Different Kinds Of Functional Groups Research Articles

Ultra‐Galactocation to Sialic Acid on Tumor Cells with A Penta‐Functional Dendritic Probe for Enhanced Immune‐Killing

AbstractGlycans on tumor cell surface have significant impacts in the immune‐killing process. Here an ultra‐galactocation to sialic acid (Sia) strategy is designed to hugely introduce galactose (Gal) to Sia and on tumor cells in vivo by using a penta‐functional dendritic probe (Den@5F), which efficiently enhances the immune‐killing of tumor cells. The Den@5F contains five different kinds of functional groups, including Gal, Cy5, amino, phenylboronic acid (PBA) and 4‐(4‐(hydroxymethyl)‐2‐methoxy‐5‐nitrophenoxy) butanoate (mNB), which can be conveniently prepared through a two‐step reaction. After injecting into the tumor‐bearing mouse, Den@5F can efficiently block Sia through the specific recognition between PBA and Sia on tumor cells and hugely introduce Gal through the subsequent photo‐crosslinking between mNB and amino groups to multiply conjugate excessive Den@5Fs. The comprehensively blocked Sia can prevent the immune escape, and the hugely introduced Gal can promote the immune stimulation of the immune cells, which lead to an efficient enhancement of the immune‐killing. The proposed strategy provides a significant and promising tool to promote the clinical immunotherapy of tumor.

Ultra-Galactocation to Sialic Acid on Tumor Cells with A Penta-Functional Dendritic Probe for Enhanced Immune-Killing.

Glycans on tumor cell surface have significant impacts in the immune-killing process. Here an ultra-galactocation to sialic acid (Sia) strategy is designed to hugely introduce galactose (Gal) to Sia and on tumor cells in vivo by using a penta-functional dendritic probe (Den@5F), which efficiently enhances the immune-killing of tumor cells. The Den@5F contains five different kinds of functional groups, including Gal, Cy5, amino, phenylboronic acid (PBA) and 4-(4-(hydroxymethyl)-2-methoxy-5-nitrophenoxy) butanoate (mNB), which can be conveniently prepared through a two-step reaction. After injecting into the tumor-bearing mouse, Den@5F can efficiently block Sia through the specific recognition between PBA and Sia on tumor cells and hugely introduce Gal through the subsequent photo-crosslinking between mNB and amino groups to multiply conjugate excessive Den@5Fs. The comprehensively blocked Sia can prevent the immune escape, and the hugely introduced Gal can promote the immune stimulation of the immune cells, which lead to an efficient enhancement of the immune-killing. The proposed strategy provides a significant and promising tool to promote the clinical immunotherapy of tumor.

A Study on an Active Functional Group and Antimicrobial Properties From Rhizophora apiculata Extracts Used in Traditional Malay as Medicine

A mangrove plant known as Rhizophora apiculata is employed by Malay for treating skin diseases, diarrhea, vomiting, and nausea, as an antiseptic, for tanning, and also as fuelwood and fodder. Its large-scale use can be attributed to its high-quality timber, availability as well and the presence of a chemical named tannin that is employed for reinforcing fishing lines, nets, and ropes. The tannin content of R. apiculata's roots, bark, and leaves is regarded to be a natural inhibitor of fungal infections. This study is focused on determining the different kinds of functional groups, as well as individual phenolic compounds present in R. apiculata for identifying new bioactive compounds via decoding of the traditional values of Malay remedies. There is a high demand for such natural bioactive compounds, particularly in the healthcare and pharmaceutical markets. Alkaline fractional extracts were employed to design an analytical extraction method for R. apiculata. As per the HPLC results, there were three phenolic acids detected namely Caffeic acid, 4-Hydroxybenzoic acid, and Vanillic acid. Meanwhile, ten volatile compounds were identified by the GCTOF-MS. With regards to antibacterial activity, S. aureus, S. epidermidis, and E. coli were inhibited by R. apiculata leaf extract, while C. albicans and Fusarium sp. were inhibited by their antifungal activity.

