Theranostic nanoparticles engineered for clinic and pharmaceutics

Nanomedicine is the manipulation of human biological systems at the molecular level using nanoscale or nanostructured materials. Because nanoscale materials interact effectively with biological systems, the use of nanodiagnostics and nanotherapeutics may overcome many intractable health challenges. A variety of nanoparticles have been designed with modifiable functional surfaces and bioactive cores. The engineering of nanoparticles can result in several advantageous therapeutic and diagnostic properties including enhanced permeation and retention in the circulatory system, specific delivery of drugs to target sites, highly-efficient gene transfection, and enhanced medical imaging. These nanoscale materials offer the opportunity to detect chronic diseases early and to monitor the therapeutic effects of nanoformulated drugs used in the clinic. Many of these novel nanoparticles contain both drug(s) and imaging agent(s) within an individual nanoparticle for simultaneous disease diagnosis and therapy. Further integration of therapeutic compounds with diagnostic agents into theranostic nanoparticles would be highly beneficial. However, the unique physiochemical properties that make nanomaterials attractive for therapy and diagnosis may be also associated with potential health hazards. Our research has demonstrated that the biological response to nanomaterials is related to many factors including exposure levels, systemic accumulation and excretion profiles, tissue and organ distribution, and the age of the test subject. Therefore, when engineering new nanomaterials for clinical use, researchers need to consider these factors to minimize toxicity of nanoparticles in these applications. We have fabricated and evaluated nanomaterials such as cationic amphiphilic polymers and metallofullerenes that demonstrate both high efficiency and low toxicity in gene therapy and/or chemotherapy. In this Account, we describe the development of theranostic nanomaterials with low toxicity and illustrate their potential use as novel nanomedicines in translational research.     

Monodisperse Gold Nanoparticles: A Review on Synthesis and Their Application in Modern Medicine

Gold nanoparticles (AuNPs) are becoming increasingly popular as drug carriers due to their unique properties such as size tenability, multivalency, low toxicity and biocompatibility. AuNPs have physical features that distinguish them from bulk materials, small molecules and other nanoscale particles. Their unique combination of characteristics is just now being fully realized in various biomedical applications. In this review, we focus on the research accomplishments and new opportunities in this field, and we describe the rising developments in the use of monodisperse AuNPs for diagnostic and therapeutic applications. This study addresses the key principles and the most recent published data, focusing on monodisperse AuNP synthesis, surface modifications, and future theranostic applications. Moving forward, we also consider the possible development of functionalized monodisperse AuNPs for theranostic applications based on these efforts. We anticipate that as research advances, flexible AuNPs will become a crucial platform for medical applications.     

Mechanized silica nanoparticles: a new frontier in theranostic nanomedicine

Medicine can benefit significantly from advances in nanotechnology because nanoscale assemblies promise to improve on previously established therapeutic and diagnostic regimes. Over the past decade, the use of delivery platforms has attracted attention as researchers shift their focus toward new ways to deliver therapeutic and/or diagnostic agents and away from the development of new drug candidates. Metaphorically, the use of delivery platforms in medicine can be viewed as the "bow-and-arrow" approach, where the drugs are the arrows and the delivery vehicles are the bows. Even if one possesses the best arrows that money can buy, they will not be useful if one does not have the appropriate bow to deliver the arrows to their intended location. Currently, many strategies exist for the delivery of bioactive agents within living tissue. Polymers, dendrimers, micelles, vesicles, and nanoparticles have all been investigated for their use as possible delivery vehicles. With the growth of nanomedicine, one can envisage the possibility of fabricating a theranostic vector that could release powerful therapeutics and diagnostic markers simultaneously and selectively to diseased tissue. In our design of more robust theranostic delivery systems, we have focused our attention on using mesoporous silica nanoparticles (SNPs). The payload "cargo" molecules can be stored within this robust domain, which is stable to a wide range of chemical conditions. This stability allows SNPs to be functionalized with stimulus-responsive mechanically interlocked molecules (MIMs) in the shape of bistable rotaxanes and psuedorotaxanes to yield mechanized silica nanoparticles (MSNPs). In this Account, we chronicle the evolution of various MSNPs, which came about as a result of our decade-long collaboration, and discuss advances in the synthesis of novel hybrid SNPs and the various MIMs which have been attached to their surfaces. These MIMs can be designed in such a way that they either change shape or shed off some of their parts in response to a specific stimulus, such as changes in redox potential, alterations in pH, irradiation with light, or the application of an oscillating magnetic field, allowing a theranostic payload to be released from the nanopores to a precise location at the appropiate time. We have also shown that these integrated systems can operate not only within cells, but also in live animals in response to pre-existing biological triggers. Recognizing that the theranostics of the future could offer a fresh approach to the treatment of degenerative diseases including cancer, we aim to start moving out of the chemical domain and into the biological one. Some MSNPs are already being tested in biological systems.     

