A Solvent-Mediated Excited-State Intermolecular Proton Transfer Fluorescent Probe for Fe3+ Sensing and Cell Imaging.

Constructing excited-state intermolecular proton transfer (ESIPT-e) fluorophores represents significant challenges due to the harsh requirement of bearing a proton donor-acceptor (D-A) system and their matching proton donating-accepting ability in the same molecule. Herein, we synthesized a new-type ESIPT-e fluorophor (2-APC) using the "four-component one-pot" reaction. By the installing of a cyano-group on pyridine scaffold, the proton donating ability of -NH2 was greatly enhanced, enabling 2-APC to undergo ESIPT-e process. Surprisingly, 2-APC exhibited dual-emissions in protic solvents ethanol and normal fluorescence in aprotic solvents, which is vastly different from that of conventional ESIPT-a dyes. The ESIPT emission can be obviously suppressed by Fe3+ due to the coordination reaction of Fe3+ with the A-D system in 2-APC. From this basis, a highly sensitive and selective method was established using 2-APC as a fluorescent probe, which offers the sensitive detection of Fe3+ ranging from 0 to 13 µM with the detection limit of 7.5 nM. The recovery study of spiked Fe3+ measured by the probe showed satisfactory results (97.2103.4%) with the reasonable RSD ranging from 3.1 to 3.8%. Moreover, 2-APC can also exhibit aggregation-induced effect in poor solvent or solid-state, eliciting strong red fluorescence. 2-APC was also applied to cell-imaging, exhibiting good cell-permeability, biocompatibility and color rendering. This multi-mode emission of 2-APC is significant departure from that of conventional extended p-conjugated systems and ESIPT dyes based on a flat and rigid molecular design. The "one-pot synthesis" strategy for the construction of ESIPT molecules pioneered a new route to achieve tricolor-emissive fluorophores.

Partnered Excited-State Intermolecular Proton Transfer Fluorescence (P-ESIPT) Signaling for Nitrate Sensing and High-Resolution Cell-Imaging.

Nitrite (NO2-) is a common pollutant and is widely present in the environment and in human bodies. The development of a rapid and accurate method for NO2- detection is always a very important task. Herein, we synthesized a partnered excited-state intermolecular proton transfer (ESIPT) fluorophore using the "multi-component one pot" method, and used this as a probe (ESIPT-F) for sensing NO2-. ESIPT-F exhibited bimodal emission in different solvents because of the solvent-mediated ESIPT reaction. The addition of NO2- caused an obvious change in colors and tautomeric fluorescence due to the graft of NO2- into the ESIPT-F molecules. From this basis, highly sensitive and selective analysis of NO2- was developed using tautomeric emission signaling, achieving sensitive detection of NO2- in the concentration range of 0~45 mM with a detection limit of 12.5 nM. More importantly, ESIPT-F showed the ability to anchor proteins and resulted in a recognition-driven "on-off" ESIPT process, enabling it to become a powerful tool for fluorescence imaging of proteins or protein-based subcellular organelles. MTT experimental results revealed that ESIPT-F is low cytotoxic and has good membrane permeability to cells. Thus, ESIPT-F was further employed to image the tunneling nanotube in vitro HEC-1A cells, displaying high-resolution performance.

A solvent-assisted ESIPT fluorescent dye for F-/Ag+ sensing and high-resolution imaging of the cilia in live cells.

A solvent-assisted ESIPT fluorescent dye was synthesized and used as a probe (2-PPN) for the detection of F-/Ag+ and high-resolution imaging of the cilia in live cells. The developed ESIPT fluorophore exhibited strong tautomeric fluorescence in protic solvents and normal emission in aprotic solvents, which is a significant departure from that of conventional intramolecular ESIPT compounds. The H-binding interaction of F- and the chelation of Ag+ with the ESIPT module of 2-PPN resulted in significant tautomeric emission quenching. From this basis, the 2-PPN-based assays for the detection of F- and Ag+ were established. The detection limit for F- and Ag+ sensing is 2.4 nM and 1.5 nM, respectively. The selective experimental results showed that no tautomeric fluorescence change of 2-PPN could be observed in the presence of the other inorganic ions in the same medium, revealing high selectivity of 2-PPN to F- and Ag+. Furthermore, MTT assay experiments proved that the probe 2-PPN exhibited low cytotoxicity and good cell membrane permeability. The probe was also further successfully utilized to image the cilia in vitro MCF7 cells, displaying its high-resolution imaging performance.Graphical abstract.

