new recent development and application of monolithic … · 2017. 4. 22. · more organic polymer...

58 B. Yu, H. Zhang, H. Cong, G. Chen, T. Xu and Y. Liu

© 2017 Advanced Study Center Co. Ltd.

Rev. Adv. Mater. Sci. 48 (2017) 58-67

Corresponding author: Hailin Cong, e-mail: [email protected]

RECENT DEVELOPMENT AND APPLICATION OFMONOLITHIC COLUMNS

Bing Yu, Hongbo Zhang, Hailin Cong, Guihuan Chen, Tao Xu and Yangchun Liu

Laboratory for New Fiber Materials and Modern Textile, Growing Base for State Key Laboratory, College ofMaterials Science and Engineering, Institute of Biomaterials and Engineering, Qingdao University, Qingdao

266071, China

Received: August 08, 2016

Abstract. Column is the most critical part of the chromatographic separation. Monolithic columnis a novel chromatographic column. The development of monolithic column significantly affectsthe development of chromatographic analysis. Monolithic column possesses high column effi-ciency and can reduce the analysis time as the permeability efficiency improves. Especially inprotein separation, the superior and unique porous structure of monolithic column could en-hance the permeability of proteins separation and improve separation efficiency. Recently, mono-lithic columns are developing rapidly due to their fascinating properties and enormous applica-tion. In this paper, recent development and application of monolithic columns are reviewed,which will deepen people’s understanding of this field and have profound implications for futuredesign of high-efficiency monolithic column.

1. INTRODUCTION

Chromatographic analysis is an important analyti-cal tool which has been used in many fields. In thechromatographic analysis system, column is themost critical separation part [1]. Traditional columnsare mostly packed columns which are packed byparticles. As a novel chromatographic column, themonolithic column was first prepared by S. Hjertenthrough the reaction of the acrylic acid and N,N-methylene-bis-acrylamide [2]. Monolithic column,which is prepared by organic or inorganic polymer-ization method in the column, possesses continu-ous stationary phase and superior porosity [3,4].As is shown in Figs. 1a and 1b, the selectivity ofthe packed column is enhanced by reducing par-ticles size, but the gap existing in the particles re-duces, which makes the permeability decrease andleads high back pressure that may negatively influ-ence on the operation of column. There is trade-off

between permeability and selectivity. The monolithiccolumn (Fig. 1c) possesses superior and uniqueporous structure which make it exhibit excellentselectivity with high permeability and fast analysistime [5,6]. Especially in protein separation, the struc-ture of the monolithic columns provides good flowchannel and enhances mass transport, thus signifi-cantly improves the chromatographic efficiency [7].Recent years, the monolithic columns have beenrapidly developed due to these advantages. Themonolith can be roughly divided into two categoriesaccording to different types of materials: 1. inorganicmonolith column; 2. organic monolith column [8].The development of the monolithic column plays avery crucial role in the development of chromatogra-phy studies. In the present review, recent develop-ment and application of the monolith column madeby different materials are summarized. This reviewwill broaden people’s understanding of this field and

mailto:[email protected]

59Recent development and application of monolithic columns

help to guide the future design of high-efficiencymonolithic column.

2. INORGANIC MONOLITHIC COLUMN

Inorganic monolithic column is primarily based onsilica materials. The main preparation methods in-clude sol gel, “one pot” and other polymerizationmethods. Among the reported synthetic ways, solgel is the conventional method. The process of thisreaction can be divided into two steps: hydrolysisand condensation. During the process, the Si(OR)

4

transforms into Si-O-Si and becomes oligomers andsilicon polymer. A continuous silicone bone and largepores form simultaneously. Tetramethoxysilane(TMOS) and ethylsilicate (TEOS) are common re-agents used to prepare the silica monolithic col-umn [9-12]. Inorganic monolithic column, with theadvantages of easy to synthesize, high mechanicalstrength and good thermal stability, has already beencommercialized by Merck KGaA, Darmstadt, Ger-many and other companies [13]. Recent years, inorder to improve the separation performance of inor-ganic monolithic column, and expand application ofinorganic monolithic column, many works have beendone. Zhenbin Zhang and his coworkers used the“one pot” method to prepare silica hybrid chiralmonolithic column which were modified by the wholephenyl isocyanate group beta cyclodextrin. Thismethod not only improved the introduction rate ofthe groups, but also obviously improved the perme-ability [14]. Chitosan with many significant biologi-cal and chemical properties were utilized to modifythe monolithic silica skeleton. The functionalizedmonolithic column showed good selectivity fornucleosides, nucleotides, aromatic acids and ali-