Theranostic nanoshells: from probe design to imaging and treatment of cancer

Recent advances in nanoscience and biomedicine have expanded our ability to design and construct multifunctional nanoparticles that combine targeting, therapeutic, and diagnostic functions within a single nanoscale complex. The theranostic capabilities of gold nanoshells, spherical nanoparticles with silica cores and gold shells, have attracted tremendous attention over the past decade as nanoshells have emerged as a promising tool for cancer therapy and bioimaging enhancement. This Account examines the design and synthesis of nanoshell-based theranostic agents, their plasmon-derived optical properties, and their corresponding applications. We discuss the design and preparation of nanoshell complexes and their ability to enhance the photoluminescence of fluorophores while maintaining their properties as MR contrast agents. In this Account, we discuss the underlying physical principles that contribute to the photothermal response of nanoshells. We then elucidate the photophysical processes that induce nanoshells to enhance the fluorescence of weak near-infrared fluorophores. Nanoshells illuminated with resonant light are either strong optical absorbers or scatterers, properties that give rise to their unique capabilities. These physical processes have been harnessed to visualize and eliminate cancer cells. We describe the application of nanoshells as a contrast agent for optical coherence tomography of breast carcinoma cells in vivo. Our recent studies examine nanoshells as a multimodal theranostic probe, using these nanoparticles for near-infrared fluorescence and magnetic resonance imaging (MRI) and for the photothermal ablation of cancer cells. Multimodal nanoshells show theranostic potential for imaging subcutaneous breast cancer tumors in animal models and the distribution of tumors in various tissues. Nanoshells also show promise as light-triggered gene therapy vectors, adding temporal control to the spatial control characteristic of nanoparticle-based gene therapy approaches. We describe the fabrication of DNA-conjugated nanoshell complexes and compare the efficiency of light-induced and thermally-induced release of DNA. Double-stranded DNA nanoshells also provide a way to deliver small molecules into cells: we describe the delivery and light-triggered release of DAPI (4',6-diamidino-2-phenylindole), a dye molecule used to stain DNA in the nuclei of cells.     

Application of Asymmetrical Flow Field-Flow Fractionation for Characterizing the Size and Drug Release Kinetics of Theranostic Lipid Nanovesicles

Liposome size and in vitro release of the active substance belong to critical quality attributes of liposomal carriers. Here, we apply asymmetric flow field-flow fractionation (AF4) to characterize theranostic liposomes prepared by thin lipid film hydration/extrusion or microfluidics. The vesicles’ size was derived from multi-angle laser light scattering following fractionation (AF4) and compared to sizes derived from dynamic light scattering measurements. Additionally, we adapted a previously developed AF4 method to study zinc phthalocyanine (ZnPc) release/transfer from theranostic liposomes. To this end, theranostic liposomes were incubated with large acceptor liposomes serving as a sink (mimicking biological sinks) and were subsequently separated by AF4. During incubation, ZnPc was transferred from donor to acceptor fraction until reaching equilibrium. The process followed first-order kinetics with half-lives between 119.5–277.3 min, depending on the formulation. The release mechanism was postulated to represent a combination of Fickian diffusion and liposome relaxation. The rate constant of the transfer was proportional to the liposome size and inversely proportional to the ZnPc/POPC molar ratio. Our results confirm the usefulness of AF4 based method to study in vitro release/transfer of lipophilic payload, which may be useful to estimate the unwanted loss of drug from the liposomal carrier in vivo.     

