SiWei Liu

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Name: 刘四委; Liu, SiWei
Organization: Sun Yat-sen University , China
Department:
Title: Associate Professor(PhD)

TOPICS

Co-reporter:
Chinese Journal of Chemistry 2017 Volume 35(Issue 3) pp:335-340
Publication Date(Web):2017/03/01
DOI:10.1002/cjoc.201600689
AbstractAs a paramagnetic metal ion, Cu(II) is challenging to be detected by conventional fluorescence sensor because of its unselective paramagnetic quenching effects on common fluorophores. By combining catechol with tetraphenylethene, a typical aggregation-induced emission (AIE) moiety, we have successfully synthesized a new kind of catechol, the dopa-AIE compound. Due to the properties of AIE core, the catechol has the “turn on” mechanism as a fluorescence chemosensor. Specifically, the new catechol has the unique detection selectivity on Cu(II) in solution. The fluorescence intensity has the maximum value when the molar ratio of the catechol to Cu(II) is 1∶1. Before and after this point, the fluorescence intensity shows a linear relationship with the copper ion concentration, increasing or decreasing. Thus, the quantitative calculation for Cu(II) or the dopa-AIE compound could be done according to this response process.
Co-reporter:Yupeng Wu;Yangchun Tao;Kuan Cai;Yi Zhang;Zhenguo Chi;Jiarui Xu;Yen Wei
Chinese Journal of Chemistry 2015 Volume 33( Issue 12) pp:1338-1346
Publication Date(Web):
DOI:10.1002/cjoc.201500728

Abstract

Two triblock polymers, tetraaniline-block-poly(N-isopropyl acrylamide)-block-poly(hydroxyethyl acrylate) (TA-b-PNIPAM-b-PHEA) and TA-b-PHEA-b-PNIPAM, were synthesized with unambiguous structure by a two step method. The difference of these two diblock polymers is the connection order of carboxyl group to block, e.g., carboxyl group to PNIPAM block for PNIPAM-b-PHEA and to PHEA block for PHEA-b-PNIPAM. Secondly, block tetraaniline was linked to the diblock polymer through amidation to yield the corresponding triblock copolymer. Both of them have almost the identical chemical compositions. The only difference is the connection order of each block in the triblock polymers. When they were self-assembled at 45°C in a suitable solution, both of their aggregates have spherical shape with slight defects on their surface with the average diameter of about 400 nm. However, when their aggregate dispersion was cooled down to 20°C, only TA-b-PHEA-b-PNIPAM's morphology changed, forming worm-like aggregates with the diameter of about 100–200 nm transformed from spherical aggregates. Both amphiphilic property and position of each block in this triblock copolymer are very essential for this morphology transformation. Since the worm-like aggregates presented here by our group have hollow structure inside, its controlled release properties for doxorubicin were evaluated. Drug release experiment indicated that along with the temperature changes, the rearrangement of the intermediate layer structure caused morphology change in aggregate, thus accelerating the speed of drug release.

Co-reporter:Yupeng Wu, Siwei Liu, Yangchun Tao, Chunping Ma, Yi Zhang, Jiarui Xu, and Yen Wei
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 3) pp:1470
Publication Date(Web):January 22, 2014
DOI:10.1021/am404696u
A series of amphiphlic diblock polymers, tetraaniline block with different length of poly(N-isopropylacrylamide) (TA-b-PNIPAM), have been successfully synthesized. In a suitable solution, the as-synthesized diblock polymers can form stable large compound vesicles (LCVs) with multiple bimolecular-layer structure through self-assembly. These factors, such as the block length, different organic solvent, solvent ratio, pH value, temperature, and voltage, which affect the morphology and properties of the assembled aggregates, are systematically investigated. When the degree of polymerization of PNIPAM block is close to 10, the as-synthesized diblock polymer may form stable LCVs with the uniform size as well as few defects in the mixed solvent of dimethylformamide/water (v/v = 3:7). The assembled LCVs possess the properties of triple-responsive capacity on temperature, pH, and voltage. Variation in any of these factors can cause some changes in the morphology of LCVs. The drug release properties for doxorubicin (DOX) loaded by LCVs affected by temperature, voltage, and different pH values have been investigated. It is interesting that the structure of LCVs can be destructed completely by applying a voltage at 0.6 V. With such an advantage, the drugs loaded by the LCVs could burst release into designated place by using appropriate circuit design or instrument, thus achieving maximum efficacy of the loaded drugs or other bioactive molecules without any unnecessary chemical substances added. This approach allows us to concentrate more on material design aspects only, without regard to the complex targeting issue which is the biggest obstacle of such materials in practical applications.Keywords: drug release; large compound vesicle; multiresponse; pinpoint targeting; self-assembly; tetraaniline diblock polymer;
Co-reporter:Siwei Liu;Feng Zhang;Yi Zhang ;Jiarui Xu
Chinese Journal of Chemistry 2013 Volume 31( Issue 10) pp:1315-1320
Publication Date(Web):
DOI:10.1002/cjoc.201300638

