Jem-Mau Lo

Poly(N-isopropylacrylamide) hydrogels with interpenetrating multiwalled carbon nanotubes for cell sheet engineering.

Hydrogels have been developed as artificial extracellular matrixes (ECMs) to mimic native tissue microenvironments for various applications. Unfortunately, poly(N-isopropylacrylamide) (PNIPAAM)-based hydrogels are not suitable for cell culturing and cell sheet preparation. Carbon nanotubes (CNTs), with their mechanical strength and electrical conductivity, have been considered as additives to increase the applicability of hydrogels to cell encapsulation and advance cardiac electrophysiological functions. A simple method for fabrication of PNIPAAM hydrogels interpenetrated with multiwalled CNTs (MWCNTs) as substrates for cell sheet preparation is reported. The results demonstrate that PNIPAAM hydrogels with interpenetrating MWCNTs still exhibit thermosensitive behavior. It is also found that epithelial Madin-Darby canine kidney (MDCK) cells can only attach and proliferate on MWCNT-interpenetrated PNIPAAM hydrogels. Furthermore, the PNIPAAM hydrogels with MWCNTs possess higher elastic moduli and hydrophobicities than those without MWCNTs, suggesting these two characteristics are necessary for the cells to attach to the hydrogel surfaces. Moreover, cell sheets can only be harvested from PNIPAAM hydrogels with MWCNTs because of their high ratio of cell attachment. Thus, this simple method provides sufficient mechanical strength to PNIPAAM hydrogels so that anchorage-dependent cells can be cultivated and provides a superior system for preparing cell sheets.

Novel geometry type of nanocarriers mitigated the phagocytosis for drug delivery.

Target geometry for mitigating phagocytosis has garnered considerable attention recently in the drug delivery field. This study examined nanoparticles (NPs) with same volume but different shapes, namely, spherical NPs (SNPs) and hexagonal nanoprisms (HNPs), and analyzed their behaviors in vitro and in vivo. These NPs were constructed with a multifunctional block copolymer component, mPEG-b-P(HEMA-co-histidine-PLA). Geometry of SNPs and HNPs was controlled by adjusting copolymer properties and particle size was controlled by adjusting formulation parameters. Nanoparticle morphology had no effect in mitigating phagocytosis when NP size was 70 nm; however, morphology had a significant effect when NP size was 120 nm. The radioactivity-time curves for (99m)Tc-labeled NPs, fitted by the two-compartment pharmacokinetic model, show that the prolonged plasma distribution half-life of HNPs is indicative in the bloodstream. The in vitro and in vivo studies reveal that dual stealth characteristics, pegylation and hexagonal prism structure, of nanocarriers can be adopted in clinical application for safe and efficient delivery of cancer therapy.

In Vitro and in Vivo Evaluation of Lactoferrin-Conjugated Liposomes as a Novel Carrier to Improve the Brain Delivery

In this study, lactoferrin-conjugated PEGylated liposomes (PL), a potential drug carrier for brain delivery, was loaded with radioisotope complex, 99mTc labeled N,N-bis(2-mercaptoethyl)-N′,N′-diethylethylenediamine (99mTc-BMEDA) for in vitro and in vivo evaluations. The hydrophilicity of liposomes was enhanced by PEGylation which was not an ideal brain delivery system for crossing the blood brain barrier (BBB). With the modification of a brain-targeting ligand, lactoferrin (Lf), the PEGylated liposome (PL) might become a potential brain delivery vehicle. In order to test the hypothesis in vitro and in vivo, 99mTc-BMEDA was loaded into the liposomes as a reporter with or without Lf-conjugation. The mouse brain endothelia cell line, bEnd.3 cells, was cultured to investigate the potential uptake of liposomes in vitro. The in vivo uptake by the mouse brain of the liposomes was detected by tissue biodistribution study. The results indicated that Lf-conjugated PEGylated liposome showed more than three times better uptake efficiency in vitro and two-fold higher of brain uptake in vivo than PEGlyated liposome. With the success of loading the potential Single Photon Emission Tomography (SPECT) imaging probe, 99mTc-BMEDA, Lf-PL might serve as a promising brain delivery system for loading diagnostics or therapeutics of various brain disorders.