Catalytic pyrolysis of guaiacol on Enteromorpha-based biochar: A combination of experiments and density functional theory

This study investigated the catalytic effect of Enteromorpha-based char (EPC) on guaiacol. FTIR and XPS characterization were used to confirm the functional groups of EPC, mainly oxygen-containing and nitrogen-containing. The experimental results of catalytic pyrolysis of guaiacol showed that the conversion of guaiacol without catalyst was 38.09%, and after the addition of EPC the conversion of guaiacol increased with the increase of EPC mass until complete conversion. Based on the experimental and characterization results, the catalytic mechanism of guaiacol over EPCs with different kinds of functional groups was investigated by density functional theory (DFT). According to the energy analysis of DFT, the catalytic model containing carboxyl and hydroxyl groups showed excellent adsorption performance for guaiacol. The DFT calculation result also indicates that guaiacol can be converted to phenol over EPC catalytic model with carboxyl and hydroxyl groups through elementary reactions with lower reaction energy barriers. Pyridine and pyrrole functional groups also have a good catalytic effect of lowering the energy barrier in N-containing species. This contribution provides an alternative way to gain insight into the mechanism of catalytic pyrolysis of guaiacol on EPC at both the experimental and molecular levels, and may help to design more efficient biochar catalysts.

Synthesis, structural, spectral, third order nonlinear optical and quantum chemical investigations on hydrogen bonded novel organic molecular adduct 4-(dimethylamino)benzaldehyde 4-nitrophenol for opto-electronic applications

A new molecular adduct namely, 4-(dimethylamino)benzaldehyde 4-nitrophenol (4DMAB4NP), has been synthesized through crystal engineering route by reacting 4-(dimethylamino)benzaldehyde and 4-nitrophenol in equimolar ratio. This hydrogen bonded material is found to have crystallized with centrosymmetric space group of P21/c at room temperature (RT) and making it appropriate for third order nonlinear optical (TONLO) applications. The different kinds of functional groups existing in the 4DMAB4NP were recorded and assigned through FTIR and NMR spectral studies. Thermal behavior of 4DMAB4NP was analyzed through TGA and DTA analyses. Its solubility in toluene solvent was measured to obtain high quality single crystals. The 4DMAB4NP single crystals were characterized for their laser damage threshold, TONLO properties and optical limiting behavior. Further, the dielectric behavior of 4DMAB4NP single crystal were also investigated as a function of temperature (313–343 K). In addition, density functional studies of 4DMAB4NP molecule in gaseous phase were accomplished at the B3LYP/6–311++G (d, p) basis function. Finally, 3-D Hirshfeld surface maps and the 2-D fingerprint diagram were generated for the title molecule by using crystal explorer 3.1 program.

Enhancing peat metal sorption and settling characteristics

Peat is an excellent material for metal sorption since it naturally contains different kinds of functional groups that can sorb metal cations from water. The main objective of this work was to test low-cost treatment (acid and alkali) methods for natural peat, which would improve the settling properties of peat particles while maintaining its metal removal efficiency. Particularly, the poor settling properties of peat hinder its practical application. The study revealed that NaOH-treated peat (0.1M) had excellent settling properties and could be applied in wastewater applications having mixing and settling systems without a settling aid. The superior leaching of humic and fulvic acids in alkaline treatment caused a change in morphology, making it a harder and sticky material. Moreover, the NaOH-treated (0.1M) peat was proven to be the most efficient material for nickel removal followed by the HCl-treated (0.2M) peat, citric acid-treated (0.16M) peat and water-treated peat. A higher temperature and longer time slightly increased the Ni removal efficiency with NaOH-treated peat material. The settling of HCl-treated peat was studied further using polyacrylamide flocculants (cationic, neutral, anionic). Cationic flocculants performed best and the cationic charge density also had an effect on the flocculation performance of peat particles. This study provides further evidence that peat can be applied in the treatment of metal-containing wastewaters.