Fig. 1. Evolution of columns from (a) highly permeable and less-efficient packed columns to (b) less-permeable and highly efficient packed columns to ( c) highly permeable and highly efficient monolithiccolumns, reprinted with permission from F. Svec and C.G. Huber // Anal. Chem. 78 (2006) 2100, (c) 2006American Chemical Society.

phatic acids [15]. The high polarity of carboxylicacid was introduced into monolithic silica by an on-column polymerization acid on-column polymeriza-tion. The resulting monolithic column was success-fully used for hydrophilic interaction chromatogra-phy and showed more excellent performance com-pared with conventional particle-packed HILIC col-umns currently available [16]. Aldehyde groups wereintroduced into amino-functionalized silica monolithby reaction between amino groups and glutaralde-hyde. Liposome with primary amino groups wascovalent bound on the modified silica monolith. Dueto the presence of liposome, the prepared mono-lithic column was possible to be applied for the sepa-ration of structurally similar compounds [17]. Themonolithic silica column was also used for high chiralselector matrix. The polyproline-derived chiral se-lectors were bonded respectively to silica monolithto form the chiral stationary phases 1 (CSP-1) andthe chiral stationary phases 2 (CSP-2) monolithiccolumns (Fig. 2). Compared to analogous beadbased chiral stationary phases, the obtained col-umn showed higher enantioseparation and broaderapplication. Furthermore, the increase of the flowrate had little effect on separation performance [18].The metal nanoparticles were also used to enhancethe separation performance of silica-based mono-lith. The gold nanoparticles (GNPs) were introducedinto the thiol groups modified monolithic silica col-umn. Then Albumin from bovine serum (BSA) asthe chiral selector was used to modify the mono-lithic silica column taking advantage of goldnanoparticles with the large surface area and theability of conjugating with proteins. A number ofphenylthio-carbamyl amino acids (PTC-D/L-AAs)were separated via the BSA-GNPs-Silica monoliths


Fig. 2. Chemical structures of CSPs and their corresponding CSs, reprinted with permission from J. Lu, F.Ye, A. Zhang // J. Sep. Sci. 34 (2011) 2329, (c) 2011 Wiley online library.

[19]. The Ag nanoparticles were also successfullyused to modify hierarchically porous silica monolithwhich possessed amino groups because of themodification of (3- aminopropyl)triethoxysilane(APTES). And it was found that the retention forfour different compounds (benzene, naphthalene,anthracene and pyrene) improved (Fig. 3) and theresulting column possessed outstanding separationperformance of cis/trans-stilbene isomers [20].Polydopamine could provide p- p interaction, hydro-phobic properties, hydrogen bonding and ionic in-teraction due to the presence of many hydroxyl andamino groups besides benzene rings in structure ofpolydopamine. When silica monolithic column wasmodified by polydopamine via the self polymeriza-tion of dopamine, the obtained column was appli-cable to a variety chromatographic separation modes[21]. The block polymer Pluronic F127 was used asa dual-function template to prepare a hierarchicallyporous silica monolith with both macropores andmesopores. Then the resulting silica monolithiccolumn was modified by the C18 reagent. The ob-tained column shows good separation performancefor thiourea, toluene, ethylbenzen, propyl benzenebutylbenzene. And it also possesses a bimodalporous material with physical characteristics [22].Click chemistry has attracted much attention be-cause of simplicity, high efficiency, high selectivity

and high conversion. A novel glutathione (GSH)–silicahybrid monolithic column was prepared by a com-bination of thiol-ene click reaction and one-pot pro-cess. The obtained GSH–silica hybrid monolith wassuccessful used to separate small hydrocarbonsand biological molecules. And it was suitable for amixed-mode chromatography to test compoundsincluding hydrophobic, hydrophilic as well as cat-ion-exchange interaction [23]. The modified inorganicmonolithic column also has other advantages be-sides its built-in advantages. These advantages alsomake the modified silica monolithic column bewidely used in many areas such as micro- or nano-scale separation analysis, sample pretreatment andimmobilized enzyme reactor matrix.

