (PU). The degradation and osteoconductivity properties of these novel composite scaffolds and their effectiveness in treating chronic osteomyelitis in a rabbit model were assessed. Gross pathology, radiographic imaging, micro-computed tomography, Van Gieson staining, and hematoxylin and eosin staining were conducted at 6 and 12 weeks. The group of composite scaffolds combining n-HA/PU with MSNs containing 5 mg Levo (n-HA/PU + Nano +5 mg Levo) composite scaffolds showed superior antibacterial properties compared to the other groups. At 12 weeks, the n-HA/PU + Nano +5 mg Levo composite scaffolds group exhibited significantly greater volume of new trabecular bone formation compared to the other three groups. The surface of the novel composite scaffolds exhibited degradation after 6 weeks implantation. The internal structure of the scaffolds collapsed noticeably after 12 weeks of implantation. The rate of material degradation corresponded to the rate of new bone ingrowth. This novel composite scaffold, which is biodegradable and osteoconductive, has potential as a drug delivery system for treating chronic osteomyelitis accompanied by bone defects.

Nanomedical research and development in Spain: improving the treatment of diseases from the nanoscale

The new and unique possibilities that nanomaterials offer have greatly impacted biomedicine, from the treatment and diagnosis of diseases, to the specific and optimized delivery of therapeutic agents. Technological advances in the synthesis, characterization, standardization, and therapeutic performance of nanoparticles have enabled the approval of several nanomedicines and novel applications. Discoveries continue to rise exponentially in all disease areas, from cancer to neurodegenerative diseases. In Spain, there is a substantial net of researchers involved in the development of nanodiagnostics and nanomedicines. In this review, we summarize the state of the art of nanotechnology, focusing on nanoparticles, for the treatment of diseases in Spain (2017-2022), and give a perspective on the future trends and direction that nanomedicine research is taking.

Iron Oxide@Mesoporous Silica Core-Shell Nanoparticles as Multimodal Platforms for Magnetic Resonance Imaging, Magnetic Hyperthermia, Near-Infrared Light Photothermia, and Drug Delivery

The design of core-shell nanocomposites composed of an iron oxide core and a silica shell offers promising applications in the nanomedicine field, especially for developing efficient theranostic systems which may be useful for cancer treatments. This review article addresses the different ways to build iron oxide@silica core-shell nanoparticles and it reviews their properties and developments for hyperthermia therapies (magnetically or light-induced), combined with drug delivery and MRI imaging. It also highlights the various challenges encountered, such as the issues associated with in vivo injection in terms of NP-cell interactions or the control of the heat dissipation from the core of the NP to the external environment at the macro or nanoscale.

Recent advances in magnetic nanocarriers for tumor treatment

Magnetic nanocarriers are nano-platforms that integrate multiple moieties based on magnetic nanoparticles for diagnostic and therapeutic purposes. In recent years, they have become an advanced platform for tumor treatment due to their wide application in magnetic resonance imaging (MRI), biocatalysis, magneto-thermal therapy (MHT), and photoresponsive therapy. Drugs loaded into magnetic nanocarriers can efficiently be directed to targeted areas by precisely reshaping their structural properties. Magnetic nanocarriers allow us to track the location of the therapeutic agent, continuously control the therapeutic process and eventually assess the efficacy of the treatment. They are typically used in synergistic therapeutic applications to achieve precise and effective tumor treatment. Here we review their latest applications in tumor treatment, including stimuli-responsive drug delivery, MHT, photoresponsive therapy, immunotherapy, gene therapy, and synergistic therapy. We consider reducing toxicity, improving antitumor efficacy, and the targeting accuracy of magnetic nanocarriers. The challenges of their clinical translation and prospects in cancer therapy are also discussed.

Natural Biopolymers as Smart Coating Materials of Mesoporous Silica Nanoparticles for Drug Delivery

In recent years, the functionalization of mesoporous silica nanoparticles (MSNs) with different types of responsive pore gatekeepers have shown great potential for the formulation of drug delivery systems (DDS) with minimal premature leakage and site-specific controlled release. New nanotechnological approaches have been developed with the objective of utilizing natural biopolymers as smart materials in drug delivery applications. Natural biopolymers are sensitive to various physicochemical and biological stimuli and are endowed with intrinsic biodegradability, biocompatibility, and low immunogenicity. Their use as biocompatible smart coatings has extensively been investigated in the last few years. This review summarizes the MSNs coating procedures with natural polysaccharides and protein-based biopolymers, focusing on their application as responsive materials to endogenous stimuli. Biopolymer-coated MSNs, which conjugate the nanocarrier features of mesoporous silica with the biocompatibility and controlled delivery provided by natural coatings, have shown promising therapeutic outcomes and the potential to emerge as valuable candidates for the selective treatment of various diseases.

Biomimetic cell-derived nanocarriers in cancer research

Nanoparticles have now long demonstrated capabilities that make them attractive to use in biology and medicine. Some of them, such as lipid nanoparticles (SARS-CoV-2 vaccines) or metallic nanoparticles (contrast agents) are already approved for their use in the clinic. However, considering the constantly growing body of different formulations and the huge research around nanomaterials the number of candidates reaching clinical trials or being commercialized is minimal. The reasons behind being related to the "synthetic" and "foreign" character of their surface. Typically, nanomaterials aiming to develop a function or deliver a cargo locally, fail by showing strong off-target accumulation and generation of adverse responses, which is connected to their strong recognition by immune phagocytes primarily. Therefore, rendering in negligible numbers of nanoparticles developing their intended function. While a wide range of coatings has been applied to avoid certain interactions with the surrounding milieu, the issues remained. Taking advantage of the natural cell membranes, in an approach that resembles a cell transfer, the use of cell-derived surfaces has risen as an alternative to artificial coatings or encapsulation methods. Biomimetic technologies are based on the use of isolated natural components to provide autologous properties to the nanoparticle or cargo being encapsulated, thus, improving their therapeutic behavior. The main goal is to replicate the (bio)-physical properties and functionalities of the source cell and tissue, not only providing a stealthy character to the core but also taking advantage of homotypic properties, that could prove relevant for targeted strategies. Such biomimetic formulations have the potential to overcome the main issues of approaches to provide specific features and identities synthetically. In this review, we provide insight into the challenges of nano-biointerfaces for drug delivery; and the main applications of biomimetic materials derived from specific cell types, focusing on the unique strengths of the fabrication of novel nanotherapeutics in cancer therapy.

