We report on the use of dopamine (DA) as a robust molecular anchor to link functional molecules to the iron oxide shell of magnetic nanoparticles. Using nitrilotriacetic acid (NTA) as the functional molecule, we created a system with an M/Fe2O3-DA-NTA (M = Co or SmCo5.2) nanostructure, which possesses high stability and specificity for separating histidine-tagged proteins. The well-established biocompatibility of iron oxide and the robust covalent bonds between DA and Fe2O3 render this strategy attractive for constructing biofunctional magnetic nanoparticles containing iron oxide.

Recent successful syntheses of monodispersed magnetic nanoparticles have offered a unique opportunity to control and probe biological interactions using magnetic force. This paper highlights a general strategy to generate biofunctional magnetic nanoparticles, illustrates applications for these nanoparticles in protein separation and pathogen detection, and analyzes the high sensitivity and high selectivity achieved by this system.

Using Nalpha,Nalpha-bis(carboxymethyl)lysine to react with FePt magnetic nanoparticles, we synthesized the FePt-NTA conjugate, which immobilizes Ni2+ ions and selectively binds to histidine-tagged proteins at concentration as low as 0.5 pM. This simple system serves as a useful alternative to existing protocols for protein separation and also acts as a versatile agent for transporting and anchoring proteins.

Self-assembly, a fundamental process at all scales, [1] plays a vital role in nature and provides an important guidance for design and fabrication of functional materials. [2] Particularly, self-assembly provides an attractive and practical methodology for creating artificial nanostructures that promise broad impacts and applications in the emerging field of nanoscience. For example, self-assembled nanoparticles can lead to novel optical materials [3] and high-density magnetic recording media; [4] self-assembled monolayers [5] have enabled nanometer thickness organic films to be constructed on a variety of substrates for modeling biological surface to control the fate of cells, [6] building molecular electronic devices, [7] developing nanolithography, [8] and generating nanostructures for biomedical diagnostics; [9] and the self-assembly of oligopeptides [10,11] and other organic molecules [12] has resulted in nanofibers as the functional matrices of hydrogels that find possible applications in tissue engineering, [10,13] inhibitor screening, [14] and wound healing. [15] Although these works reflect the exciting and important development of self-assembled nanostructures in a non-biological arena or extracellular settings, intracellular creation of artificial nanostructures remains less explored and its subsequent biological effects largely unknown despite of its potential significances and applications.To explore intracellular artificial nanostructures is significant for several reasons. First, self-assembled nanostructures (e.g., cell membranes, strands of nucleic acids, actin filaments) prevail in living cells and are indispensable for critical cellular functions (e.g., as structural motifs for maintaining integrity of cells, as effective storages for keeping genetic information, and as active devices for regulating numerous cellular processes), therefore intracellular artificial nanostructures provide an attractive and effective strategy from perturbing the cellular activities to managing the behaviors of cells. Second, many diseases are related to mishaps in cellular nanostructures (e.g., mismatch of base pairs, formation of b-amyloid, and misfolding of proteins), hence intracellular artificial nanostructures offers a versatile and accessible platform for mimicking, modeling, and understanding the mechanism of diseases. Third, spectacular advances in molecular cell biology (i.e., the study of biological process at the molecular level) during the last five decades have led to new insights into the evolution of life forms, and now there is a need to correlate biological process beyond molecule level and to understand structure and dynamics as a system (i.e., system biology). Self-assembled intracellular artificial structures at the nanoscale lend a convenient means to examine the structure and dynamics of cellular functions and to allow previously unconnected domains of knowledge to be understood at new levels of complexity.Intracellular artificial nanostructures can result from different methodologies, ...

We report on the use of bisphosphonate to functionalize Fe3O4 magnetic nanoparticles via dopamine (DA) linkage. Using tetraethyl-3-aminopropane-1,1-bisphosphonate (BP) as the functional molecule, we created a system with an Fe3O4-DA-BP nanostructure, which possesses high specificity for removing uranyl ions from water or blood. This work demonstrates that magnetic nanoparticles, combined with specific receptor-ligand interactions, promise a sensitive and rapid platform for the detection, recovery, and decorporation of metal toxins from biological environment.

This paper reports the synthesis, characterization, and cellular uptake of the conjugate of porphyrin and iron oxide nanoparticles, which may lead to a bimodal anticancer agent that can be used in the combinational treatment of photodynamic therapy (PDT) and hyperthermia therapy (HT).

Two types of therapeutic agents, which have discrete yet complementary functions, self-assemble into nanofibers in water to formulate a new supramolecular hydrogel as a self-delivery biomaterial to reduce the toxicity of uranyl oxide at the wound sites.

Topical treatment using photodynamic therapy (PDT) for many types of skin cancers has largely been limited by the inability of existing photosensitizers to penetrate into the deep skin tissue. To overcome these problems, we developed a mesoporous nanovehicle with dual loading of photosensitizers and clinically relevant drugs for combination therapy, while utilizing microneedle technology to facilitate their penetration into deep skin tissue. Sub-50 nm photodynamically active mesoporous organosilica nanoparticles were synthesized with photosensitizers covalently bonded to the silica matrix, which dramatically increased the quantum yield and photostability of these photosensitizers. The mesopores of the nanoparticles were further loaded with small-molecule inhibitors, i.e., dabrafenib and trametinib, that target the hyperactive mitogen-activated protein kinase (MAPK) pathway for melanoma treatment. As-prepared empty nanovehicle was cytocompatible with normal skin cells in the dark, while NIR-irradiated drug-loaded nanovehicle showed a synergistic killing effect on skin cancer cells mainly through reactive oxygen species and caspase-activated apoptosis. The nanovehicle could significantly inhibit the proliferation of tumor cells in a 3D spheroid model in vitro. Porcine skin fluorescence imaging demonstrated that microneedles could facilitate the penetration of nanovehicle across the epidermis layer of skin to reach deep-seated melanoma sites. Tumor regression studies in a xenografted melanoma mouse model confirmed superior therapeutic efficacy of the nanovehicle through combinational PDT and targeted therapy.