Immobilization of Candida antarctic lipase B on MWNTs modified by ionic liquids with different functional groups

Multiwalled carbon nanotubes (MWNTs) were modified by imidazole-based ionic liquids with different kinds of functional groups such as alkyl, carboxyl, amino and hydroxyl. The supports were used to immobilize Candida antarctic lipase B (CALB) and the influence of different functional groups of ionic liquids on enzymatic properties was investigated by the hydrolysis reaction of triacetin. The results revealed that the functionalization process did not destroy the structural integrity of MWNTs, and the enzymatic properities of CALB which immobilized on the MWNTs modified by ionic liquids with different kinds of functional groups were all improved. The hydroxyl functionalized ionic liquids which exhibited the best enzymatic properities was selected to investigate the effects of different carbon chain length on the enzymatic properties of immobilized CALB. Among them, CALB which immobilized on MWNTs modified by hydroxyl functionalized ionic liquid with suitable chain length (MWNTs-IL(8C)-OH-CALB) had the highest specific activity, with a specific activity of 18.11 times that of MWNTs-CALB. Furthermore, it also presented best thermal stability and reusability. The residual activity of MWNTs-IL(8C)-OH-CALB held over 64.01% of the initial activity after being incubated for 20min at 70°C, and the residual activity was 85.56% after 4 cycles of use.

Effects of functional groups on the tribological properties of hairy silica nanoparticles as an additive to polyalphaolefin

Hairy silica nanoparticles with different kinds of functional groups were prepared and dispersed into polyalphaolefin, the effects of the functional groups on the tribological properties of the hairy silica nanoparticles were investigated.

S‐layer proteins as an immobilization matrix for aptamers on different sensor surfaces

S‐layer proteins provide a biocompatible environment with different kinds of functional groups, perfect for the sequential coupling of any kind of biofunctional molecule. In addition, their nanostructure and their ability to crystallize on surfaces in a nanometer‐thick monolayer ensure a regular arrangement of these molecules on solid supports. In this work, a thrombin‐binding aptamer and an ofloxacin‐binding aptamer were coupled with different chemical crosslinkers to S‐layer proteins using them for defined immobilization. S‐layer protein monomers and paracrystalline S‐layers were successfully modified with the thrombin‐binding aptamer. However, S‐layer protein monomers were not able to crystallize after aptamer modification and showed no thrombin binding during random surface attachment. In contrast, aptamers linked to an intact S‐layer in suspension or an S‐layer coating were still functional. The modification rate of S‐layers with the thrombin‐binding aptamer was estimated with one aptamer to two unit cells (unit cell = four monomers). Verification of the functionality of both aptamers through target binding after S‐layer‐immobilization on solid supports was proven by laser‐induced fluorescence spectroscopy (LIFS), resonant mirror sensor (IAsys), and quartz crystal microbalance with dissipation monitoring (QCM‐D), respectively. Hence, this study presents S‐layer proteins as an interesting alternative to existing immobilization matrices for recognition biomolecules.

Organic-Inorganic Hybrid Polymers as Adsorbents for Removal of Heavy Metal Ions from Solutions: A Review.

Over the past decades, organic-inorganic hybrid polymers have been applied in different fields, including the adsorption of pollutants from wastewater and solid-state separations. In this review, firstly, these compounds are classified. These compounds are prepared by sol-gel method, self-assembly process (mesopores), assembling of nanobuilding blocks (e.g., layered or core-shell compounds) and as interpenetrating networks and hierarchically structures. Lastly, the adsorption characteristics of heavy metals of these materials, including different kinds of functional groups, selectivity of them for heavy metals, effect of pH and synthesis conditions on adsorption capacity, are studied.

Kinetic estimation of hydrogen isotope exchange reaction between tritiated-water (HTO) vapor and each amino acid in a heterogeneous system

The hydrogen isotope exchange reaction between HTO vapor and each amino acid has been observed in order to establish a method of estimation of the internal exposure of organically bound tritium in a heterogeneous system at 25∼70°C. Rate constants (k) for the amino acids have been obtained by applying the A″-McKay plot method. Using these k values, Arrhenius plots for both the COOH and NH2 groups are drawn, and linearity was obtained over the range of 25∼70°C. Comparing the rate constants, the following four statements can be made regarding the T-for-H exchange reaction. (1) The reactivity of the functional groups in amino acids increases with increasing temperature. (2) Applying Taft's equation, the ratio of polar effect to steric effect is 2:8 in the COOH group and 9:1 in the NH2 group at 25°C. (3) The A″-McKay plot method is useful for studying the reactivity of materials, not only with one (or the same kind of) functional group(s) but also with two different kinds of functional groups. (4) The method used in this work may be useful to investigate the behavior of organically bound tritium, quantitatively.

