Amino‐polyvinyl Alcohol Coated Superparamagnetic Iron Oxide Nanoparticles are Suitable for Monitoring of Human Mesenchymal Stromal Cells In Vivo

Mesenchymal stromal cells (MSCs) are promising candidates in regenerative cell‐therapies. However, optimizing their number and route of delivery remains a critical issue, which can be addressed by monitoring the MSCs’ bio‐distribution in vivo using super‐paramagnetic iron‐oxide nanoparticles (SPIONs). In this study, amino‐polyvinyl alcohol coated (A‐PVA) SPIONs are introduced for cell‐labeling and visualization by magnetic resonance imaging (MRI) of human MSCs. Size and surface charge of A‐PVA‐SPIONs differ depending on their solvent. Under MSC‐labeling conditions, A‐PVA‐SPIONs have a hydrodynamic diameter of 42 ± 2 nm and a negative Zeta potential of 25 ± 5 mV, which enable efficient internalization by MSCs without the need to use transfection agents. Transmission X‐ray microscopy localizes A‐PVA‐SPIONs in intracellular vesicles and as cytosolic single particles. After identifying non‐interfering cell‐assays and determining the delivered and cellular dose, in addition to the administered dose, A‐PVA‐SPIONs are found to be non‐toxic to MSCs and non‐destructive towards their multi‐lineage differentiation potential. Surprisingly, MSC migration is increased. In MRI, A‐PVA‐SPION‐labeled MSCs are successfully visualized in vitro and in vivo. In conclusion, A‐PVA‐SPIONs have no unfavorable influences on MSCs, although it becomes evident how sensitive their functional behavior is towards SPION‐labeling. And A‐PVA‐SPIONs allow MSC‐monitoring in vivo.     

Microfluidic Assembly of Monodisperse Multistage pH‐Responsive Polymer/Porous Silicon Composites for Precisely Controlled Multi‐Drug Delivery

We report an advanced drug delivery platform for combination chemotherapy by concurrently incorporating two different drugs into microcompoistes with ratiometric control over the loading degree. Atorvastatin and celecoxib were selected as model drugs due to their different physicochemical properties and synergetic effect on colorectal cancer prevention and inhibition. To be effective in colorectal cancer prevention and inhibition, the produced microcomposite contained hypromellose acetate succinate, which is insoluble in acidic conditions but highly dissolving at neutral or alkaline pH conditions. Taking advantage of the large pore volume of porous silicon (PSi), atorvastatin was firstly loaded into the PSi matrix, and then encapsulated into the pH‐responsive polymer microparticles containing celecoxib by microfluidics in order to obtain multi‐drug loaded polymer/PSi microcomposites. The prepared microcomposites showed monodisperse size distribution, multistage pH‐response, precise ratiometric controlled loading degree towards the simultaneously loaded drug molecules, and tailored release kinetics of the loaded cargos. This attractive microcomposite platform protects the payloads from being released at low pH‐values, and enhances their release at higher pH‐values, which can be further used for colon cancer prevention and treatment. Overall, the pH‐responsive polymer/PSi‐based microcomposite can be used as a universal platform for the delivery of different drug molecules for combination therapy.     

Drug delivery: Magnetic Luminescent Porous Silicon Microparticles for Localized Delivery of Molecular Drug Payloads (Small 22/2010)

Magnetic manipulation, fluorescent tracking, and localized delivery of a drug payload to cancer cells in vitro is demonstrated, using nanostructured porous silicon microparticles as a carrier. The multifunctional microparticles are prepared by electrochemical porosification of a silicon wafer in a hydrofluoric acid‐containing electrolyte, followed by removal and fracture of the porous layer into particles using ultrasound. The intrinsically luminescent particles are loaded with superparamagnetic iron oxide nanoparticles and the anti‐cancer drug doxorubicin. The drug‐containing particles are delivered to human cervical cancer (HeLa) cells in vitro, under the guidance of a magnetic field. The high concentration of particles in the proximity of the magnetic field results in a high concentration of drug being released in that region of the Petri dish, and localized cell death is confirmed by cellular viability assay (Calcein AM).     