Smart Lipid–Polysaccharide Nanoparticles for Targeted Delivery of Doxorubicin to Breast Cancer Cells

In this study, actively-targeted (CD44-receptors) and dual stimuli (pH/redox)-responsive lipid–polymer nanoparticles were proposed as a delivery vehicle of doxorubicin hydrochloride in triple negative breast cancer cell lines. A phosphatidylcholine lipid film was hydrated with a solution of oxidized hyaluronic acid and doxorubicin, chosen as model drug, followed by a crosslinking reaction with cystamine hydrochloride. The obtained spherical nanoparticles (mean diameter of 30 nm) were found to be efficiently internalized in cancer cells by a receptor-mediated endocytosis process, and to modulate the drug release depending on the pH and redox potential of the surrounding medium. In vitro cytotoxicity assays demonstrated the safety and efficacy of the nanoparticles in enhancing the cytotoxic effect of the free anticancer drug, with the IC₅₀ values being reduced by two and three times in MDA-MB-468 and MDA-MB-231, respectively. The combination of self-assembled phospholipid molecules with a polysaccharide counterpart acting as receptor ligand, and stimuli-responsive chemical moieties, was carried out on smart multifunctional nanoparticles able to actively target breast cancer cells and improve the in vitro anticancer activity of doxorubicin.     

Molecular imaging with theranostic nanoparticles

Nanoparticles (NPs) offer diagnostic and therapeutic capabilities not available with small molecules or microscale tools. As the field of molecular imaging has emerged from the blending of molecular biology with medical imaging, NP imaging is increasingly common for both therapeutic and diagnostic applications. The term theranostic describes technology with concurrent and complementary diagnostic and therapeutic capabilities. Although NPs have been FDA-approved for clinical use as transport vehicles for nearly 15 years, full translation of their theranostic potential is incomplete. However, NPs have shown remarkable success in the areas of drug delivery and magnetic resonance imaging. Emerging applications include image-guided resection, optical/photoacoustic imaging in vivo, contrast-enhanced ultrasound, and thermoablative therapy. Diagnosis with NPs in molecular imaging involves the correlation of the signal with a phenotype. The location and intensity of NP signals emanating from a living subject indicate the disease area's size, stage, and biochemical signature. Therapy with NPs uses the image for resection or delivery of a small molecule or RNA therapeutic. Ablation of the affected area is also possible via heat or radioactivity. The ideal theranostic NP includes several features: (1) it selectively and rapidly accumulates in diseased tissue; (2) it reports biochemical and morphological characteristics of the area; (3) it delivers an effective therapeutic; and (4) it is safe and biodegrades with nontoxic byproducts. Such a system contains a central imaging core surrounded by small molecule therapeutics. The system targets via ligands such as IgG and is protected from immune scavengers by a cloak of protective polymer. Although no NP has achieved all of the above criteria, many NPs possess one or more of these features. While the most clinically translatable NPs have been used in the field of magnetic resonance imaging, other types in development are quickly becoming more biocompatible through methods that modify their toxicity and biodistribution profiles. In this Account, we describe diagnostic imaging and therapeutic uses of NPs. We propose and offer examples of five primary types of nanoparticles with concurrent diagnostic and therapeutic uses.     

Conjugation of the 9-kDa Isoform of Granulysin with Liposomes Potentiates Its Cytotoxicity

Nine kDa granulysin (GRNLY) is a human cytolytic protein secreted by cytotoxic T lymphocytes (CTL) and NK cells of the immune system whose demonstrated physiological function is the elimination of bacteria and parasites. In previous studies by our group, the anti-tumor capacity of recombinant granulysin was demonstrated, both in vitro and in vivo. In the present work, we developed lipid nanoparticles whose surfaces can bind recombinant granulysin through the formation of a complex of coordination between the histidine tail of the protein and Ni²⁺ provided by a chelating lipid in the liposome composition and termed them LUV-GRNLY, for granulysin-bound large unilamellar vesicles. The objective of this formulation is to increase the granulysin concentration at the site of contact with the target cell and to increase the cytotoxicity of the administered dose. The results obtained in this work indicate that recombinant granulysin binds to the surface of the liposome with high efficiency and that its cytotoxicity is significantly increased when it is in association with liposomes. In addition, it has been demonstrated that the main mechanism of death induced by both granulysin and LUV-GRNLY is apoptosis. Jurkat-shBak cells are resistant to GRNLY and also to LUV-GRNLY, showing that LUV-GRNLY uses the mitochondrial apoptotic pathway to induce cell death. On the other hand, we show that LUV-GRNLY induces the expression of the pro-apoptotic members of the Bcl-2 family Bim and especially PUMA, although it also induced the expression of anti-apoptotic Bcl-x_L. In conclusion, we demonstrate that binding of GRNLY to the surfaces of liposomes clearly augments its cytotoxic potential, with cell death executed mainly by the mitochondrial apoptotic pathway.     