Electrochemical detection of PCR amplicons of Escherichia coli genome based on DNA nanostructural probes and polyHRP enzyme.

Fast, portable and sensitive analysis of E. coli is becoming an important challenge in many critical fields (e.g., food safety, environmental monitoring and clinical diagnosis). Thus, electrochemical biosensing of PCR amplicons from the bacterial genome has attracted reasonable research attention. In this work, we utilized a 3D DNA tetrahedral probe to establish a "sandwich-type" electrochemical DNA biosensor for sensitive and specific analysis of a 250 bp unpurified PCR amplicon from the uidA gene of the E. coli genome. Asymmetric PCR was used to produce single-stranded PCR products. Streptavidin-polyHRP80 was employed to improve the signal gain during electrochemical detection. We optimized important experimental conditions for DNA sensing, including the streptavidin-polyHRP, the signal probe and the ion strength. Finally, we achieved a remarkable sensitivity of 10 fM synthetic DNA target, and successfully performed the analysis of PCR amplicons from as low as 0.2 pg µL(-1) of E. coli genome. Compared with traditional single stranded DNA (ssDNA) probe based detection, our present work demonstrated 3 orders of magnitude improvement in sensitivity. In addition, our electrochemical DNA biosensor was 4 orders of magnitude more sensitive than normal electrophoretic analysis of PCR products. Our work made important progress in DNA nanostructured probe-based biosensors toward application in real applications.

Synthesis and receptor binding assay of indolin-2-one derivatives as dopamine D4 receptor ligands.

Five indolin-2-one derivatives bearing piperazinylbutyl side chains attached to the amide nitrogen were synthesized from 2-indolinone. 1-(4-Bromobutyl)-indolin-2-one was reacted with 1-piperazinecarboxaldehyde to form 1-(4-(4-formyl-1-piperazinyl)butyl)indolin-2-one (2). In the presence of H2SO4, the aldehyde moiety was removed from 1-(4-(4-formyl-1-piperazinyl)butyl)indolin-2-one and then 1-(4-(1-piperazinyl)butyl)indolin-2-one (3) was obtained, this compound was reacted with benzaldehyde derivatives to give the target compounds 4 a-e by N-alkylation reaction. The structures of the intermediates and the target compounds were characterized by 1H NMR, ESI-MS spectra and elemental analyses. In vitro receptor binding assays at D2, D3, D4 receptor subtypes of the target compounds were performed and the five compounds showed selectivity towards D2-like receptors. Among them, 1-(4-(4-(4-hydroxybenzy)-1-piperazinyl)butyl) indolin-2-one (4c) exhibited a remarkable affinity and selectivity to D4 receptor with K(i) value of 0.5 nM. The results indicated that 1-(4-(4-(4-hydroxybenzy)-1-piperazinyl)butyl)indolin-2-one might be a potential dopamine D4 receptor ligand.

Metal ion-mediated assembly of DNA nanostructures for cascade fluorescence resonance energy transfer-based fingerprint analysis.

Contamination of heavy metal ions in an aquatic environment poses a serious threat to human health. More seriously, heavy metal ions are usually present in the environment in a mixture, and the synergetic toxicity of multiple heavy metal ions is revealed (Aragay et al. Chem. Rev. 2011, 111, 3433; Chu et al. Aquat. Toxicol. 2002, 61, 53). Unfortunately, most of the existing methods based on DNA sequences are focusing on the detection of one type of metal ions. Simple and multiplexed detection of multiple metal ions has been poorly investigated and remains challenging. Here, we re-engineered the DNA sequences for Pb(2+), Hg(2+), and Ag(+), through which the binding of multiple metal ions initiated the self-assembly of these DNA sequences. On the basis of our rationally designed multicolor fluorescent labeling of the DNA sequences, cascade fluorescence resonance energy transfer (FRET) occurred. As a result, a fingerprint fluorescent spectrum was produced to indicate the presence of a single type of metal ions or multiple metal ions. The major advantages of our cascade FRET fingerprint technology include the following: (1) the "mix and read" detection mode in homogeneous solution is simple without the need of complicated instruments; (2) only single excitation is required to provide the cascade FRET fingerprint spectrum; (3) multiplexed detection capability can be realized intuitively and sensitively.

A polystyrene-based ESIPT fluorescent polymeric probe for highly sensitive detection of chromium(vi) ions and protein staining.