A facile in situ hydrophobic layer protected selective etching strategy for the synchronous synthesis/modification of hollow or rattle-type silica nanoconstructs

A novel and general in situ hydrophobic shell-protected selective etching strategy has been developed to synchronously synthesize and modify hollow mesoporous silica nanoparticles (HMSNs) and rattle-type mesoporous silica nanoparticles (RMSNs) with well-defined morphology, effectively avoiding the drawbacks of post-modification. The key point of the strategy lies in the hydrophilicity differences between the pure silica inner core and the organic hybrid silica shell, which results in the preferential etching of the pure silica inner core. Except that amino group functionalized HMSNs (amino-HMSNs) can be synthesized via this strategy, it can be readily applied for the synthesis of HMSNs and RMSNs synchronously grafted with different kinds of functional groups by employing other silane coupling agents, directly indicating the generality of this strategy. Furthermore, adding no additional reduction agents, the amino-HMSNs can be regarded as nanoreactors, and a distinctively heterogeneous rattle-type structure, Au@HMSN/Au, with an entrapped size-tunable Au nanoparticle and some small Au nanocrystals embedded in the hollow cavity and shell of each nanoparticle, respectively, is obtained. As hybrid ultrasound contrast agents (UCAs), unlike micro-sized organic UCAs merely confined to blood pool imaging, the as-synthesized nano-sized amino-HMSNs can achieve excellent in vitro ultrasound imaging, and potentially be applied in cell-level imaging. More importantly, relying on the process merits of our strategy, such as the doping of silane coupling agents and no calcination treatment, amino-HMSNs exhibit enhanced ultrasound imaging to some certain extent compared to the calcined ones.