Tailored-Made Polydopamine Nanoparticles to Induce Ferroptosis in Breast Cancer Cells in Combination with Chemotherapy

Ferroptosis is gaining followers as mechanism of selective killing cancer cells in a non-apoptotic manner, and novel nanosystems capable of inducing this iron-dependent death are being increasingly developed. Among them, polydopamine nanoparticles (PDA NPs) are arousing interest, since they have great capability of chelating iron. In this work, PDA NPs were loaded with Fe³⁺ at different pH values to assess the importance that the pH may have in determining their therapeutic activity and selectivity. In addition, doxorubicin was also loaded to the nanoparticles to achieve a synergist effect. The in vitro assays that were performed with the BT474 and HS5 cell lines showed that, when Fe³⁺ was adsorbed in PDA NPs at pH values close to which Fe(OH)₃ begins to be formed, these nanoparticles had greater antitumor activity and selectivity despite having chelated a smaller amount of Fe³⁺. Otherwise, it was demonstrated that Fe³⁺ could be released in the late endo/lysosomes thanks to their acidic pH and their Ca²⁺ content, and that when Fe³⁺ was co-transported with doxorubicin, the therapeutic activity of PDA NPs was enhanced. Thus, reported PDA NPs loaded with both Fe³⁺ and doxorubicin may constitute a good approach to target breast tumors.     

One-pot synthesis of sustained-released doxorubicin silica nanoparticles for aptamer targeted delivery to tumor cells

Site-specific delivery of drugs can significantly reduce drug toxicity and increase the therapeutic effect. Here, we report a one-pot synthesis of doxorubicin-doped silica nanoparticles (Dox/SiNPs) by using sodium fluoride (NaF) catalyzed hydrolysis of tetraethyl orthosilicate in a water-in-oil microemulsion. Through further surface chemical modification, carboxyl-terminated Dox/SiNPs (COOH-Dox/SiNPs) exhibiting high drug entrapment efficiency, strong fluorescence and long sustained release are obtained. Cell toxicity tests demonstrate that the COOH-Dox/SiNPs kill tumor cells effectively, while pure COOH-SiNPs are nontoxic. An aptamer is further conjugated to the nanoparticles for delivering loaded Dox to target cells. It is demonstrated that Dox/SiNPs modified with the aptamer sgc8c (sgc8c-Dox/SiNPs) could deliver loaded doxorubicin to CCRF-CEM cells with high specificity and excellent efficiency. Furthermore, ex vivo imaging studies show that the COOH-Dox/SiNPs are able to accumulate highly in the tumor areas, thanks to the enhanced permeability and retention (EPR) effects. Our data suggest that the sgc8c-Dox/SiNPs may be a useful new tumor therapy system.     

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.     

A Nano-Emulsion Platform Functionalized with a Fully Human scFv-Fc Antibody for Atheroma Targeting: Towards a Theranostic Approach to Atherosclerosis

Atherosclerosis is at the onset of the cardiovascular diseases that are among the leading causes of death worldwide. Currently, high-risk plaques, also called vulnerable atheromatous plaques, remain often undiagnosed until the occurrence of severe complications, such as stroke or myocardial infarction. Molecular imaging agents that target high-risk atheromatous lesions could greatly improve the diagnosis of atherosclerosis by identifying sites of high disease activity. Moreover, a “theranostic approach” that combines molecular imaging agents (for diagnosis) and therapeutic molecules would be of great value for the local management of atheromatous plaques. The aim of this study was to develop and characterize an innovative theranostic tool for atherosclerosis. We engineered oil-in-water nano-emulsions (NEs) loaded with superparamagnetic iron oxide (SPIO) nanoparticles for magnetic resonance imaging (MRI) purposes. Dynamic MRI showed that NE-SPIO nanoparticles decorated with a polyethylene glycol (PEG) layer reduced their liver uptake and extended their half-life. Next, the NE-SPIO-PEG formulation was functionalized with a fully human scFv-Fc antibody (P3) recognizing galectin 3, an atherosclerosis biomarker. The P3-functionalized formulation targeted atheromatous plaques, as demonstrated in an immunohistochemistry analyses of mouse aorta and human artery sections and in an Apoe^−/− mouse model of atherosclerosis. Moreover, the formulation was loaded with SPIO nanoparticles and/or alpha-tocopherol to be used as a theranostic tool for atherosclerosis imaging (SPIO) and for delivery of drugs that reduce oxidation (here, alpha-tocopherol) in atheromatous plaques. This study paves the way to non-invasive targeted imaging of atherosclerosis and synergistic therapeutic applications.     

