Determination of human serum albumin and γ-globulin in a control serum solution by near-infrared spectroscopy and partial least squares regression

Near infrared (NIR) spectra in the 1300– 1850 nm region were measured for control serum solutions containing both albumin and γ-globulin of various concentrations. Partial least squares two (PLS2) regression was applied to the NIR spectra to determine simultaneously the concentrations of both proteins. For albumin, the correlation coefficient (R) of 0.988, the standard error of calibration (SEC) of 1.61 g/L, the standard error of prediction (SEP) of 1.29 g/L, the relative standard deviation (RSD) of 0.026 and the ratio of standard deviation of reference data in prediction to SEP (RPD) of 12.2 were obtained. For γ-globulin, the corresponding values were 0.997, 1.36 g/L, 1.35 g/L, 0.0365 and 8.66, respectively. The regression coefficients (RCs) of PLS factors were compared between albumin and γ-globulin, and the observed differences in the RCs were discussed based upon the differences in the hydration between albumin and γ-globulin. In order to explore the effects of various metabolites such as glucose, and cholesterol on the chemometrics models, the RCs for albumin and γ-globulin in the control serum solutions were also compared with those for albumin and γ-globulin in phosphate buffer solutions previously studied. The results of our experiments show that NIR spectroscopy with the use of PLS2 regression has considerable promise in nondestructive determination of the concentrations of blood serum proteins. Received: 31 December 1997 / Revised: 9 April 1998 / Accepted: 27 April 1998     

An efficient synthetic methodology of chiral isoquinuclidines by the enantioselective Diels-Alder reaction of 1,2-dihydropyridines using chiral cationic palladium-phosphinooxazolidine catalyst

High purity chiral isoquinuclidines (97% ee) were obtained from the enantioselective Diels-Alder reaction of 1-phenoxycarbonyl-1,2-dihydropyridine with 1-benzyl-2-acryloylpyrazolidin-3-one using chiral cationic palladium-phosphinooxazolidine (Pd-POZ) catalyst. The obtained DA adduct was easily converted to the chiral piperidine derivative bearing three stereogenetic centers in the structure.     

Self-assembled metal colloid films: two approaches for preparing new SERS active substrates

In this paper, we propose two new approaches for preparing active substrates for surface-enhanced Raman scattering (SERS). In the first approach (method 1), one transfers AgI nanoparticles capped by negatively charged mercaptoacetic acid from a AgI colloid solution onto a quartz slide and then deoxidizes AgI to Ag nanoparticles on the substrate. The second approach (method 2) deoxidizes AgI to Ag nanoparticles in a colloid solution and then transfers the Ag nanoparticles capped by negatively charged mercaptoacetic acid onto a quartz slide. By transfer of the AgI/Ag nanoparticles from the colloid solutions to the solid substrates, the problem of instability of the colloid solutions can largely be overcome. The films thus prepared by both approaches retain the merits of metal colloid solutions while they discharge their shortcomings. Accordingly, the obtained Ag particle films are very suitable as SERS active substrates. SERS active substrates with different coverages can be formed in a layer-by-layer electrostatic assembly by exposing positively charged surfaces to the colloid solutions containing oppositely charged AgI/Ag nanoparticles. The SERS active substrates fabricated by the two novel methods have been characterized by means of atomic force microscopy (AFM) and ultraviolet-visible (UV-vis) spectroscopy. The results of AFM and UV-vis spectroscopy show that the Ag nanoparticles grow with the increase in the number of coverage and that most of them remain isolated even at high coverages. Consequently, the surface optical properties are dominated by the absorption due to the isolated Ag nanoparticles. The relationship between SERS intensity and surface morphology of the new active substrates has been investigated for Rhodamine 6G (R6G) adsorbed on them. It has been found that the SERS enhancement depends on the size and aggregation of the Ag particles on the substrates. Especially, we can obtain a stronger SERS signal from the substrate prepared by method 1, implying that for the metal nanoparticles capped with stabilizer molecules such as mercaptoacetic acid, the in situ deoxidization in the film is of great use in preparing SERS active substrates. Furthermore, we have found that the addition of Cl- into the AgI colloid solution changes the surface morphology of the SERS active substrates and favors stronger SERS enhancement.     

A new synthetic approach to the bicyclo[5.3.1]undecane ring system in taxanes

The bicyclo[5.3.1]undecane derivative 19, which was referred to the A,b ring system of taxane diterpenes, was synthesized by a base-induced fragmentation reaction of the tricyclic diol monomesylate 18 derived highly stereoselectively from 5-methyl-1,3-cyclohexadione.     

NEAR-INFRARED FOURIER-TRANSFORM RAMAN STUDY OF CHLOROPHYLL a IN SOLUTIONS

Abstract— The 1064 nm excited Fourier-transform (FT) Raman spectra have been measured for chlorophyll a (Chl- a ) in various solutions. Features of the obtained spectra are largely different from those of Soret-resonant Raman spectra of Chl- a . For example, a band due to the C=0 stretching mode of the 13-keto group is much stronger in the former than in the latter. Although the excitation wavelength is rather far from that of the Qy absorption of Chl- a , notable enhancements of bands due to the C=O stretching mode of the 13¹-keto group and to the C=C stretching mode of the vinyl group and those in the 1250–600 cm^-1 region suggest that the 1064 nm-excited Raman spectra of Chl- a are preresonance enhanced via the Qy band. Some of the marker bands for the coordination number of the central Mg atom, which have been used in the visible-excited resonance Raman spectra, are not valid in the 1064 nm-excited Raman spectra. Instead, new marker bands are found in the latter. The 1064-nm excited Raman spectra of Chl- a in a hydrated hexane solution reveal that the dehydrated oligomer of Chl- a as well as Chl- a -water micelles coexist in the solution. They also suggest that the size of the oligomer is considerably larger and the hydrogen bonding of the 13¹-keto group in the oligomer is weaker than that in the micelles.     

