Functionalized mesoporous silica nanoparticles and biomedical applications

Since the first report in early 1990s, mesoporous silica nanoparticles (MSNs) have progressively attracted the attention of scientists due to their potential applications in physic, energy storage, imaging, and especially in biomedical engineering. Owning the unique physiochemical properties, such as highly porosity, large surface area and pore volume, functionalizable, tunable pore and particle sizes and biocompatibility, and high loading cavity, MSNs offer efficient encapsulation and then controlled release, and in some cases, intracellular delivery of bioactive molecules for biomedical applications. During the last decade, functionalized MSNs that show respond upon the surrounding stimulus changes, such as temperature, pH, redox, light, ultrasound, magnetic or electric fields, enzyme, redox, ROS, glucose, and ATP, or their combinations, have continuously revolutionized their potential applications in biomedical engineering. Therefore, this review focuses on discussion the recent fabrication of functionalized MSNs and their potential applications in drug delivery, therapeutic treatments, diagnostic imaging, and biocatalyst. In addition, some potential clinical applications and challenges will also be discussed.

Multi-functional nanoparticles as theranostic agents for the treatment & imaging of pancreatic cancer

Theranostics has received considerable attention since both therapy and imaging modalities can be integrated into a single nanocarrier. In this study, fluorescent iron oxide (FIO) nanoparticles and gemcitabine (G) encapsulated poly(lactide-co-glycolide) (PLGA) nanospheres (PGFIO) conjugated with human epidermal growth factor receptor 2, (HER-2) antibody (HER-PGFIO) were prepared and characterized. HER-PGFIO showed the magnetic moment of 10emu/g, relaxivity (r₂) of 773mM^-1s^-1 and specific absorption rate (SAR) of 183W/g. HER-PGFIO showed a sustained release of gemcitabine for 11days in PBS (pH 7.4). In vitro cytotoxicity evaluation of HER-PGFIO in 3D MIAPaCa-2 cultures showed 50% inhibitory concentration (IC₅₀) of 0.11mg/mL. Subcutaneous tumor xenografts of MIAPaCa-2 in SCID mice were developed and the tumor regression study at the end of 30days showed significant tumor regression (86±3%) in the HER-PGFIO with magnetic hyperthermia (MHT) treatment group compared to control group. In vivo MRI imaging showed the enhanced contrast in HER-PGFIO+MHT treated group compared to control. HER-PGFIO showed significant tumor regression and enhanced MRI in treatment groups, which could be an effective nanocarrier system for the treatment of pancreatic cancer.

STATEMENT OF SIGNIFICANCE

Combination therapies are best suitable to treat pancreatic cancer. Theranostics are the next generation therapeutics with both imaging and treatment agents encapsulated in a single nanocarrier. The novelty of the present work is the development of targeted nanocarrier that provides chemotherapy, thermotherapy and MRI imaging properties. The present work is the next step in developing the nanocarriers for pancreatic cancer treatment. Different treatment modalities embedding into a single nanocarrier is the biggest challenge that was achieved without compromising the functionality of each other. The surface modification of polymeric nanocarriers for antibody binding and their multifunctional abilities will appeal to wider audience.

Development of nanotheranostics against metastatic breast cancer--A focus on the biology & mechanistic approaches

Treatment for metastatic breast cancer still remains to be a challenge since the currently available diagnostic and treatment strategies fail to detect the micro-metastasis resulting in higher mortality rate. Moreover, the lack of specificity to target circulating tumor cells is also a factor. In addition, currently available imaging modalities to identify the secondaries vary with respect to various metastatic anatomic areas and size of the tumor. The drawbacks associated with the existing clinical management of the metastatic breast cancer demands the requirement of multifunctional nanotheranostics, which could diagnose at macro- and microscopic level, target the solid as well as circulating tumor cells and control further progression with the simultaneous evaluation of treatment response in a single platform. However, without the understanding of the biology as well as preferential homing ability of circulating tumor cells at distant organs, it is quite impossible to address the existing challenges in the present diagnostics and therapeutics against the breast cancer metastasis. Hence this review outlines the severity of the problem, basic biology and organ specificity with the sequential steps for the secondary progression of disease followed by the various mechanistic approaches in diagnosis and therapy at different stages.

A novel efficient mesoporous silica assisted green emitting phosphors-an exotic remote phosphor with high quantum yield

The MPS assisted remote phosphor attached proto-type LED exhibits a very strong green emission and this can be utilized as an efficient green component for various applications apart from the white LED productions.

Synthesis of a novel hierarchical mesoporous organic–inorganic nanohybrid using polyhedral oligomericsilsesquioxane bricks

A novel mesoporous silica with high surface area and ordered porosity has been developed using N-methylamino POSS and dichloromethylsilane.