3. ORGANIC MONOLITHIC COLUMN

The organic polymer monolith column can be pre-pared fast and the method is simple. It can be pre-pared in the glass tube, treated capillary or on themicrofluidic chip by the chain polymerization of poly-mer solution, which contains monomer, initiator,porogen and crosslinking agent. Then solvent suchas methanol is used to remove the column porogenand the residual soluble substances after the poly-merization. The ways of initiation include thermalinitiation, UV and so on. The surface and porosity


of the monolithic column can be controlled by chang-ing the reaction conditions and the composition ofpolymer solution [24-27]. As a stationary phase,organic polymer monolithic column is able to sepa-rate many substances such as proteins, peptides,nucleic acids and other cells. In addition, more andmore organic polymer monolithic columns have beencommercialized [28,29]. At present, according todifferent materials, organic polymer monolithic col-umns can be classified as polystyrene,polymethacrylate and polyacrylamide monolithiccolumns.

3.1. Polystyrene-based monolithiccolumns

Polystyrene-based monolithic column appearedearly and has developed for a long time. Its typesmainly contain poly (styrene-divinylbenzene) (PS-DVB) and the modified ones. The polystyrene-basedmonolithic column was first prepared by Svec andFréchet at the beginning of the 1990s. It has goodmechanical strength and remains excellent stabil-ity over a wide acidity (pH range 1–14). Based onnature hydrophobicity, the polystyrene monolithiccolumn can be directly some molecules [30]. Dueto modification of the benzene ring and copolymer-

ization with different substances, the polystyrene-based monolithic has made great progress and hasbeen widely used. Methacrylic acid was copolymer-ized with styrene and divinylbenzene, in which tolu-ene and isooctane were used as porogen, and AIBNwas used as initiator. It was found that column effi-ciencies of the obtained column could reach to about28,000 theoretical plates/m and the presence ofmethacrylic acid provided better separation perfor-mance for small organic molecules [31]. Anothernew type of monolithic column was synthesized byJiri Urban and his group. They used vinylbenzyl-ammonium chloride, styrene and divinylbenzene tocopolymerize, then hypercrosslinked to afford amonolith with an array of small pores. The surfacearea of column reached to 663 m2/g which wasmuch larger than that of the precursor column. Theobtained monolithic columns has been successfullyused in separation of small molecules and proteinsas well as size exclusion modes [32]. Octadecenewith C

18 long carbon chains were copolymerized with

styrene and divinylbenzene to prepare the PS-OD-DVB by one-step method. Compared to the PS-DVB column, C

18 long carbon chains inserted in the

PS-OD-DVB enhanced protein separation perfor-mance and the column exhibited higher loadingcapacity and higher resolution for the separation of

Fig. 3. Chromatograms of benzene (1), naphtha-lene (2), anthracene (3), and pyrene (4), using mono-lithic SiO

2 (A), SiO

2-NH

2 (B) and SiO

2-NH

2-Ag (C)

columns. Conditions: mobile phase 0.2% acetoni-trile/hexane, flow rate 1.0 mL/min, detector UV254nm, pressure 2.1 MPa , column length 83 mm, tem-perature 25 °C, reprinted with permission from Q.Zhou, P. Yang, X. Xiao // J. Sep. Sci. 36 (2013) 1516,(c) 2013 Wiley online library.

Fig. 4. Comparison of reverse-phase LC separationof polypeptides from human hemoglobin on the PS-DVB monolith and PS-OD-DVB monolith. Mobilephase: (A) 10% ACN, 0.1% (v/v) TFA in water; (B)60% ACN, 0.1% (v/v) TFA in water; gradient elutionprogram: 0–1–8min, 25–50–80% B; flow rate: 18.5mL /min; detection: UV 220 nm, reprinted with per-mission from C. Gu, L. Lin, X. Chen // J. Sep. Sci.30 (2007) 1005, (c) 2007 Wiley online library.