Magnetic Luminescent Porous Silicon Microparticles for Localized Delivery of Molecular Drug Payloads

Magnetic manipulation, fluorescent tracking, and localized delivery of a drug payload to cancer cells in vitro is demonstrated, using nanostructured porous silicon microparticles as a carrier. The multifunctional microparticles are prepared by electrochemical porosification of a silicon wafer in a hydrofluoric acid‐containing electrolyte, followed by removal and fracture of the porous layer into particles using ultrasound. The intrinsically luminescent particles are loaded with superparamagnetic iron oxide nanoparticles and the anti‐cancer drug doxorubicin. The drug‐containing particles are delivered to human cervical cancer (HeLa) cells in vitro, under the guidance of a magnetic field. The high concentration of particles in the proximity of the magnetic field results in a high concentration of drug being released in that region of the Petri dish, and localized cell death is confirmed by cellular viability assay (Calcein AM).     

Nanostructured medical device coatings based on self-assembled poly(lactic-co-glycolic acid) nanoparticles

Here we present a new method for providing nanostructured drug-loaded polymer films which enable control of film surface morphology and delivery of therapeutic agents. Silicon wafers were employed as models for implanted biomaterials and poly(lactic-co-glycolic acid) (PLGA) nanoparticles were assembled onto the silicon surface by electrostatic interaction. Monolayers of the PLGA particles were deposited onto the silicon surface upon incubation in an aqueous particle suspension. Particle density and surface coverage of the silicon wafers were varied by altering particle concentration, incubation time in nanoparticle suspension and ionic strength of the suspension. Dye loaded nanoparticles were prepared and assembled to silicon surface to form nanoparticle films. Fluorescence intensity measurements showed diffusion-controlled release of the dye over two weeks and atomic force microscopy (AFM) analysis revealed that these particles remained attached to the surface during the incubation time. This work suggests that coating implants with PLGA nanoparticles is a versatile technique which allows drug release from the implant surface and modulation of surface morphology.     

Sorafenib delivery nanoplatform based on superparamagnetic iron oxide nanoparticles magnetically targets hepatocellular carcinoma

Currently,sorafenib is the only systemic therapy capable of increasing overall survival of hepatocellular carcinoma patients.Unfortunately,its side effects,particularly its overall toxicity,limit the therapeutic response that can be achieved.Superparamagnetic iron oxide nanoparticles (SPIONs) are very attractive for drug delivery because they can be targeted to specific sites in the body through application of a magnetic field,thus improving intratumoral accumulation and reducing adverse effects.Here,nanoformulations based on polyethylene glycol modified phospholipid micelles,loaded with both SPIONs and sorafenib,were successfully prepared and thoroughly investigated by complementary techniques.This nanovector system provided effective drug delivery,had an average hydrodynamic diameter of about 125 nm,had good stability in aqueous medium,and allowed controlled drug loading.Magnetic analysis allowed accurate determination of the amount of SPIONs embedded in each micelle.An in vitro system was designed to test whether the SPION micelles can be efficiently held using a magnetic field under typical flow conditions found in the human liver.Human hepatocellular carcinoma (HepG2) cells were selected as an in vitro system to evaluate tumor cell targeting efficacy of the superparamagnetic micelles loaded with sorafenib.These experiments demonstrated that this delivery platform is able to enhance sorafenib's antitumor effectiveness by magnetic targeting.The magnetic nanovectors described here represent promising candidates for targeting specific hepatic tumor sites,where selective release of sorafenib can improve its efficacy and safety profile.     

Epirubicin‐Loaded Superparamagnetic Iron‐Oxide Nanoparticles for Transdermal Delivery: Cancer Therapy by Circumventing the Skin Barrier