Mesoporous Silica Nanoparticles-Based Nanoplatforms: Basic Construction, Current State, and Emerging Applications in Anticancer Therapeutics

In recent years, researchers are developing novel nanoparticles for diagnostic applications using imaging techniques and for therapeutic purposes through drug delivery techniques. The unique physical and chemical properties of mesoporous silica nanoparticles (MSNs) make it possible to integrate a variety of commonly used therapeutic and imaging agents to construct a multimodal synergistic anticancer drug delivery system. Herein, recent advances in MSNs synthesis for drug delivery and smart response applications are reviewed. First, synthetic strategies for the fabrication of ordered MSNs, hollow MSNs, core-shell structured MSNs, dendritic MSNs, and biodegradable MSNs are outlined. Then, the recent research progress in designing functional MSN materials with various controlled release mechanisms in anticancer therapy is discussed, and new properties are introduced to suggest the latest design requirements as drug delivery materials. The review also highlights significant achievements in bioimaging using MSNs and their multifunctional counterparts as delivery vehicles. Finally, personal views on key directions for future work in this area are presented.

Exploiting recent trends for the synthesis and surface functionalization of mesoporous silica nanoparticles towards biomedical applications

Rapid progress in developing multifunctional nanocarriers for drug delivery has been observed in recent years. Inorganic mesoporous silica nanocarriers (MSNs), emerged as an ideal candidate for gene/drug delivery with distinctive morphological features. These ordered carriers of porous nature have gained unique attention due to their distinctive features. Moreover, transformation can be made to these nanocarriers in terms of pores size, pores volume, and particle size by altering specific parameters during synthesis. These ordered porous materials have earned special attention as a drug carrier for treating multiple diseases. Herein, we highlight the strategies employed in synthesizing and functionalizing these versatile nanocarriers. In addition, the various factors that influence their sizes and morphological features were also discussed. The article also summarizes the recent advancements and strategies for drug and gene delivery by rendering smarter MSNs by incorporating functional groups on their surfaces. Averting off-target effects through various capping strategies is a massive milestone for the induction of stimuli-responsive nanocarriers that brings out a great revolution in the biomedical field.

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MSNs serve as an ideal candidate for gene/drug delivery with unique and excellent attributes.

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MSNs surface can be functionalized using specific materials to impart unique structural features.

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Functionalization of MSNs with stimuli-responsive molecules can act as gatekeepers by responding to the desired stimulus after uncapping.

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These capping agents act as vital targeting agents in developing MSNs being employed in various biomedical applications.

Nanomaterials: small particles show huge possibilities for cancer immunotherapy

With the economy's globalization and the population's aging, cancer has become the leading cause of death in most countries. While imposing a considerable burden on society, the high morbidity and mortality rates have continuously prompted researchers to develop new oncology treatment options. Anti-tumor regimens have evolved from early single surgical treatment to combined (or not) chemoradiotherapy and then to the current stage of tumor immunotherapy. Tumor immunotherapy has undoubtedly pulled some patients back from the death. However, this strategy of activating or boosting the body's immune system hardly benefits most patients. It is limited by low bioavailability, low response rate and severe side effects. Thankfully, the rapid development of nanotechnology has broken through the bottleneck problem of anti-tumor immunotherapy. Multifunctional nanomaterials can not only kill tumors by combining anti-tumor drugs but also can be designed to enhance the body's immunity and thus achieve a multi-treatment effect. It is worth noting that the variety of nanomaterials, their modifiability, and the diversity of combinations allow them to shine in antitumor immunotherapy. In this paper, several nanobiotics commonly used in tumor immunotherapy at this stage are discussed, and they activate or enhance the body's immunity with their unique advantages. In conclusion, we reviewed recent advances in tumor immunotherapy based on nanomaterials, such as biological cell membrane modification, self-assembly, mesoporous, metal and hydrogels, to explore new directions and strategies for tumor immunotherapy.

Effect of the Silica-Magnetite Nanocomposite Coating Functionalization on the Doxorubicin Sorption/Desorption

A series of new composite materials based on Fe3O4 magnetic nanoparticles coated with SiO2 (or aminated SiO2) were synthesized. It has been shown that the use of N-(phosphonomethyl)iminodiacetic acid (PMIDA) to stabilize nanoparticles before silanization ensures the increased content of a SiO2 phase in the Fe3O4@SiO2 nanocomposites (NCs) in comparison with materials obtained under similar conditions, but without PMIDA. It has been demonstrated for the first time that the presence of PMIDA on the surface of NCs increases the level of Dox loading due to specific binding, while surface modification with 3-aminopropylsilane, on the contrary, significantly reduces the sorption capacity of materials. These regularities were in accordance with the results of quantum chemical calculations. It has been shown that the energies of Dox binding to the functional groups of NCs are in good agreement with the experimental data on the Dox sorption on these NCs. The mechanisms of Dox binding to the surface of NCs were proposed: simultaneous coordination of Dox on the PMIDA molecule and silanol groups at the NC surface leads to a synergistic effect in Dox binding. The synthesized NCs exhibited pH-dependent Dox release, as well as dose-dependent cytotoxicity in in vitro experiments. The cytotoxic effects of the studied materials correspond to their calculated IC50 values. NCs with a SiO2 shell obtained using PMIDA exhibited the highest effect. At the same time, the presence of PMIDA in NCs makes it possible to increase the Dox loading, as well as to reduce its desorption rate, which may be useful in the design of drug delivery vehicles with a prolonged action. We believe that the data obtained can be further used to develop stimuli-responsive materials for targeted cancer chemotherapy.

