Long-Term Fate of Magnetic Particles in Mice: A Comprehensive Study.

Safe application of nanoparticles in medicine requires full understanding of their pharmacokinetics including catabolism in the organism. However, information about nanoparticle degradation is still scanty due to difficulty of long-term measurements by invasive techniques. Here, we describe a magnetic spectral approach for in vivo monitoring of magnetic particle (MP) degradation. The method noninvasiveness has allowed performing of a broad comprehensive study of the 1-year fate of 17 types of iron oxide particles. We show a long-lasting influence of five parameters on the MP degradation half-life: dose, hydrodynamic size, ζ-potential, surface coating, and internal architecture. We observed a slowdown in MP biotransformation with an increase of the injected dose and faster degradation of the particles of a small hydrodynamic size. A comparison of six types of 100 nm particles coated by different hydrophilic polymer shells has shown that the slowest (t1/2 = 38 ± 6 days) and the fastest (t1/2 = 15 ± 4 days) degradations were achieved with a polyethylene glycol and polyglucuronic acid coatings, respectively. The most significant influence on the MP degradation was due to the internal architecture of the particles as the coverage of magnetic cores with a solid 39 nm polystyrene layer slowed down the half-life of the core-shell MPs from 48 days to more than 1 year. The revealed deeper insights into the particle degradation in vivo may facilitate rational design of nano- and microparticles with predictable long-term fate in vivo.

Hematite Nanoparticles from Unexpected Reaction of Ferrihydrite with Concentrated Acids for Biomedical Applications.

The development of synthetic ways to fabricate nanosized materials with a well-defined shape, narrow-sized distribution, and high stability is of great importance to a rapidly developing area of nanotechnology. Here, we report an unusual reaction between amorphous two-line ferrihydrite and concentrated sulfuric or other mineral and organic acids. Instead of the expected dissolution, we observed the formation of new narrow-distributed brick-red nanoparticles (NPs) of hematite. Different acids produce similar nanoparticles according to scanning (SEM) and transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray diffraction (XRD), infrared spectroscopy (FTIR), and energy-dispersive X-ray spectroscopy (EDX). The reaction demonstrates new possibilities for the synthesis of acid-resistant iron oxide nanoparticles and shows a novel pathway for the reaction of iron hydroxide with concentrated acids. The biomedical potential of the fabricated nanoparticles is demonstrated by the functionalization of the particles with polymers, fluorescent labels, and antibodies. Three different applications are demonstrated: i) specific targeting of the red blood cells, e.g., for red blood cell (RBC)-hitchhiking; ii) cancer cell targeting in vitro; iii) infrared ex vivo bioimaging. This novel synthesis route may be useful for the development of iron oxide materials for such specificity-demanding applications such as nanosensors, imaging, and therapy.

Nanoparticle Beacons: Supersensitive Smart Materials with On/Off-Switchable Affinity to Biomedical Targets.

Smart materials that can switch between different states under the influence of chemical triggers are highly demanded in biomedicine, where specific responsiveness to biomarkers is imperative for precise diagnostics and therapy. Superior selectivity of drug delivery to malignant cells may be achieved with the nanoagents that stay "inert" until "activation" by the characteristic profile of microenvironment cues (e.g., tumor metabolites, angiogenesis factors, microRNA/DNA, etc.). However, despite a wide variety and functional complexity of smart material designs, their real-life applications are hindered by very limited sensitivity to inputs. Here, we present ultrasensitive smart nanoagents with input-dependent On/Off switchable affinity to a biomedical target based on a combination of gold nanoparticles with low-energy polymer structures. In the proposed method, a nanoparticle-based agent is surface coated with a custom designed flexible polymer chain, which has an input-switchable structure that regulates accessibility of the terminal receptor for target binding. Implementation of the concept with a DNA-model of such polymer has yielded nanoagents that have input-dependent cell-targeting capabilities and responsiveness to as little as 30 fM of DNA input in 15 min lateral flow assay. Thus, we show that surface phenomena can augment nanoagents with capability for switchable affinity without compromising the sensitivity to inputs. The proposed approach is promising for development of next-generation theranostic agents and ultrasensitive nanosensors for point-of-care diagnostics.