Interaction between dipolar lipid headgroups and charged nanoparticles mediated by water dipoles and ions

In this work, a theoretical model describing the interaction between a positively or negatively charged nanoparticle and neutral zwitterionic lipid bilayers is presented. It is shown that in the close vicinity of the positively charged nanoparticle, the zwitterionic lipid headgroups are less extended in the direction perpendicular to the membrane surface, while in the vicinity of the negatively charged nanoparticle, the headgroups are more extended. This result coincides with the calculated increase in the osmotic pressure between the zwitterionic lipid surface and positively charged nanoparticle and the decrease of osmotic pressure between the zwitterionic lipid surface and the negatively charged nanoparticle. Our theoretical predictions agree well with the experimentally determined fluidity of a lipid bilayer membrane in contact with positively or negatively charged nanoparticles. The prospective significance of the present work is mainly to contribute to better understanding of the interactions of charged nanoparticles with a zwitterionic lipid bilayer, which may be important in the efficient design of the lipid/nanoparticle nanostructures (like liposomes with encapsulated nanoparticles), which have diverse biomedical applications, including targeted therapy (drug delivery) and imaging of cancer cells.

Magnetoluminescent light switches--dual modality in DNA detection

The synthesis and properties of two responsive magnetoluminescent iron oxide nanoparticles for dual detection of DNA by MRI and luminescence spectroscopy are presented. These magnetoluminescent agents consist of iron oxide nanoparticles conjugated with metallointercalators via a polyethylene glycol linker. Two metallointercalators were investigated: Ru(bpy')(phen)(dppz), which turns on upon DNA intercalation, and Eu-DOTA-Phen, which turns off. The characteristic light-switch responses of the metallointercalators are not affected by the iron oxide nanoparticles; upon binding to DNA the luminescence of the ruthenium complexes increases by ca. 20-fold, whereas that of the europium complex is >95% quenched. Additionally, the 17-20 nm magnetite cores, having permeable PEG coatings and stable dopamide anchors, render the two constructs efficient responsive contrast agents for MRI with unbound longitudinal and transverse relaxivities of 12.4-9.2 and 135-128 mM(-1)(Fe)s(-1), respectively. Intercalation of the metal complexes in DNA results in the formation of large clusters of nanoparticles with a resultant decrease of both r1 and r2 by 32-63% and 24-38%, respectively. The potential application of these responsive magnetoluminescent assemblies and their reversible catch-and-release properties for the purification of DNA is presented.

Surface modification of iron oxide nanoparticles by biocompatible polymers for tissue imaging and targeting

Superparamagnetic iron oxide nanoparticles (SPIONs) are excellent MR contrast agents when coated with biocompatible polymers such as hydrophilic synthetic polymers, proteins, polysaccharides, and lipids, which improve their stability and biocompatibility and reduce their aggregation. Various biocompatible materials, coated or conjugated with targeting moieties such as galactose, mannose, folic acid, antibodies and RGD, have been applied to SPION surfaces to provide tissue specificity to hepatocytes, macrophages, and tumor regions in order to reduce non-specific uptake and improve biocompatibility. This review discusses the recent progress in the development of biocompatible and hydrophilic polymers for improving stability of SPIONs and describes the carbohydrates based biocompatible materials that are providing SPIONs with cell/tissue specificity as ligands.

Preparation and Characterization of Promoted Fe-V/SiO2Nanocatalysts for Oxidation of Alcohols

A series of SiO2supported iron-vanadium catalysts were prepared using sol-gel and wetness impregnation methods. This research investigates the effects of V and Cu on the structure and morphology of Fe/SiO2catalysts. The SiO2supported catalyst with the highest specific surface area and pore volume was obtained when it is containing 40 wt.% Fe, 15 wt.% V, and 2 wt.% Cu. Characterization of prepared catalysts was carried out by powder X-ray diffraction (XRD), scanning electron microcopy (SEM), vibrating sample magnetometry (VSM), Fourier transform infrared (FT-IR) spectrometry, temperature program reduction (TPR), N2physisorption, and thermal analysis methods such as thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The Fe-V/SiO2catalyst promoted with 2 wt.% of Cu exhibited typical ferromagnetic behavior at room temperature with a saturation magnetization value of 11.44 emu/g. This character of catalyst indicated great potential for application in magnetic separation technologies. The prepared catalyst was found to act as an efficient recoverable nanocatalyst for oxidation reaction of alcohols to aldehydes and ketones in aqueous media under mild condition. Moreover, the catalyst was reused five times without significant degradation in catalytic activity and performance.