Physically stimulus-responsive nanoparticles for therapy and diagnosis

Nanoparticles offer numerous advantages in various fields of science, particularly in medicine. Over recent years, the use of nanoparticles in disease diagnosis and treatments has increased dramatically by the development of stimuli-responsive nano-systems, which can respond to internal or external stimuli. In the last 10 years, many preclinical studies were performed on physically triggered nano-systems to develop and optimize stable, precise, and selective therapeutic or diagnostic agents. In this regard, the systems must meet the requirements of efficacy, toxicity, pharmacokinetics, and safety before clinical investigation. Several undesired aspects need to be addressed to successfully translate these physical stimuli-responsive nano-systems, as biomaterials, into clinical practice. These have to be commonly taken into account when developing physically triggered systems; thus, also applicable for nano-systems based on nanomaterials. This review focuses on physically triggered nano-systems (PTNSs), with diagnostic or therapeutic and theranostic applications. Several types of physically triggered nano-systems based on polymeric micelles and hydrogels, mesoporous silica, and magnets are reviewed and discussed in various aspects.

Magnetic-Responsive Doxorubicin-Containing Materials Based on Fe3O4 Nanoparticles with a SiO2/PEG Shell and Study of Their Effects on Cancer Cell Lines

Novel nanocomposite materials based on Fe₃O₄ magnetic nanoparticles (MNPs) coated with silica and covalently modified by [(3-triethoxysilyl)propyl]succinic acid–polyethylene glycol (PEG 3000) conjugate, which provides a high level of doxorubicin (Dox) loading, were obtained. The efficiency of Dox desorption from the surface of nanomaterials under the action of an alternating magnetic field (AMF) in acidic and neutral media was evaluated. Their high cytotoxicity against tumor cells, as well as the drug release upon application of AMF, which leads to an increase in the cytotoxic effect, was demonstrated.

Functionalized Magnetic Nanoparticles for Alternating Magnetic Field- or Near Infrared Light-Induced Cancer Therapies

The multi-faceted nature of functionalized magnetic nanoparticles (fMNPs) is well-suited for cancer therapy. These nanocomposites can also provide a multimodal platform for targeted cancer therapy due to their unique magnetic guidance characteristics. When induced by an alternating magnetic field (AMF), fMNPs can convert the magnetostatic energy to heat for magnetic hyperthermia (MHT), as well as for controlled drug release. Furthermore, with the ability to convert near-infrared (NIR) light energy to heat energy, fMNPs have attracted interest for photothermal therapy (PTT). Other than MHT and PTT, fMNPs also have a place in combination cancer therapies, such as chemo-MHT, chemo-PTT, and chemo-PTT-photodynamic therapy, among others, due to their versatile properties. Thus, this review presents multifunctional nanocomposites based on fMNPs for cancer therapies, induced by an AMF or NIR light. We will first discuss the different fMNPs induced with an AMF for cancer MHT and chemo-MHT. Secondly, we will discuss fMNPs irradiated with NIR lasers for cancer PTT and chemo-PTT. Finally, fMNPs used for dual-mode AMF + NIR-laser-induced magneto-photo-hyperthermia (MPHT) will be discussed.

The Therapeutic Effects of DDP/CD44-shRNA Nanoliposomes in AMF on Ovarian Cancer

Background

Globally, ovarian cancer is one of the most common gynecological malignant tumors, and the overall curative effect has been unsatisfactory for years. Exploring and investigating novel therapeutic strategy for ovarian cancer are an imperative need.

Methods

Using manganese zinc ferrite nanoparticles (PEG-MZF-NPs) as gene transferring vector and drug delivery carrier, a new combinatorial regimen for the target treatment of ovarian cancer by integrating CD44-shRNA, DDP (cisplatin) and magnetic fluid hyperthermia (MFH) together was designed and investigated in vivo and in vitro in this study.

Results

PEG-MZF-NPs/DDP/CD44-shRNA nanoliposomes were successfully prepared, and TEM detection indicated that they were 15–20 nm in diameter, with good magnetothermal effect in AMF, similar to the previously prepared PEG-MZF-NPs. Under the action of AMF, PEG-MZF-NPs/shRNA/DDP nanoliposomes effectively inhibited ovarian tumors’ growth, restrained the cancer cells’ proliferation and invasion, and promoted cell apoptosis. VEGF, survivin, BCL-2, and BCL-xl proteins significantly decreased, while caspase-3 and caspase-9 proteins markedly increased both in vitro and in vivo, far better than any of the individual therapies did. Moreover, no significant effects were found on bone marrow hematopoiesis and liver and kidney function of nude mice intervened by the combinatorial therapeutic regimen.

Conclusion

In the present study, we developed PEG-MZF-NPs/DDP/CD44-shRNA magnetic nanoliposomes and inaugurated an integrated therapy through the synergistic effect of MFH, gene therapy, and chemotherapy, and it shows a satisfactory therapeutic effect on ovarian cancer in vitro and in vivo, much better than any single treatment regimen did, with no significant side effects. This study provides a new promising method for ovarian cancer treatment.

Nanoarchitectured prototypes of mesoporous silica nanoparticles for innovative biomedical applications

Despite exceptional morphological and physicochemical attributes, mesoporous silica nanoparticles (MSNs) are often employed as carriers or vectors. Moreover, these conventional MSNs often suffer from various limitations in biomedicine, such as reduced drug encapsulation efficacy, deprived compatibility, and poor degradability, resulting in poor therapeutic outcomes. To address these limitations, several modifications have been corroborated to fabricating hierarchically-engineered MSNs in terms of tuning the pore sizes, modifying the surfaces, and engineering of siliceous networks. Interestingly, the further advancements of engineered MSNs lead to the generation of highly complex and nature-mimicking structures, such as Janus-type, multi-podal, and flower-like architectures, as well as streamlined tadpole-like nanomotors. In this review, we present explicit discussions relevant to these advanced hierarchical architectures in different fields of biomedicine, including drug delivery, bioimaging, tissue engineering, and miscellaneous applications, such as photoluminescence, artificial enzymes, peptide enrichment, DNA detection, and biosensing, among others. Initially, we give a brief overview of diverse, innovative stimuli-responsive (pH, light, ultrasound, and thermos)- and targeted drug delivery strategies, along with discussions on recent advancements in cancer immune therapy and applicability of advanced MSNs in other ailments related to cardiac, vascular, and nervous systems, as well as diabetes. Then, we provide initiatives taken so far in clinical translation of various silica-based materials and their scope towards clinical translation. Finally, we summarize the review with interesting perspectives on lessons learned in exploring the biomedical applications of advanced MSNs and further requirements to be explored.