Responsive theranostic systems: integration of diagnostic imaging agents and responsive controlled release drug delivery carriers

For decades, researchers and medical professionals have aspired to develop mechanisms for noninvasive treatment and monitoring of pathological conditions within the human body. The emergence of nanotechnology has spawned new opportunities for novel drug delivery vehicles capable of concomitant detection, monitoring, and localized treatment of specific disease sites. In turn, researchers have endeavored to develop an imaging moiety that could be functionalized to seek out specific diseased conditions and could be monitored with conventional clinical imaging modalities. Such nanoscale detection systems have the potential to increase early detection of pathophysiological conditions because they can detect abnormal cells before they even develop into diseased tissue or tumors. Ideally, once the diseased cells are detected, clinicians would like to treat those cells simultaneously. This idea led to the concept of multifunctional carriers that could target, detect, and treat diseased cells. The term "theranostics" has been created to describe this promising area of research that focuses on the combination of diagnostic detection agents with therapeutic drug delivery carriers. Targeted theranostic nanocarriers offer an attractive improvement to disease treatment because of their ability to execute simultaneous functions at targeted diseased sites. Research efforts in the field of theranostics encompass a broad variety of drug delivery vehicles, imaging contrast agents, and targeting modalities for the development of an all-in-one, localized detection and treatment system. Nanotheranostic systems that utilize metallic or magnetic imaging nanoparticles can also be used as thermal therapeutic systems. This Account explores recent advances in the field of nanotheranostics and the various fundamental components of an effective theranostic carrier.     

Dextran-coated iron oxide nanoparticles: a versatile platform for targeted molecular imaging, molecular diagnostics, and therapy

Advances in our understanding of the genetic basis of disease susceptibility coupled with prominent successes for molecular targeted therapies have resulted in an emerging strategy of personalized medicine. This approach envisions risk stratification and therapeutic selection based on an individual's genetic makeup and physiologic state (the latter assessed through cellular or molecular phenotypes). Molecularly targeted nanoparticles can play a key role in this vision through noninvasive assessments of molecular processes and specific cell populations in vivo, sensitive molecular diagnostics, and targeted delivery of therapeutics. A superparamagnetic iron oxide nanoparticle with a cross-linked dextran coating, or CLIO, is a powerful and illustrative nanoparticle platform for these applications. These structures and their derivatives support diagnostic imaging by magnetic resonance (MRI), optical, and positron emission tomography (PET) modalities and constitute a versatile platform for conjugation to targeting ligands. A variety of conjugation methods exist to couple the dextran surface to different functional groups; in addition, a robust bioorthogonal [4 + 2] cycloaddition reaction between 1,2,4,5-tetrazene (Tz) and trans-cyclooctene (TCO) can conjugate nanoparticles to targeting ligands or label pretargeted cells. The ready availability of conjugation methods has given rise to the synthesis of libraries of small molecule modified nanoparticles, which can then be screened for nanoparticles with specificity for a specific cell type. Since most nanoparticles display their targeting ligands in a multivalent manner, a detailed understanding of the kinetics and affinity of a nanoparticle's interaction with its target (as determined by surface plasmon resonance) can yield functionally important insights into nanoparticle design. In this Account, we review applications of the CLIO platform in several areas relevant to the mission of personalized medicine. We demonstrate rapid and highly sensitive molecular profiling of cancer markers ex vivo, as part of detailed, individualized molecular phenotyping. The CLIO platform also facilitates targeted magnetic resonance and combined modality imaging (such as MR/PET/fluorescence/CT) to enable multiplexed measurement of molecular phenotypes in vivo for early diagnosis and disease classification. Finally, the targeted delivery of a photodynamic therapy agent as part of a theranostic nanoparticle successfully increased local cell toxicity and minimized systemic side effects.     