A "two-step" preparation method of an excited-state intermolecular proton transfer (ESIPT) fluorescent polymer (f-PP) is reported here. The synthesis of f-PP involves the acetylation of polystyrene and a "multicomponent one pot" reaction. The as-prepared polymer bears a group of ESIPT fluorescent units, enabling it to exhibit high brightness, moderate solubility and ESIPT fluorescence. F-PP gives off tautomeric bright green fluorescence under UV-tamp and the dual-emission could be specifically suppressed by Cr(vi). This phenomenon cannot be elicited by other competing species. On this basis, an ESIPT polymeric probe-based method for the determination of Cr(vi) was developed, offering high sensitivity (19.5 nM) and selectivity. The f-PP was successfully used to detect Cr(vi) in real water samples by standard adding methods, indicating its application feasibility.

A fluorescent probe based on modulation of ESIPT signaling for the highly selective detection of N2H4 and cell-imaging.

The broad occurrence of the hydrazine (N2H4) residues in aqueousenvironment is a potential threat to human health. Currently, the mainstream strategy for designing N2H4-specific probes is to functionalize a fluorophore with nucleophilic sites for the reductionreaction with N2H4. In this work, we designed and synthesized an excited-state intermolecular proton transfer (inter-ESPT) fluorescent dye(2-amino-4-(4-methoxyphenyl)-7,8-dihydro-5H-spiro[quinoline-6,2'-[1,3]dioxolane]-3-carbonitrilem, DQN) and used it as a probe to sense N2H4. DQN exhibits blue fluorescence in conventional solvents, which is assigned to its normal emission. In the presence of N2H4, the probe DQN can anchor the N2H4 molecule via hydrogen binding, enabling DQN to undergo inter-ESPT process and light up its tautomeric fluorescence. From this basis, an inter-ESPT-based method for N2H4 detection was established, offering high selectivity and sensitivity (11.5 nM). Furthermore, we demonstrated that the probe DQN can recognize the proteins in living cells, affording cell-imaging. This research provides a promising sensing strategy for monitoring N2H4 in water environments and this inter-ESPT dye is a powerful tool for cell-imaging.

Spectral Properties Echoing the Tautomerism of Milrinone and Its Application to Fe3+ Ion Sensing and Protein Staining.

Knowledge on the spectral properties of the tautomers of milrinone (MLR) in solvents and solid-state, as well as under light conditions is of critical importance from both theoretical and practical points of view. Herein, we investigated the spectral properties of MLR in different conditions using UV-Vis and fluorescence spectroscopies. The experimental results demonstrated that MLR can undergo the tautomerization reaction induced by solvent polarity, light and pH, eliciting four tautomeric structures (enol, keto, anion, and cation forms). The interesting multi-functional groups in MLR enable it to coordinate with metal ions or to recognize gust molecules by H-bonding. In the use of MLR as an excited-state intermolecular proton transfer (inter-ESPT) fluorescent probe, a highly sensitive and selective analysis of Fe3+ was developed, which offered a sensitive detection of Fe3+ with the detection limit of 3.5 nM. More importantly, MLR exhibited the ability of anchoring proteins and led to the recognition-driven turn-on inter-ESPT process, highlighting the potential for the probe to image proteins in electrophoresis gels. The spectral experimental results revealed the possible degradation mechanism, so that we can better understand the side effects of oral preparations. The use of the available drug as an inter-ESPT fluorescent probe is simple and accurate, providing a good method for Fe3+ ion sensing and protein staining.

Detection of Single Nucleotide Polymorphisms by Fluorescence Embedded Dye SYBR Green I Based on Graphene Oxide.

The detection of single nucleotide polymorphisms (SNPs) is of great significance in the early diagnosis of diseases and the rational use of drugs. Thus, a novel biosensor based on the quenching effect of fluorescence-embedded SYBR Green I (SG) dye and graphene oxide (GO) was introduced in this study. The probe DNA forms a double helix structure with perfectly complementary DNA (pcDNA) and 15 single-base mismatch DNA (smDNA) respectively. SG is highly intercalated with perfectly complementary dsDNA (pc-dsDNA) and exhibits strong fluorescence emission. Single-base mismatch dsDNA (SNPs) has a loose double-stranded structure and exhibits poor SG intercalation and low fluorescence sensing. At this time, the sensor still showed poor SNP discrimination. GO has a strong effect on single-stranded DNA (ssDNA), which can reduce the fluorescence response of probe DNA and eliminate background interference. And competitively combined with ssDNA in SNPs, quenching the fluorescence of SG/SNP, while the fluorescence value of pc-dsDNA was retained, increasing the signal-to-noise ratio. At this time, the sensor has obtained excellent SNP resolution. Different SNPs detect different intensities of fluorescence in the near-infrared region to evaluate the sensor's identification of SNPs. The experimental parameters such as incubation time, incubation temperature and salt concentration were optimized. Under optimal conditions, 1 nM DNA with 0-10 nM linear range and differentiate 5% SNP were achieved. The detection method does not require labeling, is low cost, simple in operation, exhibits high SNP discrimination and can be distinguished by SNP at room temperature.