Incorporation of Superparamagnetic Iron Oxide Nanoparticles into Collagen Formulation for 3D Electrospun Scaffolds

Nowadays, there is an ever-increasing interest in the development of systems able to guide and influence cell activities for bone regeneration. In this context, we have explored for the first time the combination of type-I collagen and superparamagnetic iron oxide nanoparticles (SPIONs) to design magnetic and biocompatible electrospun scaffolds. For this purpose, SPIONs with a size of 12 nm were obtained by thermal decomposition and transferred to an aqueous medium via ligand exchange with dimercaptosuccinic acid (DMSA). The SPIONs were subsequently incorporated into type-I collagen solutions to prove the processability of the resulting hybrid formulation by means of electrospinning. The optimized method led to the fabrication of nanostructured scaffolds composed of randomly oriented collagen fibers ranging between 100 and 200 nm, where SPIONs resulted distributed and embedded into the collagen fibers. The SPIONs-containing electrospun structures proved to preserve the magnetic properties of the nanoparticles alone, making these matrices excellent candidates to explore the magnetic stimuli for biomedical applications. Furthermore, the biological assessment of these collagen scaffolds confirmed high viability, adhesion, and proliferation of both pre-osteoblastic MC3T3-E1 cells and human bone marrow-derived mesenchymal stem cells (hBM-MSCs).

Our contributions to applications of mesoporous silica nanoparticles

Our contributions to mesoporous silica materials in the field of biomedicine are reported in this article. This perspective article represents our work in the basics of the material, preparing different ranges of mesoporous silica nanoparticles with different diameters and with varied pore sizes. We demonstrated the high loading capacity of these materials. Additionally, the possibility of functionalizing both internal and external surface with different organic or inorganic moieties allowed the development of stimuli-responsive features which allowed a proper control on the administered dose. In addition, we have demonstrated that these carriers are not toxic, and we have also ensured that the load reaches its destination without affecting healthy tissues. STATEMENT OF SIGNIFICANCE: This paper presents my personal opinion and background on a hot topic as mesoporous silica nanoparticles for drug delivery. To this aim it provides a comprehensive and historical overview on the innovative contributions of my research group to this rapidly expanding field of research.

Nanoantibiotics Based in Mesoporous Silica Nanoparticles: New Formulations for Bacterial Infection Treatment

This review focuses on the design of mesoporous silica nanoparticles for infection treatment. Written within a general context of contributions in the field, this manuscript highlights the major scientific achievements accomplished by professor Vallet-Regí's research group in the field of silica-based mesoporous materials for drug delivery. The aim is to bring out her pivotal role on the envisage of a new era of nanoantibiotics by using a deep knowledge on mesoporous materials as drug delivery systems and by applying cutting-edge technologies to design and engineer advanced nanoweapons to fight infection. This review has been divided in two main sections: the first part overviews the influence of the textural and chemical properties of silica-based mesoporous materials on the loading and release of antibiotic molecules, depending on the host-guest interactions. Furthermore, this section also remarks on the potential of molecular modelling in the design and comprehension of the performance of these release systems. The second part describes the more recent advances in the use of mesoporous silica nanoparticles as versatile nanoplatforms for the development of novel targeted and stimuli-responsive antimicrobial nanoformulations for future application in personalized infection therapies.

Iron Oxide Nanoparticles: Physicochemical Characteristics and Historical Developments to Commercialization for Potential Technological Applications

Iron oxide nanoparticles (IONPs) have gained increasing attention in various biomedical and industrial sectors due to their physicochemical and magnetic properties. In the biomedical field, IONPs are being developed for enzyme/protein immobilization, magnetofection, cell labeling, DNA detection, and tissue engineering. However, in some established areas, such as magnetic resonance imaging (MRI), magnetic drug targeting (MDT), magnetic fluid hyperthermia (MFH), immunomagnetic separation (IMS), and magnetic particle imaging (MPI), IONPs have crossed from the research bench, received clinical approval, and have been commercialized. Additionally, in industrial sectors IONP-based fluids (ferrofluids) have been marketed in electronic and mechanical devices for some time. This review explores the historical evolution of IONPs to their current state in biomedical and industrial applications.

Nanoparticles for Magnetic Heating: When Two (or More) Is Better Than One

The increasing use of magnetic nanoparticles as heating agents in biomedicine is driven by their proven utility in hyperthermia therapeutic treatments and heat-triggered drug delivery methods. The growing demand of efficient and versatile nanoheaters has prompted the creation of novel types of magnetic nanoparticle systems exploiting the magnetic interaction (exchange or dipolar in nature) between two or more constituent magnetic elements (magnetic phases, primary nanoparticles) to enhance and tune the heating power. This process occurred in parallel with the progress in the methods for the chemical synthesis of nanostructures and in the comprehension of magnetic phenomena at the nanoscale. Therefore, complex magnetic architectures have been realized that we classify as: (a) core/shell nanoparticles; (b) multicore nanoparticles; (c) linear aggregates; (d) hybrid systems; (e) mixed nanoparticle systems. After a general introduction to the magnetic heating phenomenology, we illustrate the different classes of nanoparticle systems and the strategic novelty they represent. We review some of the research works that have significantly contributed to clarify the relationship between the compositional and structural properties, as determined by the synthetic process, the magnetic properties and the heating mechanism.

Atomic Resolution Electron Microscopy: A Key Tool for Understanding the Activity of Nano-Oxides for Biomedical Applications

Transition metal oxides constitute one of the most fruitful sources of materials with continuously increasing potential applications prompted by the expectations derived from the reduction of the particle size. The recent advances in transmission electron microscopy, because of the development of lenses, have made it possible to reach atomic resolution, which can provide answers regarding the performance of the transition metal nano-oxides. This critical information is related not only to the ability to study their microstructural characteristics but also their local composition and the oxidation state of the transition metal. Exploring these features is a well-known task in nano-oxides for energy and electronic technologies, but they are not so commonly used for elucidating the activity of these oxides for biomedical applications. Nevertheless, the identification at the atomic level of a certain dopant or the unambiguous determination of the oxidation state of a transition metal in a nano-oxide can be important questions to be answered in a certain biomedical application. In this work, we provide several examples in transition metal nano-oxides to show how atomic-resolution electron microscopy can be a key tool for its understanding.