The transdermal administration of chemotherapeutic agents is a persistent challenge for tumor treatments. A model anticancer agent, epirubicin (EPI), is attached to functionalized superparamagnetic iron‐oxide nanoparticles (SPION). The covalent modification of the SPION results in EPI–SPION, a potential drug delivery vector that uses magnetism for the targeted transdermal chemotherapy of skin tumors. The spherical EPI–SPION composite exhibits excellent magnetic responsiveness with a saturation magnetization intensity of 77.8 emu g^?1. They feature specific pH‐sensitive drug release, targeting the acidic microenvironment typical in common tumor tissues or endosomes/lysosomes. Cellular uptake studies using human keratinocyte HaCaT cells and melanoma WM266 cells demonstrate that SPION have good biocompatibility. After conjugation with EPI, the nanoparticles can inhibit WM266 cell proliferation; its inhibitory effect on tumor proliferation is determined to be dose‐dependent. In vitro transdermal studies demonstrate that the EPI–SPION composites can penetrate deep inside the skin driven by an external magnetic field. The magnetic‐field‐assisted SPION transdermal vector can circumvent the stratum corneum via follicular pathways. The study indicates the potential of a SPION‐based vector for feasible transdermal therapy of skin cancer.     

Characterizing Physical Properties of Superparamagnetic Nanoparticles in Liquid Phase Using Brownian Relaxation

Superparamagnetic iron oxide nanoparticles (SPIONs) have been extensively used as bioimaging contrast agents, heating sources for tumor therapy, and carriers for controlled drug delivery and release to target organs and tissues. These applications require elaborate tuning of the physical and magnetic properties of the SPIONs. The authors present here a search‐coil‐based method to characterize these properties. The nonlinear magnetic response of SPIONs to alternating current magnetic fields induces harmonic signals that contain information of these nanoparticles. By analyzing the phase lag and harmonic ratios in the SPIONs, the authors can predict the saturation magnetization, the average hydrodynamic size, the dominating relaxation processes of SPIONs, and the distinction between single‐ and multicore particles. The numerical simulations reveal that the harmonic ratios are inversely proportional to saturation magnetizations and core diameters of SPIONs, and that the phase lag is dependent on the hydrodynamic volumes of SPIONs, which corroborate the experimental results. Herein, the authors stress the feasibility of using search coils as a method to characterize physical and magnetic properties of SPIONs, which may be applied as building blocks in nanoparticle characterization devices.     

Preparation of Water-Dispersible and Biocompatible Iron Oxide Nanoparticles for MRI Agent

Highly monodisperse superparamagnetic iron oxide nanoparticles (SPIONs, 7.5 nm gamma- F₂O₃) were synthesized by thermal decomposition of iron pentacarbonyl and consecutive aeration in organic medium. By treating with a small amount of iron pentacarbonyl, Fe-rich surface has been formed on SPION. Water-dispersible SPIONs (SPION-MPA) were prepared by Fe-S covalent conjugation between Fe-rich SPION and mercaptopropionic acid (MPA) and then, transformed to SPION-MPA-dextran composite by physical adsorption of biocompatible polymer dextran. The hydrodynamic diameter of SPION-MPA-dextran was in the range of 225~237 nm in water. MR contrast and spin-spin relaxation intensity of our SPION-MPA-dextran were similar to those of the commercial products, Ferridex and Resovist.     

Neuroprotective Effect of Nerve Growth Factor Loaded in Porous Silicon Nanostructures in an Alzheimer's Disease Model and Potential Delivery to the Brain

Nerve growth factor (NGF) plays a vital role in reducing the loss of cholinergic neurons in Alzheimer's disease (AD). However, its delivery to the brain remains a challenge. Herein, NGF is loaded into degradable oxidized porous silicon (PSiO₂) carriers, which are designed to carry and continuously release the protein over a 1 month period. The released NGF exhibits a substantial neuroprotective effect in differentiated rat pheochromocytoma PC12 cells against amyloid‐beta (Aβ)‐induced cytotoxicity, which is associated with Alzheimer's disease. Next, two potential localized administration routes of the porous carriers into murine brain are investigated: implantation of PSiO₂ chips above the dura mater, and biolistic bombardment of PSiO₂ microparticles through an opening in the skull using a pneumatic gene gun. The PSiO₂‐implanted mice are monitored for a period of 8 weeks and no inflammation or adverse effects are observed. Subsequently, a successful biolistic delivery of these highly porous microparticles into a live‐mouse brain is demonstrated for the first time. The bombarded microparticles are observed to penetrate the brain and reach a depth of 150 µm. These results pave the way for using degradable PSiO₂ carriers as potential localized delivery systems for NGF to the brain.     