Quantitative evaluation of weak nonbonded Se...F interactions and their remarkable nature as orbital interactions

To evaluate weak intramolecular nonbonded Se...F interactions recently characterized for a series of o-selenobenzyl fluoride derivatives (Iwaoka et al., Chem. Lett. 1998, 969-970), the temperature dependence of the nuclear spin coupling between Se and F (J(Se...F)) was investigated for 2-(fluoromethyl)phenylselenenyl cyanate (1a) and bis[2-(fluoromethyl)phenyl] diselenide (1e) in CD2Cl2 and CD3CN. A significant increase in the magnitude of J(Se...F) was observed for both 1a and 1e upon lowering temperature, whereas the values of J(Se...F) for the corresponding trifluoromethyl compounds slightly reduced or remained unchanged at low temperatures. Application of the rapid equilibrium model between two possible conformers revealed that conformer A with an intramolecular Se...F interaction is more stable in enthalpy (DeltaH) by 1.23 kcal/mol for 1a (in CD2Cl2) and by 0.85 and 0.83 kcal/mol for 1e (in CD2Cl2 and CD3CN, respectively) than conformer B, which does not have close Se...F contact. The negligible solvent effects for 1e suggested marginal electrostatic nature of the Se...F interactions. Instead, importance of the n(F) -->sigma*(Se-X) orbital interaction was suggested by quantum chemical (QC) calculations and the natural bond orbital (NBO) analysis.     

Catalytic reactions of oxetanes with protonic reagents and aprotic reagents leading to novel polymers

This paper reports new addition reactions of oxetanes with certain protonic reagents such as carboxylic acid, phenol, and thiol, and with certain aprotic reagents such as acyl chloride, thioester, phosphonyl dichloride, silyl chloride, and chloroformate using quaternary onium salts as catalysts. The kinetic study of the addition reactions of oxetanes was also investigated. These new addition reactions were applicable to the synthesis of new polymers. These polyaddition systems could also construct both polymer main chains and reactive side chains. The alternating copolymerization of oxetanes with carboxylic anhydride was performed. Furthermore, it was found that anionic ring‐opening polymerization of oxetanes containing hydroxy groups proceeded to afford the hyperbranched polymer (HBP) with an oxetanyl group and many hydroxy groups at the ends of the polymer chains. Alkali developable photofunctional HBPs were synthesized by the polyaddition of bis(oxetane)s or tris(oxetane)s, and their patterning properties were examined, too. The photo‐induced cationic polymerization of the polymers with pendant oxetanyl groups and the thermal curing reactions of polyfunctional oxetanes (oxetane resins) were also examined to give the crosslinking materials quantitatively. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 709–726, 2007     

Regioselective synthesis of triiodo-o-carboranes and tetraiodo-o-carborane

3,6-Diiodo-o-carborane 3, 3,6,9-triiodo-o-carborane 5, 3,9,12-triiodo-o-carborane 6 and 3,6,9,12-tetraiodo-o-carborane 7, which are suitable building blocks for supramolecular assemblies and carboracycles, were regioselectively synthesized by means of electrophilic iodination and introduction of iodine atoms via reconstruction of the o-carborane cage.     

Synthesis of star polymer by atom transfer radical polymerization with resorcinol‐core multifunctional initiator: The construction of nanocapsule via hydrolysis and olefin metathesis reaction of the obtained star polymer

Olefin group‐carrying styrene, 1‐but‐3‐enyl‐4‐vinylbenznene (BVB), was polymerized via atom transfer radical polymerization (ATRP) initiated from C‐methylcalix [4]resorcinarene‐based multifunctional initiator (CRA‐bib) at low conversion to produce star polymer [poly(BVB)] with narrow molecular weight distribution (M_w/M_n < 1.35). The copolymerization of styrene (St) with poly(BVB) (M_n = 11,000, M_w/M_n = 1.23) as a macroinitiator afforded star block copolymer [poly(BVB‐b‐St)] with M_n = 35,000 and M_w/M_n = 1.44. The BVB layer of poly(BVB‐b‐St), located between the St shell and the CRA core, was crosslinked by olefin metathesis reaction of olefin groups o the BVB moieties. The removal of the CRA core of the crosslinked poly(BVB‐b‐St) by hydrolysis using KOH as a base gave polymeric hollow sphere [poly(cored crossBVB‐b‐St)] with good solubility in organic solvents. The morphological structure of the poly(cored crossBVB‐b‐St) showed spherical aggregates in THF by scanning electron microscopy (SEM). Furthermore, the nanocapsule structure of poly(cored crossBVB‐b‐St) with hollow spheres was found to be observed by transmission electron microscopy (TEM). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4879–4888, 2008     

Overgrowth of GaN on Be-doped coalesced GaN nanocolumn layer by rf-plasma-assisted molecular-beam epitaxy—Formation of high-quality GaN microcolumns

GaN crystals were overgrown on GaN nanocolumn platforms with a Be-doped coalesced layer by rf-plasma-assisted molecular-beam epitaxy (rf-MBE). The overgrown GaN included large micrometer-scale hexagonal columnar crystals. These microcrystals were named ‘microcolumns’ and showed high optical properties comparable to those of GaN bulk crystals grown by hydride vapor phase epitaxy (HVPE).