Comprehensive review on ultrasound-responsive theranostic nanomaterials: mechanisms, structures and medical applications

The field of theranostics has been rapidly growing in recent years and nanotechnology has played a major role in this growth. Nanomaterials can be constructed to respond to a variety of different stimuli which can be internal (enzyme activity, redox potential, pH changes, temperature changes) or external (light, heat, magnetic fields, ultrasound). Theranostic nanomaterials can respond by producing an imaging signal and/or a therapeutic effect, which frequently involves cell death. Since ultrasound (US) is already well established as a clinical imaging modality, it is attractive to combine it with rationally designed nanoparticles for theranostics. The mechanisms of US interactions include cavitation microbubbles (MBs), acoustic droplet vaporization, acoustic radiation force, localized thermal effects, reactive oxygen species generation, sonoluminescence, and sonoporation. These effects can result in the release of encapsulated drugs or genes at the site of interest as well as cell death and considerable image enhancement. The present review discusses US-responsive theranostic nanomaterials under the following categories: MBs, micelles, liposomes (conventional and echogenic), niosomes, nanoemulsions, polymeric nanoparticles, chitosan nanocapsules, dendrimers, hydrogels, nanogels, gold nanoparticles, titania nanostructures, carbon nanostructures, mesoporous silica nanoparticles, fuel-free nano/micromotors.

Advanced mesoporous silica nanocarriers in cancer theranostics and gene editing applications

Targeted nanomaterials for cancer theranostics have been the subject of an expanding volume of research studies in recent years. Mesoporous silica nanoparticles (MSNs) are particularly attractive for such applications due to possibilities to synthesize nanoparticles (NPs) of different morphologies, pore diameters and pore arrangements, large surface areas and various options for surface functionalization. Functionalization of MSNs with different organic and inorganic molecules, polymers, surface-attachment of other NPs, loading and entrapping cargo molecules with on-desire release capabilities, lead to seemingly endless prospects for designing advanced nanoconstructs exerting multiple functions, such as simultaneous cancer-targeting, imaging and therapy. Describing composition and multifunctional capabilities of these advanced nanoassemblies for targeted therapy (passive, ligand-functionalized MSNs, stimuli-responsive therapy), including one or more modalities for imaging of tumors, is the subject of this review article, along with an overview of developments within a novel and attractive research trend, comprising the use of MSNs for CRISPR/Cas9 systems delivery and gene editing in cancer. Such advanced nanconstructs exhibit high potential for applications in image-guided therapies and the development of personalized cancer treatment.

Exosome-based hybrid nanostructures for enhanced tumor targeting and hyperthermia therapy

Recently, natural exosomes have attracted attention as an ideal drug carrier to overcome the limitations of existing drug delivery systems which are toxicity induction and low cancer-targeting performance. In this study, we propose an exosome-based hybrid nanostructure (EHN) with improved targeting ability and therapeutic efficacy against colorectal cancer by using exosomes isolated from the tumor cell line as a drug carrier. The proposed EHN can have high biocompatibility by using exosomes, a biologically derived material, and show improved targeting performance by adding a tumor-targeting ligand (folic acid). In addition, the proposed EHN is capable of chemotherapy because doxorubicin, an anticancer drug, is encapsulated by the exosome with high efficiency, and it can induce hyperthermia therapy because of the magnetic nanoparticles (MNPs) attached to the surface of exosomes. Through in vitro and in vivo experiments using a xenograft tumor mouse model, it was confirmed that the proposed EHN could exhibit increased apoptosis and excellent tumor growth inhibition ability. Therefore, the proposed EHN is expected to overcome the limitations of existing drug delivery systems and be utilized as an effective drug delivery system in cancer treatment.

Application of iron/barium ferrite/carbon-coated iron nanocrystal composites in transcatheter arterial chemoembolization of hepatocellular carcinoma

Transcatheter arterial chemoembolization (TACE) has been widely used in clinical practice as a first-line treatment for unresectable hepatocellular carcinoma (HCC). However, the current therapeuticeffect of TACE is far from satisfactory and thus requires further improvement. TACE combined with multifunctional magnetic particles may be a promising approach for the treatment of HCC. In this study, we designed a new magnetic drug carrier system consisting of micron-sized iron powder, barium ferrite (BaFe₁₂O₁₉), and carbon-coated iron nanocrystals (CCINs). CCINs possess properties, such as high drug loading and sustained release. BaFe₁₂O₁₉ could attract both CCINs and iron powder to form larger clusters after magnetization. Altogether, the triple therapeutic effects of chemotherapeutic enhancement, embolization, and thermal ablation could be realized herein. Further experiments indicate that the system has a high drug-loading capacity, good controlled-release effect, and no significant cytotoxicity. Under the action of a medium-frequency magnetic induction device, the magnetic induction temperature could reach 43 °C in one min while the maximum temperature of 70.8 °C could be reached in 2.5 h. Overall, this new carrier system displayed excellent antitumor effects in a mouse model. Our findings demonstrate the great application prospects of this system in TACE for HCC.

Mesoporous Silica Nanoparticles: Properties and Strategies for Enhancing Clinical Effect

Due to the theragnostic potential of mesoporous silica nanoparticles (MSNs), these were extensively investigated as a novel approach to improve clinical outcomes. Boasting an impressive array of formulations and modifications, MSNs demonstrate significant in vivo efficacy when used to identify or treat myriad malignant diseases in preclinical models. As MSNs continue transitioning into clinical trials, a thorough understanding of the characteristics of effective MSNs is necessary. This review highlights recent discoveries and advances in MSN understanding and technology. Specific focus is given to cancer theragnostic approaches using MSNs. Characteristics of MSNs such as size, shape, and surface properties are discussed in relation to effective nanomedicine practice and projected clinical efficacy. Additionally, tumor-targeting options used with MSNs are presented with extensive discussion on active-targeting molecules. Methods for decreasing MSN toxicity, improving site-specific delivery, and controlling release of loaded molecules are further explained. Challenges facing the field and translation to clinical environments are presented alongside potential avenues for continuing investigations.