Antibody-directed metal-organic framework nanoparticles for targeted drug delivery.

Nanosized metal-organic frameworks (nMOFs) have shown great promise as high-capacity carriers for a variety of applications. For biomedicine, numerous nMOFs have been proposed that can transport virtually any molecular drug, can finely tune their payload release profile, etc. However, perspectives of their applications for the targeted drug delivery remain relatively unclear. So far, only a few works have reported specific cell targeting by nMOFs exclusively through small ligands such as folic acid or RGD peptides. Here we show feasibility of targeted drug delivery to specific cancer cells in vitro with nMOFs functionalized with such universal tool as an antibody. We demonstrate ca. 120 nm magnetic core/MOFs shell nanoagents loaded with doxorubicin/daunorubicin and coupled with an antibody though a hydrophilic carbohydrate interface. We show that carboxymethyl-dextran coating of nMOFs allows extensive loading of the drug molecules (up to 15.7 mg/g), offers their sustained release in physiological media and preserves antibody specificity. Reliable performance of the agents is illustrated with trastuzumab-guided selective targeting and killing of HER2/neu-positive breast cancer cells in vitro. The approach expands the scope of nMOF applications and can serve as a platform for the development of potent theranostic nanoagents. STATEMENT OF SIGNIFICANCE: The unique combination of exceptional drug capacity and controlled release, biodegradability and low toxicity makes nanosized metal-organic frameworks (nMOFs) nearly ideal drug vehicles for various biomedical applications. Unfortunately, the prospective of nMOF applications for the targeted drug delivery is still unclear since only a few examples have been reported for nMOF cell targeting, exclusively for small ligands. In this work, we fill the important gap and demonstrate nanoagent that can specifically kill target cancer cells via drug delivery based on recognition of HER2/neu cell surface receptors by such universal and specific tool as antibodies. The proposed approach is universal and can be adapted for specific biomedical tasks using antibodies of any specificity and nMOFs of a various composition.

Synthesis of highly-specific stable nanocrystalline goethite-like hydrous ferric oxide nanoparticles for biomedical applications by simple precipitation method.

Exploration of novel types of iron oxide nanoparticles as well as novel versatile ways to prepare them in a controlled manner keeping in mind necessity of narrow size distributions and high colloidal and chemical stability is an important task for modern nanochemistry. Most of the procedures for preparation of nanocrystalline iron oxides require drastic conditions and complex mixtures of reagents, therefore there is a high demand for methods of synthesis of such nanoparticles (NPs) in mild conditions. In this study, we discovered a new way to prepare crystalline goethite-like hydrous ferric oxide (HFO) NPs by fast and simple precipitation procedure in aqueous media and probed modification strategies aimed at the development of modified HFO nanoparticles for biomedical applications, including express-diagnostics and specific cell targeting.

Smart materials on the way to theranostic nanorobots: Molecular machines and nanomotors, advanced biosensors, and intelligent vehicles for drug delivery.

BACKGROUND: Theranostics, a fusion of two key parts of modern medicine - diagnostics and therapy of the organism's disorders, promises to bring the efficacy of medical treatment to a fundamentally new level and to become the basis of personalized medicine. Extrapolating today's progress in the field of smart materials to the long-run prospect, we can imagine future intelligent agents capable of performing complex analysis of different physiological factors inside the living organism and implementing a built-in program thereby triggering a series of therapeutic actions. These agents, by analogy with their macroscopic counterparts, can be called nanorobots. It is quite obscure what these devices are going to look like but they will be more or less based on today's achievements in nanobiotechnology. SCOPE OF REVIEW: The present Review is an attempt to systematize highly diverse nanomaterials, which may potentially serve as modules for theranostic nanorobotics, e.g., nanomotors, sensing units, and payload carriers. MAJOR CONCLUSIONS: Biocomputing-based sensing, externally actuated or chemically "fueled" autonomous movement, swarm inter-agent communication behavior are just a few inspiring examples that nanobiotechnology can offer today for construction of truly intelligent drug delivery systems. GENERAL SIGNIFICANCE: The progress of smart nanomaterials toward fully autonomous drug delivery nanorobots is an exciting prospect for disease treatment. Synergistic combination of the available approaches and their further development may produce intelligent drugs of unmatched functionality.