a and b chains of hemoglobin (Fig. 4) [33]. Micro-wave irradiation as novel polymerization method wasfirst used to prepare the monoliths of St–DVB–MAA.The reaction time was decreased from 24 h to 15min. The resulted column was evaluated by capil-lary electrochromatography (CEC), pressure-as-sisted CEC (pCEC) and low pressure-driven liquidchromatography and this polymerization method withshort reaction time had the potential to replace otherpolymerization methods [34]. The monolithic col-umn was made by copolymerization of vinyl ben-zene sulfonic acid, styrene and DVB. It is reportedthat the column with high separation resolution andhigh separation efficiency has been successfullyused in the separation of acidic substances [35].The preparation of micro- and nano-porous polymernetworks could be formed through Friedele Craftsreaction. Based-on poly(styrene-divinylbenzene)monoliths, external crosslinkers were used to pre-pare hypercrosslinked poly(styrene-divinylbenzene)monoliths by Friedele Crafts reaction. Surface ar-eas of the hypercrosslinked column large increasedto 900 m2/g and the column efficiencies for retainedanalytes were more than 70,000 plates/m [36].Graphene oxide (GO), as commonly functionalizedgraphene-based materials, possesses many aro-matic rings and rich oxygen functional groups in-cluding epoxy, hydroxyl and carboxyl. A novel pAS-GO@PS-DVB monolithic column was synthesizedby copolymerization of styrene (St) and divinyl-ben-zene (DVB) and Vinyl functionalized GO. The pro-posed column exhibited superior performance thanadsorbed GO-based monolith and gave effectiveseparation for neutral and polar compounds [37].The rapid development of modification, preparationmethods as well as inorganic materials will makepolystyrene-based monolithic column become in-creasingly diverse and promote the column to adaptto the wider application.

3.2. Polymethacrylate-basedmonolithic columns

Polymethylacrylate is one of the most commonpolymer materials used in monolithic column. Thiskind of monolithic column was prepared by usingmethacrylic acid or its derivatives as the monomer,ethylene glycol dimethacrylate (EDMA) or othersas the cross-linking agent, and then the monomerand cross-linking agent are mixed with the porogenicagent and initiator. The porogenic agent occupiesspace instead of participating in the polymerization.After polymerization, unreacted monomer andporogen is washed out to fabricate porous struc-

ture. Butylmethacrylate (BMA) and glycidyl meth-acrylate (GMA) are the most commonly used mono-mers. The BMA exhibit hydrophobicity due to alkylgroups instead of ester. So monolithic column syn-thesized by BMA can be used to separate proteinor benzene homologues [38]. Epoxy group with highreactivity presented in GMA structure can providevarious modification methods [39]. It is just for thisreason that PGMA-based monolithic columns de-velop rapidly and are widely applied. It was reportedthat methacrylic acid (MAA) copolymerized withGMA and EDMA. The copolymer was modified withethylenediamine. The finally obtained column withamino and carboxyl groups could be used as a weakion exchange monolithic column. This column wasapplicable to serve as on-line cleanup material forsimultaneous determination of oxacillin and clox-acillin in human urine and plasma [40]. Native andderivative b-cyclodextrins (b-CDs) are doughnutshaped cyclic oligosaccharides and frequently usedto be chiral selectors. A novel b-cyclodextrin deriva-tive bearing 4-dimethylamino-1,8-naphthalimidefunctionalities was introduced into Poly(GMA-EDMA) monolith as shown in the Fig. 5. Acidic enan-tiomers (ibuprofen and naproxen) were successfullyseparated by the modified column [41]. Ionic liq-uids composed of cations and anions own high ther-mal stabilities and negligible vapor pressures. Aftermodification of poly(GMA-MAA-EGDMA) by ionicliquids, the resulting column possessed high sen-sitivity as well as precision and recovery. And it ex-hibited excellent separation performance for theo-phylline and caffeine [42]. Vinylphenylboronic acid(VPBA) exhibited hydrophobic and hydrophilic/ion-izable because of the existence of benzene ring andboronic acid group in the structure of VPBA. Themonolithic column synthesized by VPBA, GMA, andEDMA possessed hydrophobic, hydrophilic, as wellas cation-exchange interaction in the same chro-matographic conditions and behaved good separa-tion performance in acid and alkaline substances[43]. Single stranded DNA or RNA oligonucleotidesas aptamers can be screened from a large randomcombinatorial nucleic acid library. Anti-lysozymeDNA was introduced into poly(GMA-EDMA) mono-lith to form immobilized anti-lysozyme DNA aptamerand the column could selectively extract and screenlysozyme (Lys) with a high precision and reproduc-ibility [44]. Thiol groups were introduced intopoly(GMA-EDMA) monolith and b-CDs respectively.Based-on the interaction between thiol groups andgold nanoparticles, poly(GMA-EDMA) monolith wassuccessfully modified by b-CDs. It was found thatthree pairs of drug enantiomers (chlorpheniramine,