Engineered non-invasive functionalized dendrimer/dendron-entrapped/complexed gold nanoparticles as a novel class of theranostic (radio)pharmaceuticals in cancer therapy

Nanomedicine represents a very significant contribution in current cancer treatment; in addition to surgical intervention, radiation and chemotherapeutic agents that unfortunately also kill healthy cells, inducing highly deleterious and often life-threatening side effects in the patient. Of the numerous nanoparticles used against cancer, gold nanoparticles had been developed for therapeutic applications. Inter alia, a large variety of dendrimers, i.e. soft artificial macromolecules, have turned up as non-viral functional nanocarriers for entrapping drugs, imaging agents, and targeting molecules. This review will provide insights into the design, synthesis, functionalization, and development in biomedicine of engineered functionalized hybrid dendrimer-tangled gold nanoparticles in the domain of cancer theranostic. Several aspects are highlighted and discussed such as 1) dendrimer-entrapped gold(0) hybrid nanoparticles for the targeted imaging and treatment of cancer cells, 2) dendrimer encapsulating gold(0) nanoparticles (Au DENPs) for the delivery of genes, 3) Au DENPs for drug delivery applications, 4) dendrimer encapsulating gold radioactive nanoparticles for radiotherapy, and 5) dendrimer/dendron-complexed gold(III) nanoparticles as technologies to take down cancer cells.

Fluorescence resonance energy transfer monitoring of pH-responsive doxorubicin release from carbon dots/aptamer functionalized magnetic mesoporous silica

Aim: To develop a novel theranostic nanoplatform for simultaneous fluorescent monitoring and stimuli-triggered drug delivery. Materials & methods: Different microscopic and spectroscopic techniques were used for the characterization of nanocarriers. MCF-7 and human umbilical vein endothelial cell lines were cultured and treated with different doses of doxorubicin-loaded nanocarriers. The cell viability and drug release were studied using MTT assay and fluorescence microscopy. Results: Biocompatible and mono-disperse nanocarriers represent hollow and mesoporous structures with the calculated surface area of 552.83 m².g^-1, high magnetic activity (12.6 emu.g^-1), appropriate colloidal stability and high drug loading capacity (up to 61%). Conclusion: Taxane-based carbon dots act as the pH-responsive gatekeepers for the controlled release of doxorubicin into cancer cells and provide a fluorescence resonance energy transfer system for real-time monitoring of drug delivery.

Critical Parameters to Improve Pancreatic Cancer Treatment Using Magnetic Hyperthermia: Field Conditions, Immune Response, and Particle Biodistribution

Magnetic hyperthermia (MH) was used to treat a murine model of pancreatic cancer. This type of cancer is generally characterized by the presence of dense stroma that acts as a barrier for chemotherapeutic treatments. Several alternating magnetic field (AMF) conditions were evaluated using three-dimensional (3D) cell culture models loaded with magnetic nanoparticles (MNPs) to determine which conditions were producing a strong effect on the cell viability. Once the optimal AMF conditions were selected, in vivo experiments were carried out using similar frequency and field amplitude parameters. A marker of the immune response activation, calreticulin (CALR), was evaluated in cells from a xenograft tumor model after the MH treatment. Moreover, the distribution of nanoparticles within the tumor tissue was assessed by histological analysis of tumor sections, observing that the exposure to the alternating magnetic field resulted in the migration of particles toward the inner parts of the tumor. Finally, a relationship between an inadequate body biodistribution of the particles after their intratumoral injection and a significant decrease in the effectiveness of the MH treatment was found. Animals in which most of the particles remained in the tumor area after injection showed higher reductions in the tumor volume growth in comparison with those animals in which part of the particles were found also in the liver and spleen. Therefore, our results point out several factors that should be considered to improve the treatment effectiveness of pancreatic cancer by magnetic hyperthermia.

Expanding nanoparticle multifunctionality: size-selected cargo release and multiple logic operations

Physically stimulated nanoparticles that deliver size-selected cargo and function as logic gates are reported. To achieve this goal the particle requires multiple components, and we recognized early on that the components, not just the released cargo, could be used to demonstrate logic operations (OR and AND logic). For stimuli, we chose two non-invasive types, red light and alternating magnetic fields (AMF), because they both have potential biological relevance. To realize cargo delivery with size selection and logic operations, we mechanized the surface of core@shell nanoparticles with a superparamagnetic core that generates localized heating when exposed to an AMF, and a mesoporous silica shell into which cargo molecules with different sizes were loaded. We demonstrate the core@shell nanoparticles can load the dual cargos with different sizes and subsequently release the smaller (∼0.5 nm) and bigger (∼2 nm) cargos in succession when stimulated by a red light followed by an AMF. Finally, we demonstrate that the multi-component nanoparticles could function as nanoparticle-based Boolean logic gates where AMF and red light served as the two inputs and the release of small cargo, and free cyclodextrin served as the outputs. The construction of two Boolean logic gates (OR, and AND) was realized.

Stimuli-Responsive Iron Oxide Nanotheranostics: A Versatile and Powerful Approach for Cancer Therapy

Recent advancements in unravelling elements of cancer biology involved in disease progression and treatment resistance have highlighted the need for a holistic approach to effectively tackle cancer. Stimuli-responsive nanotheranostics based on iron oxide nanoparticles are an emerging class of versatile nanomedicines with powerful capabilities to "seek, sense, and attack" multiple components of solid tumors. In this work, the rationale for using iron oxide nanoparticles and the basic physical principles that impact their function in biomedical applications are reviewed. Subsequently, recent advances in the integration of iron oxide nanoparticles with various stimulus mechanisms to facilitate the development of stimuli-responsive nanotheranostics for application in cancer therapy are summarized. The integration of an iron oxide core with various surface coating mechanisms results in the generation of hybrid nanoconstructs with capabilities to codeliver a wide variety of highly potent anticancer therapeutics and immune modulators. Finally, emerging future directions and considerations for their clinical translation are touched upon.