Intrinsically ESIPT-exhibiting and enhanced emission in polymer nanoparticles as signaling for sensing nitrite.

A straightforward approach to the fabrication of intrinsically excited-state intramolecular proton transfer (ESIPT)-fluorescent polymer nanoparticles (e-PNPs) was developed. The e-PNPs were obtained by self-assembly of the homopolymers derived from 4-aminosalicylic acid in aqueous solution. By incorporating ESIPT modules into polymer nanoparticles, the ESIPT reaction can be endowed with moderate hydrophobic micro-environment by nanoparticle scaffolds, eliciting enhanced ESIPT emission. The newly developed e-PNPs exhibit strong tautomeric fluorescence(e-FL), good photostability, low-toxicity and favourable biocompatibility in aqueous solution. Upon the addition of NO2-, the e-FL can be significantly quenched owing to the reaction of NO2- with the amide groups on e-PNPs. From this basis, the fluorescence detection of NO2- was implemented, which showed a linear relationship between 0 nM and 110 nM with a detection limit of 2.3 nM. Furthermore, e-PNPs were used as nanoprobes to monitor the NO2- levels in HeLa cells by fluorescence imaging, demonstrating the ability of discrimination from different concentrations of NO2-. The proposed method can be applied to a wide range of other ESIPT modules to integrate into polymer nanoparticles and offer highly sensitive nanosensing platform for bioanalysis and molecular imaging.

A specific nanoprobe for cysteine based on nitrogen-rich fluorescent quantum dots combined with Cu2.

As a new member of the carbon quantum-dot family, fluorescent nitrogen-rich quantum dots (NRQDs) were prepared by a mixed solvothermal method using 2-azidoimidazole and aqueous ammonia as reactants. These NRQDs are rich in nitrogen up to 40.2%, which are endowed with high fluorescence quantum yield, good photostability, water-solubility and favourable biocompatibility. We further explored the use of NRQDs combined with Cu2+ as a nanoprobe for sensing fluorescently of cysteine (Cys) in complex biological samples. In this sensing system, the fluorescence is significantly quenched via energy transfer from NRQDs to Cu2+ for the coordination of amino-containing groups with Cu2+. The strong affinity between Cu 2+ and Cys leads to the formation of Cu2+-Cys complexes and cause the detachment of Cu2+ from the surface of NRQDs, thus the fluorescence of NRQDs recover. This nanoprobe allows analysis of Cys by modulating the switch of the fluorescence of NRQDs with a detection limit of 5.3nM. As expected, the proposed NRQDs-Cu2+complex-based nanoprobes were successfully applied for the determination of Cys in human serum and plasma samples with recoveries ranging from 97.2% to 105.7%. The probe ensemble was also successfully applied to imaging of Cys in living cells with satisfactory results, which shows strong potential for clinical diagnosis.

Intrinsically fluorescent and highly functionalized polymer nanoparticles as probes for the detection of zinc and pyrophosphate ions in rabbit serum samples.

Intrinsically fluorescent polymer nanoparticles (F-PNPs) were synthetized from 2-hydroxy-5-methylisophthalaldehyde and melamine by solvothermal method. F-PNPs can emit strong yellow green fluorescence at 542 nm without the conjugation to any external fluorescent agent and surface modification. Owing to the abundant amino and hydroxyl groups on their surface, the F-PNPs possess multiple binding sites, good biocompatibility and excellent water-solubility. Addition of Zn2+ to the F-PNPs solution resulted in a blue shift (Δλ=40 nm) with obvious enhancement in the fluorescence intensity at 502 nm; while there was negligible change in the presence of other metal ions. The subsequent treatment with pyrophosphate (PPi) can cause fluorescence recovery of F-PNPs by pulling the Zn2+ out of the coordination cavity of F-PNPs-Zn2+ nanocomposites. No interference was observed from other anions and nucleotides, making the F-PNPs-Zn2+ ensembles highly sensitive and selective nanoprobes for PPi. The detection limit is 2.75 × 10-8 M/L and 7.63 × 10-8 M/L for Zn2+ and PPi, respectively. The proposed nanoprobes were then used for detecting the recovery of Zn2+ and PPi in rabbit serum samples, which were found to be 99.4-104.2% and 98.6-104.7%, respectively. The present strategy for the fabrication of nanoparticles may offer a new sight for the preparation of polymer nanostructures. The F-FNPs based probes can provide an accurate method for the detection of Zn2+ and PPi in serum samples.