zopiclone and tropicamide) were successfully sepa-rated through the resulting monolithic column [45].Carbon nanotubes with large surface-to-volume ra-tio were incorporated in the poly(GMA-EDMA) col-umn. The separation performance for small mol-ecules in the reversed phase was enhanced [46].Metal-organic frameworks (MOFs) as an emergingclass of highly porous materials possessed largesurface areas, highly uniform pores. The HKUST-1monolithic columns prepared by polymerizationmixture containing GMA, EDMA, MOFs HKUST-1,dodecanol, cyclohexanol, and AIBN (Fig. 6). Theprepared HKUST-1 monolithic columns possessedmultiple interaction such as hydrophobic effect and- electrostatic stacking property [47]. ATP, ADP,

Fig. 5. The structures of DMAN--CD (A) and ibuprofen and naproxen (B) and reaction scheme for thesynthesis of poly(GMA-co-EDMA) monolith and post-modification with DMAN--CD (C), reprinted with per-mission from Y. Tian, C. Zhong, E. Fu // J. Chromatogr. A. 1216 (2009) 1000, (c) 2009 Elsevier.

and AMP were hardly directly determined becauseof their similar structure. N-methylol acrylamide(NMA) as functional monomer was copolymerizedwith GMA and EDMA. The obtained monolithic col-umn had a very good separation performance forATP, ADP and AMP due to enhancement of the hy-drophilicity. Furthermore, the column is possible tobe used in separating other biological molecules inthe future [48]. PEG as hydrophilic macromoleculewas attached into the GMA monolithic column withtosylation PEG. Due to the presence of PEG groups,the monolithic column exhibited increased theoreti-cal plate efficiency and it could separate eluentswith different polarities [49]. Diaethylamine and tri-ethylamine were used to modify GMA monolithic


column. It was found that the monolithic columnmodified with triethylamine performed better on pu-rification of plasmid measles vaccine than that ofmodified with diaethylamine by anion exchangechromatography. Compared with the diaethylaminefunctionalized monolith, plasmid based vaccinecould be better purified by the monolithic columnmodified with triethylamine in a low NaCl contentand neutral environment [50]. Vinyl groups werelinked with Fe

3O

4 nanoparticles by silanization. The

Fe3O

4 nanoparticles were incorporated by copoly-

merizing with GMA and EDMA at UV irradiation.The introduction of Fe

3O

4 nanoparticles increased

the surface area of the monolith, making the ob-tained column show increased retention and highcolumn efficiency for alkyl benzenes andorganophosphorous pesticides [51]. The interactionbetween the gold nanoparticles and the thiol groupwas also utilized to attach 1-octanethiol and 1-octadecanethiol to thiol group functionalized poly(GMA-EGDMA) monolith. The gold nano-particleswere introduced into the monolith to enhance thecoverage of monolith surface. The resulting mono-lithic columns successfully separated proteins inreversed phase mode [52]. As classical sulfonamide

Fig. 6. Synthesis processes of HKUST-1-poly(GMA-EDMA) monolith, reprinted with permission fromS. Yang, F. Ye, Q. Lv // J. Chromatogr. A. 1360 (2014) 143, (c) 2014 Elsevier.

drugs, Sulfamethoxazole (SMX) and sulfanilamide(SAA) have been utilized to prepare poly(GMA-SAA-co-EDMA) and poly(GMA-SMX-co-EDMA) column(Fig. 7). In particular, the poly(GMA-SMX-co-EDMA)exhibited a selective affinity to trypsin besides goodseparation performance for small molecules [53].GMA with highly reactive epoxy groups makespolymethacrylate-based monolithic column possessmore possibility of modification. The different modi-fication methods promote this class monolithic col-umn to be applied in more areas.

