Photosensitizer-gold nanorod composite for targeted multimodal therapy.

In this work, a DNA inter-strand replacement strategy for therapeutic activity is successfully designed for multimodal therapy. In this multimodal therapy, chlorin e6 (Ce6) photosensitizer molecules are used for photodynamic therapy (PDT), while aptamer-AuNRs, are used for selective binding to target cancer cells and for photothermal therapy (PTT) with near infrared laser irradiation. Aptamer Sgc8, which specifically targets leukemia T cells, is conjugated to an AuNR by a thiol-Au covalent bond and then hybridized with a Ce6-labeled photosensitizer/reporter to form a DNA double helix. When target cancer cells are absent, Ce6 is quenched and shows no PDT effect. However, when target cancer cells are present, the aptamer changes structure to release Ce6 to produce singlet oxygen for PDT upon light irradiation. Importantly, by combining photosensitizer and photothermal agents, PTT/PDT dual therapy supplies a more effective therapeutic outcome than either therapeutic modality alone.

Aptamer-conjugated multifunctional nanoflowers as a platform for targeting, capture, and detection in laser desorption ionization mass spectrometry.

Although many different nanomaterials have been tested as substrates for laser desorption and ionization mass spectrometry (LDI-MS), this emerging field still requires more efficient multifuncional nanomaterials for targeting, enrichment, and detection. Here, we report the use of gold manganese oxide (Au@MnO) hybrid nanoflowers as an efficient matrix for LDI-MS. The nanoflowers were also functionalized with two different aptamers to target cancer cells and capture adenosine triphosphate (ATP). These nanoflowers were successfully used for metabolite extraction from cancer cell lysates. Thus, in one system, our multifunctional nanoflowers can (1) act as an ionization substrate for mass spectrometry, (2) target cancer cells, and (3) detect and analyze metabolites from cancer cells.

Enrichment and detection of rare proteins with aptamer-conjugated gold nanorods.

Rare protein enrichment and sensitive detection hold great potential in biomedical studies and clinical practice. This work describes the use of aptamer-conjugated gold nanorods for the efficient enrichment of rare proteins from buffer solutions and human plasma. Gold nanorod (AuNR) surfaces were modified with a long PEG chain and a 15-mer thrombin aptamer for protein enrichment and detection. Studies of the effect of surface modification on enrichment efficiency of thrombin showed that a change of only one EG(6) linker unit, i.e., from 2EG(6) to 3EG(6), could increase thrombin protein capture efficiency by up to 47%. Furthermore, a 1 ppm sample of thrombin in buffer could be enriched with around 90% efficiency using a low concentration (0.19 nM) of gold nanorod probe modified with 3EG(6) spacer, and with the same probe, effective capture was achieved down to 10 ppb (1 ng) thrombin in plasma samples. In addition to α-thrombin enrichment, prothrombin was also efficiently captured from plasma samples via gold nanorods conjugated with 15-mer thrombin aptamer. Our work demonstrates efficient enrichment of rare proteins using aptamer-modified nanomaterials, which can be used in biomarker discovery studies.

Assembly of aptamer switch probes and photosensitizer on gold nanorods for targeted photothermal and photodynamic cancer therapy.

An aptamer switch probe (ASP) linking chlorin e6 (Ce6), a photosensitizer molecule, to the surface of gold nanorods (AuNRs) was used to target cancer cells for photodynamic therapy (PDT) and photothermal therapy (PTT). In the presence of target cancer cells, the ASP changes conformation to drive Ce6 away from the gold surface, thereby producing singlet oxygen for PDT upon light irradiation. Since each AuNR is modified with many ASP-Ce6 molecules, the AuNR-ASP-Ce6 conjugate yields enhanced binding and therapeutic effect by the added ability to carry many photosensitizers. In addition, absorption of radiation by the gold nanorods enables further cell destruction by the photothermal effect. Consequently, this multimodal AuNR-ASP-Ce6 conjugate offers a remarkably improved and synergistic therapeutic effect compared to PTT or PDT alone, providing high specificity and therapeutic efficiency, which can be generalized to other types of cancer therapies.

Pattern recognition of cancer cells using aptamer-conjugated magnetic nanoparticles.

Biocompatible magnetic nanosensors based on reversible self-assembly of dispersed magnetic nanoparticles into stable nanoassemblies have been used as effective magnetic relaxation switches (MRSw) for the detection of molecular interactions. We report, for the first time, the design of MRSw based on aptamer-conjugated magnetic nanoparticles (ACMNPs). The ACMNPs capitalize on the ability of aptamers to specifically bind target cancer cells, as well as the large surface area of MNPs to accommodate multiple aptamer binding events. The ACMNPs can detect as few as 10 cancer cells in 250 µL of sample. The ACMNPs' specificity and sensitivity are also demonstrated by detection in cell mixtures and complex biological media, including fetal bovine serum, human plasma, and whole blood. Furthermore, by using an array of ACMNPs, various cell types can be differentiated through pattern recognition, thus creating a cellular molecular profile that will allow clinicians to accurately identify cancer cells at the molecular and single-cell level.

Smart multifunctional nanostructure for targeted cancer chemotherapy and magnetic resonance imaging.

