Activatable magnetic resonance nanosensor as a potential imaging agent for detecting and discriminating thrombosis

The early detection and accurate characterization of life-threatening diseases such as cardiovascular disease and cancer are critical to the design of treatment. Knowing whether or not a thrombus in a blood vessel is new (fresh) or old (constituted) is very important for physicians to decide a treatment protocol. We have designed smart MRI nano-sensors that can detect, sense and report the stage or progression of cardiovascular diseases such as thrombosis. The nanosensors were functionalized with fibrin-binding peptide to specifically target thrombus and were also labelled with fluorescent dye to enable optical imaging. We have demonstrated that our nanosensors were able to switch between the T1 and T2 signal depending on thrombus age or the presence or absence of thrombin at the thrombus site. The developed nanosensors appeared to be non-toxic when tested with Chinese Hamster Ovarian cells within the tested concentrations. The working principle demonstrated in this study can be applied to many other diseases such as cancer.

Novel iron oxide-cerium oxide core-shell nanoparticles as a potential theranostic material for ROS related inflammatory diseases

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are key signaling molecules that play an important role in the inflammation and progression of many diseases such as cardiovascular disease, especially atherosclerosis. ROS are in particular a significant factor in the development of rheumatoid arthritis and other autoimmune diseases such as allergies. In this study, novel Fe₃O₄/CeO₂ core-shell theranostic nanoparticles capable of reacting with ROS and of being detected by MRI were synthesized and thoroughly characterized. In vitro studies, such as measurement of cell uptake, magnetic resonance imaging, toxicity and ROS scavenging, were conducted. The results indicate that the novel Fe₃O₄/CeO₂ theranostic nanoparticles are effective for scavenging ROS and show excellent magnetic resonance (MR) imaging performance. These theranostic nanomaterials, therefore, show great potential for the treatment and diagnosis of ROS-related inflammatory diseases.

A unique 19F MRI agent for the tracking of non phagocytic cells in vivo

There is currently intense interest in new methods for understanding the fate of therapeutically-relevant cells, such as mesenchymal stem cells (MSCs). The absence of a confounding background signal and consequent unequivocal assignment makes 19F MRI one of the most attractive modalities for the tracking of injected cells in vivo. We describe here the synthesis of novel partly-fluorinated polymeric nanoparticles with small size and high fluorine content as MRI agents. The polymers, constructed from perfluoropolyether methacrylate (PFPEMA) and oligo(ethylene glycol) methacrylate (OEGMA) have favourable cell uptake profiles and excellent MRI performance. To facilitate cell studies the polymer was further conjugated with a fluorescent dye creating a dual-modal imaging agent. The efficacy of labelling of MSCs was assessed using 19F NMR, flow cytometry and confocal microscopy. The labelling efficiency of 2.6 ± 0.1 × 1012 19F atoms per cell, and viability of >90% demonstrates high uptake and good tolerance by the cells. This loading translates to a minimum 19F MRI detection sensitivity of ∼7.4 × 103 cells per voxel. Importantly, preliminary in vivo data demonstrate that labelled cells can be readily detected within a short acquisition scan period (12 minutes). Hence, these copolymers show outstanding potential for 19F MRI cellular tracking and for quantification of non-phagocytic and therapeutically-relevant cells in vivo.

Overcoming Surfactant-Induced Morphology Instability of Noncrosslinked Diblock Copolymer Nano-Objects Obtained by RAFT Emulsion Polymerization

RAFT emulsion polymerization techniques including polymerization-induced self-assembly (PISA) and temperature-induced morphological transformation (TIMT) are widely used to produce noncrosslinked nano-objects with various morphologies. However, the worm, vesicle and lamellar morphologies produced by these techniques typically cannot tolerate the presence of added surfactants, thus limiting their potential applications. Herein we report the surfactant tolerance of noncrosslinked worms, vesicles, and lamellae prepared by RAFT emulsion polymerizations using poly(di(ethylene glycol) ethyl ether methacrylate-co-N-(2-hydroxypropyl) methacrylamide) (P(DEGMA-co-HPMA)) as a macromolecular chain transfer agent (macro-CTA). Significantly, these P(DEGMA-co-HPMA) nanoparticles are highly stable in concentrated solutions of surfactants (e.g., sodium dodecyl sulfate (SDS)). We also demonstrate that the surfactant tolerance is related to the limited binding of SDS to the main-chain of the P(DEGMA-co-HPMA) macro-CTA constituting the particle shell. This work provides new insight into the interactions between surfactants and thermoresponsive copolymers and expands the scope of RAFT emulsion polymerization techniques for the preparation of noncrosslinked and surfactant-tolerant nanomaterials.

3D shape change of multi-responsive hydrogels based on a light-programmed gradient in volume phase transition

We present a new type of anisotropic oligo(ethylene glycol) methacrylate hydrogel with multi-responsive and programmable 3D deformation behaviour.

A two-step synthesis for preparing metal microcapsules with a biodegradable polymer substrate

Novel method of producing metal microcapsules, using nanoparticles as the stabiliser, allows better control of nanoparticle distribution thus optimisation of metal shells.

