Tandem time-of-flight mass spectrometer for photodissociation of biopolymer ions generated by matrix-assisted laser desorption ionization (MALDI-TOF-PD-TOF) using a linear-plus-quadratic potential reflectron

A tandem time-of-flight mass spectrometer for the study of photodissociation of biopolymer ions generated by matrix-assisted laser desorption ionization was designed and constructed. A reflectron with linear and quadratic (LPQ) potential components was used. Characteristics of the LPQ reflectron and its utility as the second stage analyzer of the tandem mass spectrometer were investigated. Performance of the instrument was tested by observing photodissociation of [M + H](+) from angiotensin II, a prototype polypeptide. Quality of the photodissociation tandem mass spectrum was almost comparable to that of the post-source decay spectrum. Monoisotopic selection of the parent ion was possible, which was achieved through the ion beam-laser beam synchronization. General theoretical considerations needed for a successful photodissociation of large biopolymer ions are also presented.     

Preparative and stereoselective synthesis of the versatile intermediate for carbocyclic nucleosides: effects of the bulky protecting groups to enforce facial selectivity

The preparative and stereoselective synthesis (45-50% overall yields) of the target compound 17 has been accomplished from D-ribose. The bulky protecting groups such as TBDPS and Trityl enforced the facial selectivity during Grignard reaction to give the tertiary beta-allylic alcohol 16 as the sole product, which was oxidatively rearranged to the key molecule 17 in excellent yield.     

Indium(III)chloride catalyzed synthesis of novel 1H-pyrazolo[1,2-b]phthalazine-5,10-diones and 1H-pyrazolo[1,2-a]pyridazine-5,8-diones under solvent-free condition

An efficient, inexpensive and environmentally friendly synthesis of novel 3-amino-2-benzoyl-1-aryl-1H-pyrazolo[1,2-b]phthalazine-5,10-dione and 3-amino-2-benzoyl-1-aryl-1H-pyrazolo[1,2-a]pyridazine-5,8-dione derivatives has been developed via one-pot three-component reaction of phthalhydrazide or maleic hydrazide, aldehydes and arylacetonitrile in the presence of catalytic amount of InCl₃ as a Lewis acid catalyst under solvent-free conditions. The most important features of the present protocol are mild reaction conditions, short reaction times, high yields, and a wide range of functional group tolerance.     

SSA-MOA: a novel CTC isolation platform using selective size amplification (SSA) and a multi-obstacle architecture (MOA) filter

Circulating tumor cells (CTCs) have gained increasing attention as physicians and scientists learn more about the role these extraordinarily rare cells play in metastatic cancer. In developing CTC technology, the critical criteria are high recovery rates and high purity. Current isolation methods suffer from an inherent trade-off between these two goals. Moreover, ensuring minimal cell stress and robust reproducibility is also important for the clinical application of CTCs. In this paper, we introduce a novel CTC isolation technology using selective size amplification (SSA) for target cells and a multi-obstacle architecture (MOA) filter to overcome this trade-off, improving both recovery rate and purity. We also demonstrate SSA-MOA's advantages in minimizing cell deformation during filter transit, resulting in more stable and robust CTC isolation. In this technique, polymer microbeads conjugated with anti-epithelial cell adhesion molecules (anti-EpCAM) were used to selectively size-amplify MCF-7 breast cancer cells, definitively differentiating from the white blood cells (WBCs) by avoiding the size overlap that compromises other size selection methods. 3 μm was determined to be the optimal microbead diameter, not only for size discrimination but also in maximizing CTC surface coverage. A multi-obstacle architecture filter was fabricated using silicon-on-glass (SOG) technology-a first such application of this fabrication technique-to create a precise microfilter structure with a high aspect ratio. The filter was designed to minimize cell deformation as simulation results predicted that cells captured via this MOA filter would experience 22% less moving force than with a single-obstacle architecture. This was verified by experiments, as we observed reliable cell capture and reduced cell deformation, with a 92% average recovery rate and 351 peripheral blood leukocytes (PBL) per millilitre (average). We expect the SSA-MOA platform to optimize CTC recovery rates, purity, and stability, increasing the sensitivity and reliability of such tests, thereby potentially expanding the utilization of CTC technologies in the clinic.     