Targeted chemotherapy and magnetic resonance imaging of cancer cells in vitro has been achieved using a smart multifunctional nanostructure (SMN) constructed from a porous hollow magnetite nanoparticle (PHMNP), a heterobifunctional PEG ligand, and an aptamer. The PHMNPs were prepared through a three-step reaction and loaded with the anticancer drug doxorubicin while being functionalized with PEG ligands. Targeting aptamers were then introduced by reaction with the PEG ligands. The pores of the PHMNPs are stable at physiological pH, but they are subject to acid etching. Specific binding and uptake of the SMN to the target cancer cells induced by aptamers was observed. In addition, multiple aptamers on the surface of one single SMN led to enhanced binding and uptake to target cancer cells due to the multivalent effect. Upon reaching the lysosomes of target cancer cells through receptor-mediated endocytosis, the relatively low lysosomal pH level resulted in corrosion of the PHMNP pores, facilitating the release of doxorubicin to kill the target cancer cells. In addition, the potential of using SMN for magnetic resonance imaging was also investigated.

Detection of lysozyme magnetic relaxation switches based on aptamer-functionalized superparamagnetic nanoparticles.

Magnetic relaxation switch (MRSw) detection is based on aggregate formation or dissociation when magnetic nanoparticles (MNPs) bind to target molecules. In the aggregated state, the dephasing rate of nearby proton spins is higher than in the dispersed state, resulting in a decrease in the spin-spin relaxation time, T(2). In this work, an MRSw-based nanosensor for lysozyme (Lys) protein detection was achieved using iron oxide nanoparticles conjugated with either Lys aptamer or linker DNA, which can hybridize with the extended part of the aptamer to form clusters. Upon the addition of Lys, the aptamers bind with their targets, leading to disassembly of clusters and an increase in T(2). A detection limit in the nanomolar range was achieved for Lys detection in both buffer and human serum. The determination of Lys level in different types of cancer cell lysates was also performed to demonstrate detection in real clinical samples.

Engineered multifunctional nanotools for biological applications.

Smart multifunctional magnetic nanoparticles are popular candidates for several biological applications owing to their intrinsic magnetic property and diverse applications that range from rare protein separation and biomedical utilization to cancer therapy and diagnostics. A universal protocol, for the development of such nanocarriers, is highly desirable for scientists with different backgrounds so that custom-made multifunctional nanoparticles can be developed to address their needs, among which are the superparamagnetic iron oxide and manganese oxide nanoparticles that are synthesized through high temperature decomposition reactions. However, an interface is needed to present these inorganic materials to biomolecules to enhance their application for different biological use. This compatibility is achieved by introducing a class of multifunctional copolymers. Magnetic nanoparticles are elaborately decorated with copolymers that carry three principle functionalities as follows: (1) dopamine moieties for surface anchorage of metal oxides; (2) dyes for optical detection; and (3) a large variety of functional molecules such as amines or carboxylates for conjugation of various biomolecules (i.e., proteins, nucleic acids, enzymes, etc.). These copolymers, in combination with nanoparticles, serve as a tool box that results in engineered nanotools with customized modifications and functionalities for applications in fields ranging from proteomics -bioseparation to tumor therapy.

Aptamer-conjugated nanomaterials for bioanalysis and biotechnology applications.

In recent years, nanomaterials have captured the attention of scientists from a wide spectrum of domains. With their unique properties, nanomaterials offer great promise for numerous applications, ranging from catalysis to energy harvesting and information technology. Functionalized with the desired biomolecules, nanomaterials can also be utilized for many biomedical applications. This paper summarizes recent achievements in the use of aptamer-conjugated nanomaterials for bioanalysis and biotechnology applications. First, we discuss the features and properties of aptamers and then illustrate the use of aptamer-conjugated nanomaterials as sensing platforms and delivery vehicles, emphasizing how such integration can result in enhanced sensitivity and selectivity.

The 2'-5'-oligoadenylate synthetase in the lowest metazoa: isolation, cloning, expression and functional activity in the sponge Lubomirskia baicalensis.

Aquatic animals, especially filter feeders such as sponges [phylum Porifera], are exposed to a higher viral load than terrestrial species. Until now, the antiviral defense system in the evolutionary oldest multicellular organisms, sponges, is not understood. One powerful protection of vertebrates against virus infection is mediated by the interferon (IFN)-inducible 2'-5'-oligoadenylate synthetase [(2-5)A synthetase] system. In the present study we cloned from the freshwater sponge Lubomirskia baicalensis a cDNA encoding a 314 aa long ORF with a calculated size of 35748Da, a putative (2-5)A synthetase, and raised antibodies against the recombinant protein. The native enzyme was identified in a crude extract from L. baicalensis by application of a novel separation procedure based on polymer coated ferromagnetic nanoparticles. The particles were derivatized with a synthetic double-stranded RNA [dsRNA], synthetic poly(I:C), a known allosteric activator of the latent (2-5)A synthetase. These particles were used to separate a single 35kDa protein from a crude extract of L. baicalensis, which cross-reacted with antibodies raised against the sponge enzyme. In situ hybridization studies revealed that highest expression of the gene is seen in cells surrounding the aquiferous canals. Finally primmorphs, an in vitro cell culture system, from L. baicalensis were exposed to poly(I:C); they responded to this dsRNA with an increased expression of the (2-5)A synthetase gene already after a 1-day incubation period. We conclude that sponges contain the (2-5)A synthetase antiviral protection system.

Superparamagnetic gamma-Fe(2)O(3) nanoparticles with tailored functionality for protein separation.

Polymer coated superparamagnetic gamma-Fe(2)O(3) nanoparticles were derivatized with a synthetic double-stranded RNA [poly(IC)], a known allosteric activator of the latent (2-5)A synthetase, to separate a single 35 kDa protein from a crude extract which cross reacted with antibodies raised against the sponge enzyme.