3.3. Polyacrylamide-based monolithiccolumn

Polyacrylamide is an important material of electro-phoresis biological separation and identification ofthe biological molecules. Normally, acrylamide, N-isopropyl acrylamide, methylacrylamide, N-allyldi-methylamine are used as monomer and N,N’-methylenebisacrylamide is used as crosslinkedagent. The preparation system is a typical aqueouspolymerization system and the product possessesgood biocompatibility. The polyacrylamide-basedmonolithic column is suitable for separation of bio-


Fig. 7. Scheme for the preparation of the poly(GMA-SA-co-EDMA) monolithic columns, reprinted withpermission from Y. Xiao, J. Guo, D. Ran // J. Chromatogr. A. 1400 (2015) 47, (c) 2015 Elsevier.

logical macromolecules. But mechanical propertiesof the column are poor [54,55]. In recent years, manyresearchers applied many different polymerizationor modification methods to improve separation per-formance of polyacrylamide monolithic. Organotel-lurium-mediated living radical polymerization (TERP)as a general living radical reaction was applicableto many different types of monomers. The polyacry-lamide monoliths synthesized by TERP not onlykept the characteristics of the polyacrylamide mono-lithic column, but also had well-defined macroporeswith narrow pore size distributions and it can en-dure the surface tension arising in the repetitiveswelling and drying (Fig. 8) [56]. Steric exclusion

chromatography (SXC) as a new mode of proteinchromatography required the column with hydrophilicstationary phase surface. Polyacrylamide-basedmonolith prepared by Chuan Wang et.al was suit-able candidate for this mode because the abundanceof hydrophilic amino groups and its porous struc-ture with 10–100 mm macropores ensured SXC tooperat at low back pressure [57]. Doxorubicin asanticancer drug covalently bonded to the polyacry-lamide through the glutaraldehyde method. The poly-acrylamide monolithic column provided macroporousmatrix that made it possible to screen against ph-age-displayed human liver cDNA library with a highspeed and little nonspecific adsorption of phages

Fig. 8. Synthesis processes of polyacrylamide monolith, reprinted with permission from J. Hasegawa,K. Kanamori, K. Nakanishi // Macromol. Rapid. Commun. 30 (2009) 986, (c) 2009 Wiley online library.


Fig. 9. Schematic diagrams for preparing the amide functionalized hydrophilic monolithic capillary column.,reprinted with permission from H. Jiang, H. Yuan, Y. Qu // Talanta 146 (2016) 225, (c) 2016 Elsevier.

[58]. The novel monolith was prepared by copoly-merization of N-vinyl-2-pyrrolidinone (NVP),acrylamide (AM), and N,N’-methylenebisacrylamide(MBA) in a UV transparent capillary by the in situphoto-polymerization (Fig. 9). The obtained columnwas applied in hydrophilic interaction chromatogra-phy (HILIC). This polymerization method is fast andconvenient. The resulting column exhibited highperformance for the separation of glycopeptides [59].The polyacrylamide-based monolithic column con-sisted of highly biocompatible materials is excel-lent support for separation of biomolecules. Thisrequires more research to discover applications ofpolyacrylamide-based monolithic column.

4. CONCLUDING REMARKS

Monolithic column with unique crosslinked porousstructure possesses higher separation performancewith high efficiency than the traditional particles-packed columns. In addition, it also has good re-peatability and very strong stability. Recent years,capillary columns have also been greatly developedand it can be used to successfully separate largemolecule as well as small molecules under smallvelocity and injection volume. Up to now, extensiveresearches have greatly improved the separationperformance and strongly promoted the applicationof monolithic column through modification and newsynthetic methods. At present, some monolithiccolumns have been commercialized and the mono-lithic columns have been used in many fields. But itis not enough to deal with separate demand con-stantly emerging in the development of other disci-plines such as screen of peptides in life science,separation of different generation novel dendrimersin materials science as well as chiral separation in

chemistry science. Therefore, the novel materials,preparation method, modification method promotethe development of monolithic column to solve theseproblems.

ACKNOWLEDGEMENTS

This work is financially supported by the NationalNatural Science Foundation of China (21375069,21404065, 21675091, 21574072), the Natural Sci-ence Foundation for Distinguished Young Scientistsof Shandong Province (JQ201403), the Project ofShandong Province Higher Educational Science andTechnology Program (J15LC20), the Graduate Edu-cation Innovation Project of Shandong Province(SDYY14028), the Scientific Research Foundationfor the Returned Overseas Chinese Scholars of StateEducation Ministry (20111568), the Key Researchand Development Project of Shandong Province(2016GGX102028, 2016GGX102039), the People'sLivelihood Science and Technology Project ofQingdao (166257nsh),and the Postdoctoral Scien-tific Research Foundation of Qingdao.

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