Syntheses and molecular structures of three Cu(II) complexes with tetradentate imine-phenols

Three Cu(II) complexes of N,N ′-bis-(salicylidene)-1,3-diiminopropane ( 1 ), N,N ′-bis-(salicylidene)-1,3-diimino-2,2-dimethylpropane ( 2 ), and N,N ′-bis-(salicylidene)-1,5-diiminopentane ( 3 ) have been prepared and characterized by X-ray diffraction. All of the three complexes are four coordinated with Cu(II) in a tetrahedrally distorted square-planar geometry to two imine N atoms and two phenolate O atoms. Both 1 and 2 are monomeric with a 6-6-6 chelate ring structure and display the 2N2O donor atoms in a normal, tetradentate “ cis ” configuration. However, in 3 two Cu(II) ions coordinate with bis-bidentate Schiff-base ligands, such that the Cu atoms are bridged by the two ligands; about each Cu atom, the arrangement of the iminophenolate groups is trans . The CuN1O1 and CuN2O2 planes intersect to form dihedral angles of 24.7° and 34.8° for 1 and 2 , respectively, while the dihedral angle of two bidentate chelate planes of 3 is 40.5°.

In vivo examination of 188Re (I)-tricarbonyl-labeled trastuzumab to target HER2-overexpressing breast cancer

INTRODUCTION Trastuzumab (Herceptin), a humanized IgG1 monoclonal antibody directed against the extracellular domain of the HER2 protein, acts as an immunotherapeutic agent for HER2-overexpressing human breast cancers. Radiolabeled trastuzumab with beta- or alpha emitters can be used as radioimmunotherapeutic agent for the similar purpose but with additional radiation effect. METHODS In this study, trastuzumab was labeled with (188)Re for radioimmunotherapy of HER2/neu-positive breast cancer. (188)Re(I)-tricarbonyl ion, [(188)Re(OH(2))(3)(CO)(3)](+), was employed as a precursor for directly labeling the monoclonal antibody with (188)Re. The immunoreactivity of (188)Re(I)-trastuzumab was estimated by competition receptor-binding assay using HER2/neu-overexpressive BT-474 human breast cancer cells. The localization properties of (188)Re(I)-trastuzumab within both tumor and normal tissues of athymic mice bearing BT-474 human breast cancer xenografts (HER2/neu-overexpressive) and similar mice bearing MCF-7 human breast cancer xenografts (HER2/neu-low expressive) were investigated. RESULTS When incubated with human serum albumin and histidine at 25 degrees C, (188)Re(I)-trastuzumab was found to be stable within 24 h. The IC(50) of (188)Re(I)-trastuzumab was found to be 22.63+/-4.57 nM. (188)Re(I)-trastuzumab was shown to accumulate specifically in BT-474 tumor tissue in in vivo biodistribution studies. By microSPECT/CT, the image of (188)Re localized BT-474 tumor was clearly visualized within 24 h. In contrast, (188)Re(I)-trastuzumab uptake in HER2-low-expressing MCF-7 tumor was minimal, and the (188)Re image at the localization of the tumor was dim. CONCLUSION These results reveal that (188)Re(I)-trastuzumab could be an appropriate radioimmunotherapeutic agent for the treatment of HER2/neu-overexpressing cancers.

Imaging, Autoradiography, and Biodistribution of 188Re-Labeled PEGylated Nanoliposome in Orthotopic Glioma Bearing Rat Model