Polymeric vesicles: from drug carriers to nanoreactors and artificial organelles

One strategy in modern medicine is the development of new platforms that combine multifunctional compounds with stable, safe carriers in patient-oriented therapeutic strategies. The simultaneous detection and treatment of pathological events through interactions manipulated at the molecular level offer treatment strategies that can decrease side effects resulting from conventional therapeutic approaches. Several types of nanocarriers have been proposed for biomedical purposes, including inorganic nanoparticles, lipid aggregates, including liposomes, and synthetic polymeric systems, such as vesicles, micelles, or nanotubes. Polymeric vesicles--structures similar to lipid vesicles but created using synthetic block copolymers--represent an excellent candidate for new nanocarriers for medical applications. These structures are more stable than liposomes but retain their low immunogenicity. Significant efforts have been made to improve the size, membrane flexibility, and permeability of polymeric vesicles and to enhance their target specificity. The optimization of these properties will allow researchers to design smart compartments that can co-encapsulate sensitive molecules, such as RNA, enzymes, and proteins, and their membranes allow insertion of membrane proteins rather than simply serving as passive carriers. In this Account, we illustrate the advances that are shifting these molecular systems from simple polymeric carriers to smart-complex protein-polymer assemblies, such as nanoreactors or synthetic organelles. Polymeric vesicles generated by the self-assembly of amphiphilic copolymers (polymersomes) offer the advantage of simultaneous encapsulation of hydrophilic compounds in their aqueous cavities and the insertion of fragile, hydrophobic compounds in their membranes. This strategy has permitted us and others to design and develop new systems such as nanoreactors and artificial organelles in which active compounds are simultaneously protected and allowed to act in situ. In recent years, we have created a variety of multifunctional, proteinpolymersomes combinations for biomedical applications. The insertion of membrane proteins or biopores into the polymer membrane supported the activity of co-encapsulated enzymes that act in tandem inside the cavity or of combinations of drugs and imaging agents. Surface functionalization of these nanocarriers permitted specific targeting of the desired biological compartments. Polymeric vesicles alone are relatively easy to prepare and functionalize. Those features, along with their stability and multifunctionality, promote their use in the development of new theranostic strategies. The combination of polymer vesicles and biological entities will serve as tools to improve the observation and treatment of pathological events and the overall condition of the patient.     

Surface-engineered magnetic nanoparticle platforms for cancer imaging and therapy

Enormous efforts have been made toward the translation of nanotechnology into medical practice, including cancer management. Generally the applications have fallen into two categories: diagnosis and therapy. Because the targets are often the same, the development of separate approaches can miss opportunities to improve efficiency and effectiveness. The unique physical properties of nanomaterials enable them to serve as the basis for superior imaging probes to locate and report cancerous lesions and as vehicles to deliver therapeutics preferentially to those lesions. These technologies for probes and vehicles have converged in the current efforts to develop nanotheranostics, nanoplatforms with both imaging and therapeutic functionalities. These new multimodal platforms are highly versatile and valuable components of the emerging trend toward personalized medicine, which emphasizes tailoring treatments to the biology of individual patients to optimize outcomes. The close coupling of imaging and treatment within a theranostic agent and the data about the evolving course of an illness that these agents provide can facilitate informed decisions about modifications to treatment. Magnetic nanoparticles, especially superparamagnetic iron oxide nanoparticles (IONPs), have long been studied as contrast agents for magnetic resonance imaging (MRI). Owing to recent progress in synthesis and surface modification, many new avenues have opened for this class of biomaterials. Such nanoparticles are not merely tiny magnetic crystals, but potential platforms with large surface-to-volume ratios. By taking advantage of the well-developed surface chemistry of these materials, researchers can load a wide range of functionalities, such as targeting, imaging and therapeutic features, onto their surfaces. This versatility makes magnetic nanoparticles excellent scaffolds for the construction of theranostic agents, and many efforts have been launched toward this goal. In this Account, we introduce the surface engineering techniques that we and others have developed, with an emphasis on how these techniques affect the role of nanoparticles as imaging or therapeutic agents. We and others have developed a set of chemical methods to prepare magnetic nanoparticles that possess accurate sizes, shapes, compositions, magnetizations, relaxivities, and surface charges. These features, in turn, can be harnessed to adjust the toxicity and stability of the nanoparticles and, further, to load functionalities, via various mechanisms, onto the nanoparticle surfaces.     