Abstract

A series of linear poly glycidol copolymers, tethering with both alkene and hydroxyl groups, were prepared by a combination of anionic ring-opening polymerization (ROP) using specific reactions of ethoxy ethyl glycidyl ether (EEGE) and allyl glycidyl ether (AGE) firstly, and subsequently removal of the protection group of glycidol in EEGE to achieve the linear copolymer pendant with both hydroxyl groups and double bonds. The EEGE/AGE monomer reactivity ratio is measured to be 3.30/1.13. The chemical compositions of the as-synthesized polymers were characterized by 1H NMR and GPC, and the glass transition temperatures (Tg) of as-synthesized polymers were determined by DSC. The final copolymers have abundant double bonds and hydroxyl as side groups. Furthermore, the ratio of the double bonds to hydroxyl groups can be controlled by the ratio of the starting materials in a wide range.

Co-reporter:Feng Zhang, Siwei Liu, Yi Zhang, Zhenguo Chi, Jiarui Xu and Yen Wei  
Journal of Materials Chemistry A 2012 vol. 22(Issue 33) pp:17159-17166
Publication Date(Web):27 Jun 2012
DOI:10.1039/C2JM32647G
A poly(ethylene glycol) (PEG) derivative, poly(ethoxyethyl glycidyl ether-co-allyl glycidyl ether)-g-catechol (PEAC), has been synthesized. With vinyl side groups, this polymer can readily undergo further thiol–ene photochemical reactions. Due to the existence of the pendant catechol functional groups, PEAC can be attached onto the surface of various substrates, including hydrophilic (e.g. glass), metallic (e.g. titanium) and hydrophobic (e.g. polytetrafluoroethylene) substrates. Various thiols can be subsequently immobilized onto the PEAC-modified surfaces through the thiol–ene reaction. The surface PEGylation and further thiol immobilization have been verified by static water contact angle, ellipsometry and XPS measurements. The results of 3T3 fibroblast cell adhesion assays show that the PEAC-modified substrates have good biological anti-fouling ability. Thus this material would be used on medical implants and diagnostic devices, as well as other applications where the reduction of surface fouling is desired. More interestingly, the PEAC-modified surface is cell-repelling but exhibits excellent cell adhesion ability after further attachment of 3-mercaptopropionic acid. It would thus allow for designing and adjusting the cell adhesion ability of the substrates. This versatile, substrate-independent approach should be of significance for the development of new materials in the field of cell culture and tissue engineering.
Co-reporter:Feng Zhang;Yi Zhang;Jiarui Xu;Yen Wei
Chinese Journal of Chemistry 2012 Volume 30( Issue 10) pp:2275-2280
Publication Date(Web):
DOI:10.1002/cjoc.201200507

Abstract

Four kinds of poly(ethylene glycol) (PEG) derivatives with the similar backbone and different side groups have been synthesized successfully. When both catecholamine and double bond are tethered to polymer backbone, i.e., the PEG backbone, simultaneously, the polymer can accelerate the curing speed of ethyl α-cyanoacrylate (commercially available as 502) greatly under the same conditions (the curing time of such system is no more than 5 s). Probably this is due to the autoxidation of catecholamines. Through the redox-cycling, catecholamines can produce, collect free radicals, and thus initiate the free radical polymerization. Due to the fast-curing of such material when mixed with α-cyanoacrylate, we could design and develop a new bicomponent super bioglue used in the dentistry or other bioenvironment requiring super fast settlement for further surgical operations.