Surface plasmon resonance as a tool for investigation of non-covalent nanoparticle interactions in heterogeneous self-assembly & disassembly systems.

Biomolecule-driven assembly of nanoparticles is a powerful and convenient approach for development of advanced nanosensors and theranostic agents with diverse "on-demand" composition and functionality. While a lot of research is being devoted to fabrication of such agents, the development of non-invasive analytical tools to monitor self-assembly/disassembly processes in real-time substantially lags behind. Here, we demonstrate the capabilities of localized surface plasmon resonance (SPR) phenomenon to study non-covalent interactions not just between plasmonic particles, but between gold nanoparticles (AuNP) and non-plasmonic ones. We show its potential to investigate assembly and performance of a novel type of advanced smart materials, namely, biocomputing agents. These agents, self-assembled from nanoparticles via biomolecular interfaces such as proteins, DNA, etc., can analyze presence of biomolecular inputs according to Boolean logic and undergo the input-induced disassembly in order to implement the proper output action. Using UV-Vis spectroscopy to monitor the assembly/disassembly processes of the basic YES-gate structure that consists of a polymer core particle with a multitude of associated gold nanoparticles, we found that the structure transformations are well-characterized by pronounced difference in SPR spectral band position (shifting up to 50nm). This SPR shift correlates remarkably well with biochemical estimation of the assembly/disassembly extent, and can provide valuable real-time kinetic analysis. We believe that the obtained data can be easily extended to other non-plasmonic nanoparticle systems having similar chemical and colloidal properties. SPR method can become a valuable addition to analytical toolbox for characterization of self-assembled smart nanosystems used in biosensing, imaging, controlled release and other applications.

Multiplex Biosensing Based on Highly Sensitive Magnetic Nanolabel Quantification: Rapid Detection of Botulinum Neurotoxins A, B, and E in Liquids.

We present a multiplex quantitative lateral flow (LF) assay for simultaneous on-site detection of botulinum neurotoxin (BoNT) types A, B, and E in complex matrixes, which is innovative by virtually no sacrifice in performance while transition from the single-plex assays and by characteristics on the level of laboratory quantitative methods. The novel approach to easy multiplexing is realized via joining an on-demand set of single-plex LF strips, which employ magnetic nanolabels, into a miniature cylinder cartridge that mimics LF strip during all assay stages. The cartridge is read out by an original portable multichannel reader based on the magnetic particle quantification technique. The developed reader offers the unmatched 60 zmol detection limit and 7-order linear dynamic range for volumetric registration of magnetic labels inside a cartridge of several millimeters in diameter regardless of its optical transparency. Each of the test strips, developed here as building blocks for the multiplex assay, can be used "as is" for autonomous quantitative single-plex detection with the same measuring setup, exhibiting the limits of detection (LOD) of 0.22, 0.11, and 0.32 ng/mL for BoNT-A, -B, and -E, respectively. The proposed multiplex assay has demonstrated the remarkably similar LOD values of 0.20, 0.12, 0.35 ng/mL under the same conditions. The multiplex assay performance was successfully validated by BoNT detection in milk and apple and orange juices. The developed methods can be extended to other proteins and used for rapid multianalyte tests for point-of-care in vitro diagnostics, food analysis, biosafety and environmental monitoring, forensics, and security, etc.