Single‐Side Organically Functionalized Anderson‐Type Polyoxometalates

Polyoxometalate (POM)-based organic–inorganic hybrid materials have attracted extensive attention in the last ten years due to their potential applications in catalysis, nonlinear optics, photovoltaic, and self-assembly research. Currently, trisalkoxo tripodal ligand (Tris)-functionalized Lindqvist-, Anderson-, and Dawson-type POMs show high stability and varied functionalities. Zubieta et al. used Tris ligands to stabilize macro-POM clusters and to functionalize hexavanadate. The functionalized hexavanadate was further developed by Hill and co-workers for the construction of metal–organic frameworks, which can function as highly efficient heterogeneous catalytic materials. Due to the high reactivity of vanadate, vanadium-containing Dawsontype POMs were observed to be capped by only one Tris ligand. In particular, after Hasenknopf et al. had established the synthesis of Tris derivatives of Anderson-type POMs in 2002, the groups of Cronin and Hasenknopf introduced different kinds of functional groups to the system through further organic reactions. The resulting materials show interesting functions including high biological activity against cells, photocatalytic properties, and interesting selfassembly behavior. Due to their high symmetry (D3d), both sides of Anderson-type POMs are easily functionalized simultaneously by Tris ligands during their synthesis, which seems to be an unquestionable fact (Figure 1), and there has never been any report on a single-sided functionalized Anderson-type POM with Tris. Herein, we report the synthesis and characterization of Anderson-type POMs with only one side functionalized by a Tris ligand, which not only afforded asymmetric POM-based hybrid materials for further research, but also uncovered more structural and reactive properties of Anderson-type POMs, and the reaction mechanism for the functionalization of POMs with Tris. In the previous protocol, to synthesize the double-sided functionalized Anderson-type POMs, octamolybdate, a salt of the central heteroatom, and organic ligands (Tris) were mixed in an organic solvent, such as acetonitrile, and the final products were obtained after heating to reflux for approximately 16 hours, which is a classical one-pot reaction. However, our new protocol to synthesize the single-side organically functionalized Anderson-type POM, [(C4H9)4N]5{H7ACHTUNGTRENNUNG[HOCH2C ACHTUNGTRENNUNG(CH2)3 ACHTUNGTRENNUNG(CrO6)Mo6O18]2} (1), is a two-step aqueous reaction with high yield through the direct functionalization of the parent Anderson-type POM, [CrMo6O18(OH)6] 3 . Compound [CrMo6O18(OH)6] 3 was first synthesized according to Perloff s method reported in 1970. Pentaerythritol was then added to the resulting aqueous solution of [CrMo6O18(OH)6] 3 , and the mixture was refluxed at once for a prolonged time to finish the esterification. Interestingly, the reaction is of high yield and high selectivity for the mono Tris-functionalized product 1, probably due to the hierarchical synthesis protocol and aqueous reaction media (see the Experimental Section). In the preparation reaction, a single-side-functionalized Anderson-type POM is obtained in high yield (based on Mo), even when the ratio of Tris to the parent Anderson-type POM is two or much higher than two. Therefore, the selectivity for producing such single-sided species might be related to the aqueous environment. [a] P. Wu, P. Yin, Dr. J. Zhang, Dr. J. Hao, Dr. Z. Xiao, Prof. Dr. Y. Wei Department of Chemistry, Tsinghua University Beijing, 100084 (P.R. China) Fax: (+86)10-6277-1149 E-mail : yinpanchao@tsinghua.org.cn yonggewei@tsinghua.edu.cn [b] P. Wu Institute of POM-based Materials Key Laboratory of Fermentation Engineering (Ministry of Education) Hubei University of Technology Wuhan, 430068 (P.R. China) [c] Prof. Dr. Y. Wei Key Laboratory of Cluster Science (Beijing Institute of Technology) Ministry of Education of China Beijing, 100081 (P.R. China) Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.201101552. Figure 1. Molecular structures of: a) unfunctionalized and b) bifunctionalized Anderson-type POMs. Color code: Mo: large black sphere; Cr: central gray sphere; O: small black sphere; C: large gray sphere; H: small gray sphere; X= functional group: -CH2OH, -NH2, -CH3, or -NO2.

A novel route to substituted poly(vinyl pyrrolidone)s via simple functionalization of 1-vinyl-2-pyrrolidone in the 3-position by ring-opening reactions

A general synthetic approach is described that allows to obtain novel 1-vinyl-2-pyrrolidone (VP) derivatives with different kinds of functional groups in its 3-position in a one-pot reaction. The strategy used to achieve this goal is the reaction of the carboxamide anion of 1-vinyl-2-pyrrolidone with cyclic precursors of these functionalities. While the driving force for the reactions of three-membered rings is their high annular tension, it is shown here that larger heterocycles can be opened with good yield when additional electron-withdrawing groups are present in the ring. This leads to VP with longer spacer groups between the functionality and the future polymeric main chain. Furthermore, the high versatility of this procedure is demonstrated by the preparation, for the first time, of VP modified with amine or sulfonic functionalities that allow to prepare the corresponding aminated and sulfonated PVPs.

Structure–property relationship in chitosan‐based biopolymer/montmorillonite nanocomposites

Three kinds of chitosan-based biopolymer/montmorillonite (MMT) nanocomposites have been prepared by an exfoliation–adsorption method. The structure of MMT is tailored by the functional groups of the polymer matrix. Chitosan/MMT nanocomposites form intercalated-and-flocculated structures, whereas with the introduction of carboxymethyl into chitosan, N,O-carboxymethyl chitosan/MMT nanocomposites form even stronger flocculated structures. On the other hand, direct quaternization of the amino group of chitosan to form N,N,N-trimethyl chitosan chloride/MMT nanocomposites gives a nearly exfoliated structure. The nanodispersion of MMT in the biopolymer matrices affects the thermal degradation mechanism in different ways corresponding to the different kinds of functional groups that are introduced into the chitosan matrix.