Rapid tumor inhibition via magnetic hyperthermia regulated by caspase 3 with time-dependent clearance of iron oxide nanoparticles

Among conventional cancer therapies, radio-frequency magnetic hyperthermia (MHT) has widely been investigated for use with magnetic nanoparticles (MNPs). However, the majority of in vivo biodistribution studies have tested very low MNP dosages (equivalent to magnetic resonance imaging (MRI) applications) to check for clearance rate; which is far below the clinical dose of MHT. Due to this poor validation in preclinical scenarios, quite a few MNPs already in clinical use were later discontinued, on grounds of unexpected clinical outcomes in terms of inflammation, and prolonged clearance in vivo. By exploiting an economical method of synthesis, we have developed chitosan-coated Fe₃O₄ nanoparticles with high heating efficiency performance. Their anti-tumor response was evaluated in an ectopic tumor model of C6 glioblastoma by MHT. The intratumoral injection of MNPs on days 1 and 7 resulted in rapid tumor inhibition rate of 69.4% within 8 days, with complete inhibition within 32 days, and no recurrence recorded over a 5-month follow-up. Notably, the MNP-mediated MHT therapy achieved the highest degree of therapeutic efficacy required for complete tumor ablation by combining controlled temperature range (<44 °C), reduced MNP dosage; much lower than in most reported studies, and AMF parameters (time of exposure and frequency) within the clinical safety limit. Periodic body weight measurements confirmed negligible adverse side effects in rats. The anti-tumor activity was validated by severe apoptosis (TUNEL, cleaved Caspase-3), reduced proliferation (Ki 67) and disrupted vasculature (CD 31) in the Fe₃O₄-MHT-treated group. Real-time gene expression of pro-inflammatory cytokines (IL-6, TNF-α, IL-1α, IL-1β) confirmed the intratumoral activation of IL-6, suggesting the role of immunomodulation in triggering the adaptive immune response for faster tumor regression in the treated group. In addition, the biodistribution and clearance rate of MNPs monitored using ICP-OES confirmed their time-dependent biodegradation via excretion (urine, feces), phagocytosis (liver) and circulatory system (blood), with negligible deposition in other major organs (kidney, heart, lungs). Although we could not show complete clearance of our MNPs within the time frame tested, future studies should focus on combining MHT with immunotherapy, and target tumors at a much-reduced iron dose, consequently improving in vivo clearance rate, and hence overcoming the limitations of MHT in clinical therapy.

Paclitaxel-loaded magnetic nanocrystals for tumor neovascular-targeted theranostics: an amplifying synergistic therapy combining magnetic hyperthermia with chemotherapy

A combination of chemotherapy and targeted magnetic hyperthermia (TMH) via a designed magnetic nanocrystal (MNC) drug delivery system was considered as an effective tumor synergistic therapy strategy. In this paper, we successfully synthesized tumor neovascular-targeted Mn-Zn ferrite MNCs, which encapsulated paclitaxel (PTX) in a biocompatible PEG-phospholipid (DSPE-PEG2000) layer and surface, simultaneously coupled with a tripeptide of arginine-glycine-aspartic acid (RGD). The high-performance RGD-modified MNC loaded with PTX (MNCs-PTX@RGD) embodied excellent magnetic properties, including high-contrast magnetic resonance imaging (MRI) and remarkable magnetically induced heat generation ability. We established the mouse model bearing subcutaneous 4T1 breast tumor, and demonstrated that MNCs-PTX@RGD could be effectively located in the tumor neovascular epithelial cells under the guidance of in vivo MRI. Notably, MNCs-PTX@RGD could easily penetrate into the tumor tissue from the tumor-fenestrated vascular networks for capturing a sufficient temperature (around 43 °C) exposed to an alternative current magnetic field (ACMF, 2.58 kA m^-1, 390 kHz), leading to an effective TMH effect. Subsequently, the TMH-mediated temperature elevation accelerated the PTX release from the inner lipid layer, promoting the synergetic thermo-chemotherapy in vivo. The amplifying synergistic treatment strategy obviously improved the anti-tumor efficacy of MNCs-PTX@RGD, and simultaneously increased the survival time of the mice to more than 46 days, which provided a broad development prospect in clinical applications.

The Opportunities and Challenges of Silica Nanomaterial for Atherosclerosis

Atherosclerosis (AS) as the leading cause of cardiovascular and cerebrovascular events has been paid much attention all the time. With the continuous development of modern medical drug treatment, surgical treatment, interventional treatment and other methods, the mortality rate of AS has shown a downward trend, while the morbidity rate is still increasing. Oral lipid-lowering or anti-inflammatory drugs are generally used for early AS, but the relatively low accumulation efficiency in lesions and the unavoidable side effects required researchers to develop more effective drug delivery approaches for the therapy of AS. Mesoporous silica nanoparticles as nanocarrier for drug delivery have received extensive attentions due to their flexible size, high specific surface area, controlled pore volume, high drug loading capacity and excellent biocompatibility. Series of good reviews about the mesoporous silica nanoparticles loaded drugs for cancer therapy have been well documented. However, their roles as nanocarrier for drug delivery to treat AS have few reports. In this review, the applications and challenges of mesoporous silica nanomaterials in the field of the diagnosis and therapy of AS have been summarized. The classification, synthesis, formation mechanism, surface modification and functionalization of mesoporous silica nanomaterials which were closely related to the theranostic effect of AS have also been included. Last but not the least, the future prospects’ suggestions of mesoporous silica nanomaterial-based drug delivery system for AS are also provided.