Controlled synthesis of up-conversion luminescent Gd/Tm-MOFs for pH-responsive drug delivery and UCL/MRI dual-modal imaging

Using a facile one-step hydrothermal method, a series of metal–organic frameworks containing Gd/Tm (Gd/Tm-MOFs) were prepared successfully.

Controllable synthesis of a novel magnetic core-shell nanoparticle for dual-modal imaging and pH-responsive drug delivery

In this study, novel magnetic core-shell nanoparticles Fe₃O₄@La-BTC/GO have been synthesized by the layer-by-layer self-assembly (LBL) method and further modified by attachment of amino-modified PEG chains. The nanoparticles were thoroughly characterized by x-ray diffraction, FTIR, scanning electron microscopy and transmission electron microscopy. The core-shell structure was shown to be controlled by the LBL method. The drug loading of doxorubicin (DOX) within the Fe₃O₄@La-BTC/GO-PEG nanoparticles with different numbers of deposited layers was investigated. It was found that DOX loading increased with increasing number of metal organic framework coating layers, indicating that the drug loading can be controlled through the controllable LBL method. Cytotoxicity assays indicated that the Fe₃O₄@La-BTC/GO-PEG nanoparticles were biocompatible. The DOX was released rapidly at pH 3.8 and pH 5.8, but at pH 7.4 the rate and extent of release was greatly attenuated. The nanoparticles therefore demonstrate an excellent pH-triggered drug release. In addition, the particles could be tracked by magnetic resonance imaging (MRI) and fluorescence optical imaging (FOI). A clear dose-dependent contrast enhancement in T ₂-weighted MR images and fluorescence images indicate the potential of these nanoparticles as dual-mode MRI/FOI contrast agents.

Nanoparticle-mediated local depletion of tumour-associated platelets disrupts vascular barriers and augments drug accumulation in tumours

Limited intratumoural perfusion and nanoparticle retention remain major bottlenecks for the delivery of nanoparticle therapeutics into tumours. Here, we show that polymer-lipid-peptide nanoparticles delivering the antiplatelet antibody R300 and the chemotherapeutic agent doxorubicin can locally deplete tumour-associated platelets, thereby enhancing vascular permeability and augmenting the accumulation of the nanoparticles in tumours. R300 is specifically released in the tumour on cleavage of the lipid-peptide shell of the nanoparticles by matrix metalloprotease 2, which is commonly overexpressed in tumour vascular endothelia and stroma, thus facilitating vascular breaches that enhance tumour permeability. We also show that this strategy leads to substantial tumour regression and metastasis inhibition in mice.

Hydrogels with Lotus Leaf Topography: Investigating Surface Properties and Cell Adhesion

The interactions of cells with the surface of materials is known to be influenced by a range of factors that include chemistry and roughness; however, it is often difficult to probe these factors individually without also changing the others. Here we investigate the role of roughness on cell adhesion while maintaining the same underlying chemistry. This was achieved by using a polymerization in mold technique to prepare poly(hydroxymethyl methacrylate) hydrogels with either a flat topography or a topography that replicated the microscale features of lotus leaves. These materials were then assessed for cell adhesion, and atomic force microscopy and contact angle analysis were then used to probe the physical reasons for the differing behavior in relation to cell adhesion.

Synthesis of aliphatic polycarbonates with a tuneable thermal response

The synthesis of aliphatic polycarbonates with a tuneable thermal-response is reported by a ‘click-and mix’ approach.

Polymeric 19F MRI agents responsive to reactive oxygen species

Medical imaging agents that can report on the biological state are attracting increasing interest.

Aqueous solution behaviour of novel water-soluble amphiphilic copolymers with elevated hydrophobic unit content

The synthesis and aqueous solution behaviour of water-soluble copolymers poly(OEGMA-stat-styrene)-b-PDMAPMA with a relatively high content of styrene units were explored.

Electrospinning and mechanical properties of P(TMC-co-LLA) elastomers

P(TMC-co-LLA) elastomers have shown great potential for various biomaterial and tissue engineering applications.

Functional magnetic porous silica for T 1-T 2 dual-modal magnetic resonance imaging and pH-responsive drug delivery of basic drugs

A smart magnetic-targeting drug carrier γ-Fe₂O₃@p-silica comprising a γ-Fe₂O₃ core and porous shell has been prepared and characterized. The particles have a uniform size of about 60 nm, and a porous shell of thickness 3 nm. Abundant hydroxyl groups and a large surface area enabled the γ-Fe₂O₃@p-silica to be readily loaded with a large payload of the basic model drug rhodamine B (RB) (up to 73 mg g^-1). Cytotoxicity assays of the γ-Fe₂O₃@p-silica particles indicated that the particles were biocompatible and suitable for carrying drugs. It was found that the RB was released rapidly at pH 5.5 but at pH 7.4 the rate and extent of release was greatly attenuated. The particles therefore demonstrate an excellent pH-triggered drug release. In addition, the γ-Fe₂O₃@p-silica particles could be tracked by magnetic resonance imaging (MRI). A clear dose-dependent contrast enhancement in both T ₁-weighted and T ₂-weighted MR images indicated the potential of the γ-Fe₂O₃@p-silica particles to act as dual-mode T ₁ and T ₂ MRI contrast agents.