Targeted Imaging of Brain Tumors with a Framework Nucleic Acid Probe.

Development of agents for delivering drugs and imaging probes across the blood-brain barrier (BBB) remains a major challenge. In this study, we designed a biocompatible framework nucleic acid (FNA)-based imaging probe for brain tumor-targeting. We employed a typical type of FNAs, tetrahedral DNA nanostructures (TDNs), as the building block, which were modified with angiopep-2 (ANG), a 19-mer peptide derived from human Kunitz domain of aprotinin. This probe exhibited high binding efficiency with low-density lipoprotein receptor-related protein-1 (LRP-1) of BBB and glioma. We found that ANG-functionalized TDNs (ANG-TDNs) stayed intact for at least 12 h in serum, and that ANG modification effectively enhanced cellular uptake of TDNs in brain capillary endothelial cells and Uppsala 87 malignant glioma (U87MG) cells. Remarkably, studies in both in vitro and in vivo models revealed that ANG-TDNs could cross the BBB. Especially, in vivo imaging showed strong fluorescent signals in U87MG human glioblastoma xenograft in nude mice. This study establishes that the FNA-based platform provides a new theranostic tool for the study and therapy of brain tumors.

Multiple-Armed Tetrahedral DNA Nanostructures for Tumor-Targeting, Dual-Modality in Vivo Imaging.

In this work, we have developed multiple-armed DNA tetrahedral nanostructures (TDNs) for dual-modality in vivo imaging using near-infrared (NIR) fluorescence and single-photon emission computed tomography (SPECT). We found that the presence of arm strands in TDNs remarkably enhanced their in vitro stability, allowing them to stay intact for at least 12 h in serum. By using NIR fluorescence imaging, we evaluated in mice the pharmacokinetics of TDNs, which exhibited distinctly different in vivo biodistribution patterns compared with those of double-stranded (ds)DNA. We also noticed that TDNs had twofold longer circulation time in the blood system than that of dsDNA. With the use of multiple-armed TDNs, we could precisely anchor an exact number of functional groups including tumor-targeting folic acid (FA), NIR emitter Dylight 755, and radioactive isotope (99m)Tc on prescribed positions of TDNs, which showed the capability of targeted imaging ability in cancer cells. Furthermore, we realized noninvasive tumor-targeting imaging in tumor-bearing mice by using both NIR and SPECT modalities.

Radiolabelling of poly(histidine) derivatized biodegradable microspheres with the 188Re tricarbonyl complex [188Re(CO)3(H2O)3]+.

OBJECTIVES: Many radiopharmaceuticals have been studied as radiation synovectomy agents. In this study, we developed a new potential agent for radiation synovectomy: poly(lactic acid)-histidine (PLA-his) microspheres radiolabelled with [188Re(CO)3(H2O)3]+. METHODS: The reaction conditions for the chelation of [188Re(CO)3(H2O)3]+ and the radiolabelling of PLA microspheres were optimized and the stabilities for both steps tested in vitro. RESULTS: The chelation efficiency of [188Re(CO)3(H2O)3]+ reached 93.12 +/- 1.82% with >95% radiochemical purity once the colloidal and free 188Re were removed by a small Sep-Pak column (Plus QMA). More than 90% of radioactivity stayed in the [188Re(CO)3(H2O)3]+ form over 5 h. The radiolabelling efficiency of PLA-his microspheres with [188Re(CO)3(H2O)3]+ was above 92%. After 3 days incubation at 37 degrees C in calf serum, more than 80% of the radioactivity was still bound to the microspheres. CONCLUSION: Such microspheres are potentially useful as a radiation synovectomy agent for the treatment of chronically inflamed arthritic joints. Furthermore, they might be valuable in cancer brachytherapy.

Constructing Higher-Order DNA Nanoarchitectures with Highly Purified DNA Nanocages.