Recent Progresses in Organic-Inorganic Nano Technological Platforms for Cancer Therapeutics

Nanotechnology offers promising tools in interdisciplinary research areas and getting an upsurge of interest in cancer therapeutics. Organic nanomaterials and inorganic nanomaterials bring revolutionary advancement in cancer eradication process. Oncology is achieving new heights under nano technological platform by expediting chemotherapy, radiotherapy, photo thermodynamic therapy, bio imaging and gene therapy. Various nanovectors have been developed for targeted therapy which acts as "Nano-bullets" for tumor cells selectively. Recently combinational therapies are catching more attention due to their enhanced effect leading towards the use of combined organicinorganic nano platforms. The current review covers organic, inorganic and their hybrid nanomaterials for various therapeutic action. The technological aspect of this review emphasizes on the use of inorganic-organic hybrids and combinational therapies for better results and also explores the future opportunities in this field.

Impact of Citrate and Lipid-Functionalized Magnetic Nanoparticles in Dehydropeptide Supramolecular Magnetogels: Properties, Design and Drug Release

Currently, the nanoparticle functionalization effect on supramolecular peptide-based hydrogels remains undescribed, but is expected to affect the hydrogels' self-assembly and final magnetic gel properties. Herein, two different functionalized nanoparticles: citrate-stabilized (14.4 ± 2.6 nm) and lipid-coated (8.9 ± 2.1 nm) magnetic nanoparticles, were used for the formation of dehydropeptide-based supramolecular magnetogels consisting of the ultra-short hydrogelator Cbz-L-Met-Z-ΔPhe-OH, with an assessment of their effect over gel properties. The lipid-coated nanoparticles were distributed along the hydrogel fibers, while citrate-stabilized nanoparticles were aggregated upon gelation, which resulted into a heating efficiency improvement and decrease, respectively. Further, the lipid-coated nanoparticles did not affect drug encapsulation and displayed improved drug release reproducibility compared to citrate-stabilized nanoparticles, despite the latter attaining a stronger AMF-trigger. This report points out that adsorption of nanoparticles to hydrogel fibers, which display domains that improve or do not affect drug encapsulation, can be explored as a means to optimize the development of supramolecular magnetogels to advance theranostic applications.

A Review of Mesoporous Silica Nanoparticle Delivery Systems in Chemo-Based Combination Cancer Therapies

Chemotherapy is an important anti-tumor treatment in clinic to date, however, the effectiveness of traditional chemotherapy is limited by its poor selectivity, high systemic toxicity, and multidrug resistance. In recent years, mesoporous silica nanoparticles (MSNs) have become exciting drug delivery systems (DDS) due to their unique advantages, such as easy large-scale production, adjustable uniform pore size, large surface area and pore volumes. While mesoporous silica-based DDS can improve chemotherapy to a certain extent, when used in combination with other cancer therapies MSN based chemotherapy exhibits a synergistic effect, greatly improving therapeutic outcomes. In this review, we discuss the applications of MSN DDS for a diverse range of chemotherapeutic combination anti-tumor therapies, including phototherapy, gene therapy, immunotherapy and other less common modalities. Furthermore, we focus on the characteristics of each nanomaterial and the synergistic advantages of the combination therapies. Lastly, we examine the challenges and future prospects of MSN based chemotherapeutic combination therapies.

Mesoporous Silica Nanoparticles as Theranostic Antitumoral Nanomedicines

Nanoparticles have become a powerful tool in oncology not only as carrier of the highly toxic chemotherapeutic drugs but also as imaging contrast agents that provide valuable information about the state of the disease and its progression. The enhanced permeation and retention effect for loaded nanocarriers in tumors allow substantial improvement of selectivity and safety of anticancer nanomedicines. Additionally, the possibility to design stimuli-responsive nanocarriers able to release their payload in response to specific stimuli provide an excellent control on the administered dosage. The aim of this review is not to present a comprehensive revision of the different theranostic mesoporous silica nanoparticles (MSN) which have been published in the recent years but just to describe a few selected examples to offer a panoramic view to the reader about the suitability and effectiveness of these nanocarriers in the oncology field.

Multifunctional Fe3O4-Au Nanoparticles for the MRI Diagnosis and Potential Treatment of Liver Cancer

Heterodimeric nanoparticles comprising materials with different functionalities are of great interest for fundamental research and biomedical/industrial applications. In this work, Fe₃O₄-Au nano-heterostructures were synthesized by a one-step thermal decomposition method. The hybrid nanoparticles comprise a highly crystalline 12 nm magnetite octahedron decorated with a single noble metal sphere of 6 nm diameter. Detailed analysis of the nanoparticles was performed by UV-visible spectroscopy, magnetometry, calorimetry and relaxometry studies. The cytotoxic effect of the nanoparticles in the human hepatic cell line Huh7 and PLC/PRF/5-Alexander was also assessed. These Fe₃O₄-Au bifunctional nanoparticles showed no significant cytotoxicity in these two cell lines. The nanoparticles showed a good theranostic potential for liver cancer treatment, since the r₂ relaxivity (166.5 mM⁻¹·s⁻¹ and 99.5 mM⁻¹·s⁻¹ in water and HepG2 cells, respectively) is higher than the corresponding values for commercial T₂ contrast agents and the Specific Absorption Rate (SAR) value obtained (227 W/g_Fe) is enough to make them suitable as heat mediators for Magnetic Fluid Hyperthermia. The gold counterpart can further allow the conjugation with different biomolecules and the optical sensing.

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.

Magnetic Nanoparticles as MRI Contrast Agents

Iron oxide nanoparticles (IONPs) have emerged as a promising alternative to conventional contrast agents (CAs) for magnetic resonance imaging (MRI). They have been extensively investigated as CAs due to their high biocompatibility and excellent magnetic properties. Furthermore, the ease of functionalization of their surfaces with different types of ligands (antibodies, peptides, sugars, etc.) opens up the possibility of carrying out molecular MRI. Thus, IONPs functionalized with epithelial growth factor receptor antibodies, short peptides, like RGD, or aptamers, among others, have been proposed for the diagnosis of various types of cancer, including breast, stomach, colon, kidney, liver or brain cancer. In addition to cancer diagnosis, different types of IONPs have been developed for other applications, such as the detection of brain inflammation or the early diagnosis of thrombosis. This review addresses key aspects in the development of IONPs for MRI applications, namely, synthesis of the inorganic core, functionalization processes to make IONPs biocompatible and also to target them to specific tissues or cells, and finally in vivo studies in animal models, with special emphasis on tumor models.