Co-reporter:Yi Zhang, Shanxiong Xiao, Qianyi Wang, Siwei Liu, Zhengping Qiao, Zhenguo Chi, Jiarui Xu and James Economy  
Journal of Materials Chemistry A 2011 vol. 21(Issue 38) pp:14563-14568
Publication Date(Web):18 Aug 2011
DOI:10.1039/C1JM12450A
Novel thermally conductive, insulated polyimide nanocomposite films are reported here for microelectronics applications. A thermally conductive, insulated inorganic nanolayer of AlO(OH) was successfully coated onto the surface of MWCNTs, which, on the one hand, can effectively avoid the formation of MWCNT electrically conductive networks in the PI matrix and, on the other, can provide the advantage of excellent thermal conductivity properties of the MWCNTs.
Co-reporter:Siwei Liu;Yi Zhang;Jiarui Xu
Chinese Journal of Chemistry 2011 Volume 29( Issue 5) pp:1036-1040
Publication Date(Web):
DOI:10.1002/cjoc.201190176

Abstract

A series of polyureas were synthesized through the reaction of aniline trimer with toluene-diisocyanate, diphenylmethane-4,4′-diisocyanate, and hexamethylene-1,6-diisocyanate, respectively. The chemical structure of these polyureas was characterized and verified by FT-IR, 1H NMR, elemental analysis, UV, XRD and CV. The conductivity of these polyureas ranged from 10−7 to 10−6 S/cm measured by four-point-probe instrument. Compared to the standalone aniline trimer, the stability (thermal stability and electrochemical stability), response range and sensitivity of these polyureas are enhanced. The sensitivity of these polyureas DMF solution to pH value is superior to that of the standalone aniline trimer. The color of the polyureas DMF solution is greatly depended on pH value and the color change process is reversible, whenever from base to acid or from acid to base. These enhancements may give these polyureas more opportunities in order to be used as sensor materials.

Co-reporter:Feng Zhang, Siwei Liu, Yi Zhang, Jiarui Xu, Zhenguo Chi
International Journal of Adhesion and Adhesives 2011 Volume 31(Issue 6) pp:583-586
Publication Date(Web):September 2011
DOI:10.1016/j.ijadhadh.2011.06.002
In this work, we graft polyacrylate with 3,4-dihydroxyphenylalanine, a functionality alike adhesive protein in mussels, to obtain a mussel-mimic polyacrylate with good adhesive property and interesting nano-patterns during adhesion. The chemical structure of the product is confirmed by 1H NMR that dopamine is grafted onto the polymer. The analysis of the tensile strength test reveals that the adhesive is improved more than 2 times, from 53 to 124 KPa, when polyacrylate grafted by dopamine. The analysis of the static water contact angle suggests that the hydrophilic of the as-synthesized final polymer is enhanced. It is very interesting to observe that such an adhesive material can form nano-patterns on the adhesion interface during bonding, at about 100 nm in diameter each contact point, which something look like the gecko foot structure. This structural feature maybe related to the increasing adhesive properties of such materials.
Co-reporter:Yi Zhang, Shanxiong Xiao, Qianyi Wang, Siwei Liu, Zhengping Qiao, Zhenguo Chi, Jiarui Xu and James Economy
Journal of Materials Chemistry A 2011 - vol. 21(Issue 38) pp:NaN14568-14568
Publication Date(Web):2011/08/18
DOI:10.1039/C1JM12450A
Novel thermally conductive, insulated polyimide nanocomposite films are reported here for microelectronics applications. A thermally conductive, insulated inorganic nanolayer of AlO(OH) was successfully coated onto the surface of MWCNTs, which, on the one hand, can effectively avoid the formation of MWCNT electrically conductive networks in the PI matrix and, on the other, can provide the advantage of excellent thermal conductivity properties of the MWCNTs.
Co-reporter:Feng Zhang, Siwei Liu, Yi Zhang, Zhenguo Chi, Jiarui Xu and Yen Wei
Journal of Materials Chemistry A 2012 - vol. 22(Issue 33) pp:
Publication Date(Web):
DOI:10.1039/C2JM32647G
Benzaldehyde, 4-(1,2,2-triphenylethenyl)-
Methanone, bis[4-(9H-carbazol-9-yl)phenyl]-
(4-CARBAZOL-9-YLPHENYL)-PHENYLMETHANONE
Benzene, 1,1'-(diphenylethenylidene)bis[4-nitro-
1,1',1'',1'''-ethane-1,1,2,2-tetrayltetrakis(4-methoxybenzene)
Benzene, 1,1',1'',1'''-(1,2-ethenediylidene)tetrakis[4-nitro-
Poly[(5,7-dihydro-1,3,5,7-tetraoxobenzo[1,2-c:4,5-c']dipyrrole-2,6(1H,3H)-diyl)-1,4-phenyleneoxy-1,4-phenylene]
Hydrazine,1,2-bis(4-nitrophenyl)-
Firebrake ZB 2335