The (188)Re-labeled pegylated nanoliposome (abbreviated as (188)Re-Liposome) was prepared and evaluated for its potential as a theragnostic agent for glioma. (188)Re-BMEDA complex was loaded into the pegylated liposome core with pH 5.5 ammonium sulfate gradient to produce (188)Re-Liposome. Orthotopic Fischer344/F98 glioma tumor-bearing rats were prepared and intravenously injected with (188)Re-Liposome. Biodistribution, pharmacokinetic study, autoradiography (ARG), histopathology, and nano-SPECT/CT imaging were conducted for the animal model. The result showed that (188)Re-Liposome accumulated in the brain tumor of the animal model from 0.28%±0.09% injected dose (ID)/g (n=3) at 1 hour to a maximum of 1.95%±0.35% ID/g (n=3) at 24 hours postinjection. The tumor-to-normal brain uptake ratio (T/N ratio) increased from 3.5 at 1 hour to 32.5 at 24 hours. Both ARG and histopathological images clearly showed corresponding tumor regions with high T/N ratios. Nano-SPECT/CT detected a very clear tumor image from 4 hours till 48 hours. This study reveals the potential of (188)Re-Liposome as a theragnostic agent for brain glioma.

Synthesis and structural characterization of a Re(V) complex with a 2N1S donor and the radiochemical behavior of its Tc analog.

A rhenium(V) complex with 2-(2-pyridylmethylthio)-aniline has been synthesized and characterized by UV-VIS absorption, IR, MS and X-ray crystallography. The complex contains a ReO3+ moiety and the amine compound, acting as a monobasic tridentate(NSN) ligand. The chemical behavior of its technetium analog has been studied radioanalytically by solvent extraction, TLC, electrophoresis and HPLC using 99mTc tracer.

The effect of PEG-5K grafting level and particle size on tumor accumulation and cellular uptake

PEG-modified gold nanoparticles (PEG-modified GNs) with diameters of 40 nm and 70 nm were prepared to elucidate the effect of extent of PEG (M.W. 5000) grafting and particle size on tumor accumulation and cellular uptake. Flow cytometry reveals that cellular uptake is strongly related to the size of PEG-modified GNs, rather than the extent of PEG-5K grafting level. Cytotoxicity analysis based on the intracellular release of drugs showed that the 70 nm PEG-modified GNs have the higher cytotoxicity, beccause of their greater cellular uptake. Also, particle size, rather than PEG-5K grafting level affects tumor accumulation. However, PEG-5K grafting level significantly affects the accumulation of particles in the liver and spleen. This finding is important in determining the proper PEG-5K grafting level and particle size for designing nano-medicines.

Chemical characteristics of 99mTc-labeled amine oximes

Abstract A series of alkylene amine oximes including En(AO) 2 , Pn(AO) 2 , DmPn(AO) 2 , HMPAO, Bn(AO) 2 and Pent(AO) 2 were synthesized and complexations of the amine oximes with a trace-level of 99m TcO 4 − were undertaken in the presence of Sn 2+ . The 99m Tc-amine oxime complexes obtained were characterized simultaneously by solvent extraction, TLC, electrophoresis and HPLC. The labeling yield, neutrality, lipophilicity and stability of the 99m Tc-amine oxime complexes were sufficiently investigated. According to the structures found by x-ray diffraction in previous literature, the complexes of 99 Tc with the ligands with 2-C and 3-C backbones [including En(AO) 2 , Pn(AO) 2 , DmPn(AO) 2 and HMPAO in the present work] are in the form of TcOL, where L is the ligand involved, whereas those with 4-C and 5-C backbones [including Bn(AO) 2 and Pent(AO) 2 ] are in the form of TcO 2 L. The chemical behaviors of the complex of no-carrier-added 99m Tc with the ligands found in observed study correlate with the TcOL-type and the TcO 2 L-type structures aforementioned.

Copper(II) complexes with tetradentate imine-phenols: synthesis, characterization and molecular structures

Four copper(II) complexes of N,N′-bis(4-methoxysalicylidene)-1,2-diimino ethanemonohydrate (1), N,N′-bis(5-methoxysalicylidene)-1,2-diiminoethane (2), N,N′-bis(3-methoxysalicylidene)-2,2-dimethyl-1,3-diiminopropane (3) and N,N′-bis(4-methoxysalicylidene)-2,2-dimethyl-1,3-diiminopropane (4) have been prepared and characterized spectroscopically. The solid-state structures of the complexes were established by X-ray crystallography. Complexes 2, 3 and 4 contain Cu(II) in a tetrahedrally distorted square planar environment with two phenolate O atoms being deprotonated. Complex 1 is five-coordinate and displays color isomerism.