Surface modified cellulose nanocrystalline hybrids actualizing efficient and precise delivery of doxorubicin into nucleus with: In vitro and in vivo evaluation

Rod-like-shape nanomedicines with the ability of lysosomal pH-controlled drug release can precisely deliver doxorubicin (DOX) into its target, nucleus, and can fully exert its anticancer effect. Taking advantage of their large specific surface area, cellulose nanocrystals (CNCs) were used to fabricate pH-responsive DOX-loaded rod-like shaped hybrids nanomedicines: cis-aconityl-doxorubicin (CAD)@polyethylenimine (PEI)@CNCs (CAD@PEI@CNCs) via layer-by-layer (LbL) assembly. In vitro, CAD@PEI@CNCs hybrids displayed rod-like shape, high drug loading content, lysosomal pH-controlled drug release, efficient and precise doxorubicin (DOX) delivering into the nucleus. Moreover, the cellular uptake of CAD@PEI@CNCs hybrids was 20.9 folds higher than that of DOX·HCl against A549 cells. The cytotoxicity of CAD@PEI@CNCs hybrids was much higher than that of DOX·HCl and the pH-irresponsive hybrids against A549 cell. In vivo, CAD@PEI@CNCs hybrids exhibited good antitumor effect: (42.0 ± 6)% inhibition rate and few harms to the nude mice. Altogether, rod-like shaped pH-responsive CAD@PEI@CNCs hybrids nanomedicines could efficiently overcome the vascular and tumor barriers, and precisely deliver DOX to nucleus to convert DOX antitumor effects. These results indicate that CAD@PEI@CNCs have great potential to act as advanced nanomedicines with enhanced delivery efficiency and therapeutic efficiency.     

Interaction of amphiphilic polymers with model membranes

The lipid bilayers of cell membranes are usually connected to two types of biopolymers: the cytoskeleton and the glycocalix. These structures are not only responsible for the stabilization of the lipid bilayer, they also alter the surface properties of the cells. Among the various attempts to mimick membrane properties using polymeric systems(¹), one method is the fixation of amphiphilic polymers via hydrophobic anchor groups to lipid bilayers. In the experiments reported here the influence of amphiphilic polymers on the morphology of giant unilamellar liposomes has been investigated. Therefore a series of amphiphilic polyvinylpyrrolidone and dextran derivatives has been synthesized. The fixation of these polymers to the liposomal membranes could be shown with a fluorescence-labelled derivative by using epifluorescence microscopy. The polymer-membrane interaction caused by the insertion of the anchor groups leads to drastic morphological changes in this model membrane system. The exclusive interaction with the outer membrane of multilamellar liposomes could be demonstrated by freeze fracture electron microscopy. In addition, the anchoring of a natural capsular polysaccharide in liposomes has been proven by immunofluorescence. In these experiments, also a clustering (patching) of the antigen caused by the binding of the antibody could be observed.     

Aptamer-Aptamer Chimera for Targeted Delivery and ATP-Responsive Release of Doxorubicin into Cancer Cells

Aptamers offer a great opportunity to develop innovative drug delivery systems that can deliver cargos specifically into targeted cells. In this study, a chimera consisting of two aptamers was developed to deliver doxorubicin into cancer cells and release the drug in cytoplasm in response to adenosine-5′-triphosphate (ATP) binding. The chimera was composed of the AS1411 anti-nucleolin aptamer for cancer cell targeting and the ATP aptamer for loading and triggering the release of doxorubicin in cells. The chimera was first produced by hybridizing the ATP aptamer with its complementary DNA sequence, which is linked with the AS1411 aptamer via a poly-thymine linker. Doxorubicin was then loaded inside the hybridized DNA region of the chimera. Our results show that the AS1411–ATP aptamer chimera was able to release loaded doxorubicin in cells in response to ATP. In addition, selective uptake of the chimera into cancer cells was demonstrated using flow cytometry. Furthermore, confocal laser scanning microscopy showed the successful delivery of the doxorubicin loaded in chimeras to the nuclei of targeted cells. Moreover, the doxorubicin-loaded chimeras effectively inhibited the growth of cancer cell lines and reduced the cytotoxic effect on the normal cells. Overall, the results of this study show that the AS1411–ATP aptamer chimera could be used as an innovative approach for the selective delivery of doxorubicin to cancer cells, which may improve the therapeutic potency and decrease the off-target cytotoxicity of doxorubicin.