Indocyanine green encapsulated nanogels for hyaluronidase activatable and selective near infrared imaging of tumors and lymph nodes

Indocyanine green (ICG) encapsulated hyaluronic acid (HA) nanogels were first studied for highly selective detection of specific cancers and lymph nodes via hyaluronidase sensitive switch-on of near infrared fluorescence as a long-lasting and stimuli-responsive imaging probe.     

Profiling surface glycans on live cells and tissues using quantum dot-lectin nanoconjugates

The surface of mammalian cells is densely coated with complex glycans, which are directly involved in cell-cell or cell-protein interactions that trigger various biological responses. Here, we present a novel glycomics approach that uses quantum dot (Qdot)-lectin nanoconjugates to interrogate the surface glycans of tissues and patterned cells. Our approach allows highly sensitive in situ monitoring of specific lectin-glycan interactions and quantitative information on surface glycans for each examined cell line and tissue. The results clearly show significant changes in glycosylation for each cell line and tissue sample. We expect that these results will be applicable in cancer diagnostics and promote the development of new analytical tools for glycomics.     

Carbonic Anhydrase Immobilized on Encapsulated Magnetic Nanoparticles for CO(2) Sequestration

Bovine carbonic anhydrase (BCA) was covalently immobilized onto OAPS (octa(aminophenyl)silsesquioxane)-functionalized Fe(3) O(4) /SiO(2) nanoparticles by using glutaraldehyde as a spacer. The Fe(3) O(4) nanoparticles were coated with SiO(2) , onto which was grafted OAPS, and the product was characterized using SEM, TEM, XRD, IR, X-ray photoelectron spectroscopy (XPS), and magnetometer analysis. The enzymatic activities of the free and Fe(3) O(4) /SiO(2) /OAPS-conjugated BCA (Fe?CA) were investigated by hydrolyzing p-nitrophenylacetate (p-NPA), and hydration and sequestration of CO(2) to CaCO(3) . The CO(2) conversion efficiency and reusability of the Fe?CA were studied before and after washing the recovered Fe?CA by applying a magnetic field and quantifying the unreacted Ca(2+) ions by using ion chromatography. After 30?cycles, the Fe?CA displayed strong activity, and the CO(2) capture efficiency was 26-fold higher than that of the free enzyme. Storage stability studies suggested that Fe?CA retained nearly 82?% of its activity after 30?days. Nucleation of the precipitated CaCO(3) was monitored by using polarized light microscopy, which revealed the formation of two phases, calcite and valerite, at pH?10 upon addition of serine. The magnetic nanobiocatalyst was shown to be an excellent reusable catalyst for the sequestration of CO(2.).     

Effect of pullulan/poly(vinyl alcohol) blend system on the montmorillonite structure with property characterization of electrospun pullulan/poly(vinyl alcohol)/montmorillonite nanofibers

Nanofibers of the composite of pullulan (PULL), poly(vinyl alcohol) (PVA), and montmorillonite clay (MMT) were prepared using electrospinning method in aqueous solutions. Pullulan is an interesting natural polymer for many of its merits and good properties. Because of biocompatibility and non-toxicity of PVA, it could be used in numerous fields. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), X-ray diffraction (XRD), and thermal gravimetric analysis (TGA) were done to characterize the PULL/PVA/MMT nanofibers morphology and properties. XRD patterns and FTIR data demonstrated that there were good interactions between PULL and PVA caused by possibly hydrogen bonds. Moreover, XRD data and TEM images indicated that intercalated and exfoliated MMT nanoplatelets can be obtained within the PULL/PVA/MMT nanofibers depending on the PULL/PVA blend ratios. Furthermore, the thermal stability and mechanical property (tensile strength) of PULL/PVA/MMT nanofibers could be enhanced more by exfoliated MMT nanoplatelets than intercalated structures of that nanoplatelets.     

Self-deprotonation and colorization of 1,3-bis(dicyanomethylidene)indan in polar media: a facile route to a minimal polymethine dye for NIR fluorescence imaging

Colorless 1,3-bis(dicyanomethylidene)indan is an organic acid (pK(a) ≈3.0) that turns blue in polar media owing to self-deprotonation. Moreover, its colored conjugate base shows potential as a minimal anionic polymethine dye for probing biomolecules in cells and in vivo through noncovalent complexation and near-infrared fluorescence signaling.