Cytotoxicity and Cell Cycle Effects of Bare and Poly(vinyl alcohol)‐Coated Iron Oxide Nanoparticles in Mouse Fibroblasts

Super‐paramagnetic iron oxide nanoparticles (SPIONs) are recognized as powerful biocompatible materials for use in various biomedical applications, such as drug delivery, magnetic‐resonance imaging, cell/protein separation, hyperthermia and transfection. This study investigates the impact of high concentrations of SPIONs on cytotoxicity and cell‐cycle effects. The interactions of surface‐saturated (via interactions with cell medium) bare SPIONs and those coated with poly(vinyl alcohol) (PVA) with adhesive mouse fibroblast cells (L929) are investigated using an MTT assay. The two SPION formulations are synthesized using a co‐precipitation method. The bare and coated magnetic nanoparticles with passivated surfaces both result in changes in cell morphology, possibly due to clustering through their magnetostatic effect. At concentrations ranging up to 80 × 10^?3 M , cells exposed to the PVA‐coated nanoparticles demonstrate high cell viability without necrosis and apoptosis. In contrast, significant apoptosis is observed in cells exposed to bare SPIONs at a concentration of 80 × 10^?3 M . Nanoparticle exposure (20–80 × 10^?3 M ) leads to variations in both apoptosis and cell cycle, possibly due to irreversible DNA damage and repair of oxidative DNA lesions, respectively. Additionally, the formation of vacuoles within the cells and granular cells indicates autophagy cell death rather than either apoptosis or necrosis.     

SPION‐Decorated Exosome Delivered BAY55‐9837 Targeting the Pancreas through Magnetism to Improve the Blood GLC Response

BAY55‐9837, a potential therapeutic peptide in the treatment of type 2 diabetes mellitus (T2DM), is capable of inducing glucose (GLC)‐dependent insulin secretion. However, the therapeutic benefit of BAY55‐9837 is limited by its short half‐life, lack of targeting ability, and poor blood GLC response. How to improve the blood GLC response of BAY55‐9837 is an existing problem that needs to be solved. In this study, a method for preparing BAY55‐9837‐loaded exosomes coupled with superparamagnetic iron oxide nanoparticle (SPIONs) with pancreas islet targeting activity and an enhanced blood GLC response with the help of an external magnetic force (MF) is demonstrated. The plasma half‐life of BAY55‐9837 loaded in exosome‐SPION is 27‐fold longer than that of BAY55‐9837. The active targeting property of SIPONs enables BAY‐exosomes to gain a favorable targeting property, which improves the BAY55‐9837 blood GLC response capacity with the help of an external MF. In vivo studies show that BAY‐loaded exosome‐based vehicle delivery enhances pancreas islet targeting under an external MF and markedly increases insulin secretion, thereby leading to the alleviation of hyperglycemia. The chronic administration of BAY‐exosome‐SPION/MF significantly improves glycosylated hemoglobin and lipid profiles. BAY‐exosome‐SPION/MF maybe a promising candidate for a peptide drug carrier for T2DM with a better blood GLC response.     

Stabilization of Polymer‐Hydrogel Capsules via Thiol–Disulfide Exchange

Polymer hydrogels are used in diverse biomedical applications including drug delivery and tissue engineering. Among different chemical linkages, the natural and reversible thiol–disulfide interconversion is extensively explored to stabilize hydrogels. The creation of macro‐, micro‐, and nanoscale disulfide‐stabilized hydrogels commonly relies on the use of oxidizing agents that may have a detrimental effect on encapsulated cargo. Herein an oxidization‐free approach to create disulfide‐stabilized polymer hydrogels via a thiol–disulfide exchange reaction is reported. In particular, thiolated poly(methacrylic acid) is used and the conditions of polymer crosslinking in solution and on colloidal porous and solid microparticles are established. In the latter case, removal of the core particles yields stable, hollow, disulfide‐crosslinked hydrogel capsules. Further, a procedure is developed to achieve efficient disulfide crosslinking of multilayered polymer films to obtain stable, liposome‐loaded polymer‐hydrogel capsules that contain functional enzymatic cargo within the liposomal subcompartments. This approach is envisaged to facilitate the development of biomedical applications of hydrogels, specifically those including fragile cargo.     