Reactivity of sulfonic acid group and estimation of its substituent-effect in T-for-H exchange reaction

The hydrogen-isotope exchange reaction (T-for-H exchange reaction) between each solid material having two different kinds of functional groups and HTO vapor has been observed at several temperatures. Solid materials used were monosubstituted aminobenzenes. The rate constant (k) for each functional group was obtained by applying both the A"-McKay plot and the date obtained. Comparing these k values quantitatively leads to the followings: (1) the A"-McKay plot is useful in obtaining the reactivity of the compounds having two different kinds of functional groups; (2) as to m-aminobenzenesulfonic acid, the reactivity of the SO3H group is about 6.6-8 times larger than that of the NH2 group, and the temperature dependence of the reactivity of the SO3H group is also larger than the dependence of that of the NH2 one; (3) the reactivity of the NH2 group of some kinds of monosubstituted aminobenzenes may follow the Hammett rule; (4) the substituent constant (s) of SO3H group is estimated as follows: sm is 0.38, and sp is 0.64; (5) the substituent-effect of SO3H group is generally larger than that of other substituents; and (6) the subsutituent-effect unknown can be estimated by applying both the Hammett rule and A"-McKay plot.

Estimation of the dissociation constants for functional groups on modified and unmodified silica gel supports from the relationship between electroosmotic flow velocity and pH.

Electroosmotic volume flow was directly observed in a simple instrument consisting of 1 cm long a home-made support, packed between two polyethylene frits in the polypropylene tube. Equations relating electroosmotic flow (EOF) velocity and pH for two functional groups on the surface of the solid materials were developed. With these equations, we can estimate the dissociation constants of two different kinds of functional groups on modified silica gel materials simultaneously. The dissociation constants of silanol groups, benzene sulfonic acid groups, and alkyl quaternary ammonium groups on the modified and unmodified silica gel supports were estimated. The estimated pK values of the silanol groups on the silica gel and modified silica gel surfaces are between 4.0 and 4.3. The estimated pK values of the benzene sulfonic acid groups and alkyl quaternary ammonium groups on the surface of the modified silica gel are 2.6 and 8.6, respectively.

T-for-H exchange reaction between HTO vapor and two functional groups in an aromatic compound in a gas-solid system

The hydrogen-isotope exchange reaction (T-for-H exchange reaction) between HTO vapor and an aromatic compound having two different kinds of functional groups has been observed at several temperatures. The rate constant (k) for each functional group in the T-for-H exchange reaction was obtained by using both theA″-McKay plot method and the data observed. Comparing thesek with each other has led to the following four conclusions in the T-for-H exchange reaction. (1) The reactivity of both the COOH and OH groups increases with a rise in temperature. (2) As to the degree of the effect of the COOH group on the reactivity of monosubstituted phenols, the degree inp-hydroxybenzoic acid is greater than that inm-hydroxybenzoic acid. (3) The HAMMETT rule is useful for estimating the reactivity of a certain aromatic compound. (4) TheA″-McKay plot method is also useful not only investigating the reactivity of the compounds having one kind of functional group, but also doing the reactivity of the compounds having two different kinds of functional groups.

Analysis of the reactivity of materials having two different kinds of functional groups using the A″-McKay plot method

The hydrogen-isotope exchange reaction between HTO vapor (as a gaseous material) andp-aminophenol (or α-alanine) (as a solid material) having two different kinds of functional groups, has been studied to reveal the reactivity of the compounds. The reaction has been analyzed by the A″-McKay plot method and the rate constants (k) for each group have been obtained. Comparison ofk leads to the following: (1) the effect of the NH2 group inp-aminophenol on the reactivity is greater than that in α-alanine, and (2) the reactivity of compounds having two different kinds of functional groups can be analyzed by the A″-McKay plot method only.

Comparison of the Reactivity of the Materials Having Two Different Kinds of Functional Groups by Applying Hydrogen-Isotope Exchange Reaction

Article Comparison of the Reactivity of the Materials Having Two Different Kinds of Functional Groups by Applying Hydrogen-Isotope Exchange Reaction was published on February 1, 1995 in the journal Radiochimica Acta (volume 68, issue 2).