DNA nanostructures have attracted great attention due to their precisely controllable geometry and great potential in various areas including bottom-up self-assembly. However, construction of higher-order DNA nanoarchitectures with individual DNA nanostructures is often hampered with the purity and quantity of these "bricks". Here, we introduced size exclusion chromatography (SEC) to prepare highly purified tetrahedral DNA nanocages in large scale and demonstrated that precise quantification of DNA nanocages was the key to the formation of higher-order DNA nanoarchitectures. We successfully purified a series of DNA nanocages with different sizes, including seven DNA tetrahedra with different edge lengths (7, 10, 13, 17, 20, 26, 30 bp) and one trigonal bipyramid with a 20-bp edge. These highly purified and aggregation-free DNA nanocages could be self-assembled into higher-order DNA nanoarchitectures with extraordinarily high yields (98% for dimer and 95% for trimer). As a comparison, unpurified DNA nanocages resulted in low yield of 14% for dimer and 12% for trimer, respectively. AFM images cleraly presented the characteristic structure of monomer, dimer and trimer, impling the purified DNA nanocages well-formed the designed nanoarchitectures. Therefore, we have demonstrated that highly purified DNA nanocages are excellent "bricks" for DNA nanotechnology and show great potential in various applications of DNA nanomaterials.

Universal Fluorescence Biosensor Platform Based on Graphene Quantum Dots and Pyrene-Functionalized Molecular Beacons for Detection of MicroRNAs.

A novel biosensor platform was developed for detection of microRNAs (miRNAs) based on graphene quantum dots (GQDs) and pyrene-functionalized molecular beacon probes (py-MBs). Pyrene was introduced to trigger specifically fluorescence resonance energy transfer (FRET) between GQDs and fluorescent dyes labeled on py-MBs, and the unique fluorescent intensity change produced a novel signal for detection of the target. The platform realized detection of miRNAs in a wide range from 0.1 nM to 200 nM with great discrimination abilities, as well as multidetection of different kinds of miRNAs, which paved a brand new way for miRNA detection based on GQDs.

A novel fluorescence sensor based on covalent immobilization of 3-amino-9-ethylcarbazole by using silver nanoparticles as bridges and carriers.

A novel technique of covalent immobilization of indicator dyes in the preparation of fluorescence sensors is developed. Silver nanoparticles are used as bridges and carriers for anchoring indicator dyes. 3-amino-9-ethylcarbazole (AEC) was employed as an example of indicator dyes with terminal amino groups and covalently immobilized onto the outmost surface of a quartz glass slide. First, the glass slide was functionalized by (3-mercaptopropyl) trimethoxysilane (MPS) to form a thiol-terminated self-assembled monolayer, where silver nanoparticles were strongly bound to the surface through covalent bonding. Then, 16-mercaptohexadecanoic acid (MHDA) was self-assembled to bring carboxylic groups onto the surface of silver nanoparticles. A further activation by using 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) converted the carboxylic groups into succinimide esters. Finally, the active succinimide esters on the surface of silver nanoparticles were reacted with AEC. Thus, AEC was covalently bound to the glass slide and an AEC-immobilized sensor was obtained. The sensor exhibited very satisfactory reproducibility and reversibility, rapid response and no dye-leaching. Rutin can quench the fluorescence intensity of the sensor and be measured by using the sensor. The linear response of the sensor to rutin covers the range from 2.0 x 10(-6) to 1.5 x 10(-4) molL(-1) with a detection limit of 8.0 x 10(-7) molL(-1). The proposed technique may be feasible to the covalent immobilization of other dyes with primary amino groups.

Surface modified superparamagnetic iron oxide nanoparticles: as a new carrier for bio-magnetically targeted therapy.

Amino-functionalized superparamagnetic iron oxide nanoparticles (SPION) were synthesized by coprecipitation method. The particles were characterized by X-ray diffraction (XRD), vibrating sample magnetometer (VSM), scanning electron micrographs (SEM), transmission electron micrographs (TEM) and atomic force micrographs (AFM). The size of the modified particles varied in the range 10-15 nm and did not change significantly after modification. Hepama-1, an excellent humanized monoclonal antibody directed against liver cancer, was conjugated to the SPION to prepare immuno-magnetic nanoparticles (IMN). A direct labeling method was employed to radiolabel IMN with rhenium-188. The radiolabeling efficiency was about 90% with good in vitro stability. (188)Re labeled IMN could markedly kill SMMC-7721 liver cancer cells. Such SPION might be very useful for bio-magnetically targeted radiotherapy in liver cancer treatment.