The development of stable aqueous suspensions of PEGylated SPIONs for biomedical applications

We report here the development of stable aqueous suspensions of biocompatible superparamagnetic iron oxide nanoparticles (SPIONs). These so-called ferrofluids are useful in a large spectrum of modern biomedical applications, including novel diagnostic tools and targeted therapeutics. In order to provide prolonged circulation times for the nanoparticles in?vivo, the initial iron oxide nanoparticles were coated with a biocompatible polymer poly(ethylene glycol) (PEG). To permit covalent bonding of PEG to the SPION surface, the latter was functionalized with a coupling agent, 3-aminopropyltrimethoxysilane (APS). This novel method of SPION PEGylation has been reproduced in numerous independent preparations. At each preparation step, particular attention was paid to determine the physico-chemical characteristics of the samples using a number of analytical techniques such as atomic absorption, Fourier transform infrared (FT-IR) spectroscopy and Raman spectroscopy, transmission electron microscopy (TEM), photon correlation spectroscopy (PCS, used for hydrodynamic diameter and zeta potential measurements) and magnetization measurements. The results confirm that aqueous suspensions of PEGylated SPIONs are stabilized by steric hindrance over a wide pH range between pH 4 and 10. Furthermore, the fact that the nanoparticle surface is nearly neutral is in agreement with immunological stealthiness expected for the future biomedical applications in?vivo.     

Inhibition of 3‐D Tumor Spheroids by Timed‐Released Hydrophilic and Hydrophobic Drugs from Multilayered Polymeric Microparticles

First‐line cancer chemotherapy necessitates high parenteral dosage and repeated dosing of a combination of drugs over a prolonged period. Current commercially available chemotherapeutic agents, such as Doxil and Taxol, are only capable of delivering single drug in a bolus dose. The aim of this study is to develop dual‐drug‐loaded, multilayered microparticles and to investigate their antitumor efficacy compared with single‐drug‐loaded particles. Results show hydrophilic doxorubicin HCl (DOX) and hydrophobic paclitaxel (PTX) localized in the poly(dl ‐lactic‐co‐glycolic acid, 50:50) (PLGA) shell and in the poly(l ‐lactic acid) (PLLA) core, respectively. The introduction of poly[(1,6‐bis‐carboxyphenoxy) hexane] (PCPH) into PLGA/PLLA microparticles causes PTX to be localized in the PLLA and PCPH mid‐layers, whereas DOX is found in both the PLGA shell and core. PLGA/PLLA/PCPH microparticles with denser shells allow better control of DOX release. A delayed release of PTX is observed with the addition of PCPH. Three‐dimensional MCF‐7 spheroid studies demonstrate that controlled co‐delivery of DOX and PTX from multilayered microparticles produces a greater reduction in spheroid growth rate compared with single‐drug‐loaded particles. This study provides mechanistic insights into how distinctive structure of multilayered microparticles can be designed to modulate the release profiles of anticancer drugs, and how co‐delivery can potentially provide better antitumor response.     

Drug‐Loaded Multifunctional Nanoparticles Targeted to the Endocardial Layer of the Injured Heart Modulate Hypertrophic Signaling

Ischemic heart disease is the leading cause of death globally. Severe myocardial ischemia results in a massive loss of myocytes and acute myocardial infarction, the endocardium being the most vulnerable region. At present, current therapeutic lines only ameliorate modestly the quality of life of these patients. Here, an engineered nanocarrier is reported for targeted drug delivery into the endocardial layer of the left ventricle for cardiac repair. Biodegradable porous silicon (PSi) nanoparticles are functionalized with atrial natriuretic peptide (ANP), which is known to be expressed predominantly in the endocardium of the failing heart. The ANP–PSi nanoparticles exhibit improved colloidal stability and enhanced cellular interactions with cardiomyocytes and non‐myocytes with minimal toxicity. After confirmation of good retention of the radioisotope 111‐Indium in relevant physiological buffers over 4 h, in vivo single‐photon emission computed tomography (SPECT/CT) imaging and autoradiography demonstrate increased accumulation of ANP–PSi nanoparticles in the ischemic heart, particularly in the endocardial layer of the left ventricle. Moreover, ANP–PSi nanoparticles loaded with a novel cardioprotective small molecule attenuate hypertrophic signaling in the endocardium, demonstrating cardioprotective potential. These results provide unique insights into the development of nanotherapies targeted to the injured region of the myocardium.     

Redox and pH Dual Responsive Polymer Based Nanoparticles for In Vivo Drug Delivery

Responsive nanomaterials have emerged as promising candidates as drug delivery vehicles in order to address biomedical diseases such as cancer. In this work, polymer‐based responsive nanoparticles prepared by a supramolecular approach are loaded with doxorubicin (DOX) for the cancer therapy. The nanoparticles contain disulfide bonds within the polymer network, allowing the release of the DOX payload in a reducing environment within the endoplasm of cancer cells. In addition, the loaded drug can also be released under acidic environment. In vitro anticancer studies using redox and pH dual responsive nanoparticles show excellent performance in inducing cell death and apoptosis. Zebrafish larvae treated with DOX‐loaded nanoparticles exhibit an improved viability as compared with the cases treated with free DOX by the end of a 3 d treatment. Confocal imaging is utilized to provide the daily assessment of tumor size on zebrafish larva models treated with DOX‐loaded nanoparticles, presenting sustainable reduction of tumor. This work demonstrates the development of functional nanoparticles with dual responsive properties for both in vitro and in vivo drug delivery in the cancer therapy.     

One‐Step Fabrication of Triple‐Layered Polymeric Microparticles with Layer Localization of Drugs as a Novel Drug‐Delivery System

Particulate systems have tremendous potential to achieve controlled release and targeted delivery of drugs. However, conventional single‐layered particles have several inherent limitations, including initial burst release, the inability to provide zero‐order release, and a lack of time‐delayed or pulsatile release of therapeutic agents. Multilayered particles have the potential to overcome these disadvantages. Herein, it is shown how triple‐layered polymeric microparticles can be fabricated through a simple, economical, reliable, and versatile one‐step solvent evaporation technique. Particle morphologies and layer configurations are determined by scanning electron microscopy, polymer dissolution tests, and Raman mapping. Key fabrication parameters that affect the formation of triple‐layered polymeric microparticles comprising poly(DL ‐lactide‐co‐glycolide) (50:50), poly(L ‐lactide), and poly(ethylene‐co‐vinyl acetate) (40 wt% vinyl acetate) are discussed, along with their formation mechanisms. Layer thickness and the configurations of these microparticles are altered by changing the polymer mass ratios. Finally, it is shown that drugs can be localized in specific layers of the microparticles. This fabrication process can therefore be used to tailor microparticle designs, thus allowing such “designer” particulate drug‐delivery systems to function across a wide range of applications.     

Shedding Light on Metal‐Based Nanoparticles in Zebrafish by Computed Tomography with Micrometer Resolution

Metal‐based nanoparticles are clinically used for diagnostic and therapeutic applications. After parenteral administration, they will distribute throughout different organs. Quantification of their distribution within tissues in the 3D space, however, remains a challenge owing to the small particle diameter. In this study, synchrotron radiation‐based hard X‐ray tomography (SRμCT) in absorption and phase contrast modes is evaluated for the localization of superparamagnetic iron oxide nanoparticles (SPIONs) in soft tissues based on their electron density and X‐ray attenuation. Biodistribution of SPIONs is studied using zebrafish embryos as a vertebrate screening model. This label‐free approach gives rise to an isotropic, 3D, direct space visualization of the entire 2.5 mm‐long animal with a spatial resolution of around 2 µm. High resolution image stacks are available on a dedicated internet page ( http://zebrafish.pharma-te.ch ). X‐ray tomography is combined with physico‐chemical characterization and cellular uptake studies to confirm the safety and effectiveness of protective SPION coatings. It is demonstrated that SRμCT provides unprecedented insights into the zebrafish embryo anatomy and tissue distribution of label‐free metal oxide nanoparticles.