The Preparation of Carbon Based Nano Materials with Multifunction and Their Applications in Biomedical Field

Author:Zhang Zuo

Supervisor:fan jun


Degree Year:2019





Nowdays carbon nano materials are beening developed and applied widely.Graphene oxide(GO)and carbon quantum dots(CDs)are 2D and 0D carbon nano materials respectively,and due to their excellent biosecurity and hydrophily,they are being employed in biomedical field.Although some anticancerogen have been used to carbon nano drug delivery system,and anti-inflammatory drugs have important roles in treating some diseases,but there have few researches on combining carbon nano materials with anti-inflammatory drugs;besides,some novel complexes composed of either antibacterial functional metals or their oxides with carbon nano materials begin to be payed attentions in this field.Antibiotics have prominent curative effects on some diseases,however the hazards resulting from their overuse are not to be ignored.CDs with good photoluminescence property were applied to sense ions and molecules,and some progress have been made,but however it will be significant that the residual antibiotics in water environment are sensed by CDs.Thus in this dissertation,GO,GO loading metronidazole(GO-MTR)and nano ZnO(GO-ZnO),CDs with doped nitrogen(N-CDs)and doped boron(B-CQDs)as multi-functional carbon nano materials were prepared separately and characterized with SEM,TEM,XRD,XPS,N2 adsorption-desorption,Raman scattering spectroscopy,FTIR and UV-vis analytic technique,respectively.Furthermore they were applied to load anti-inflammatory drugs and antineoplasties drugs,inhibit bacterials and sense antibiotics in water environment.The main contents and research results are as follows.GO and CDs were reviewed firstly,and then their biomedical applications were summarized,all which would be the theories foundation of this dissertation.In view of few researches on GO loading anti-inflammatory drugs,different preparations of GO-ZnO nano complex and their applications to inhibiting bacterials,as well as antineoplastic drugs deliveried and antibiotics detected by doped CDs,so it would be probability,and all were the guidance of this dissertation.Both H2SO4 and H2SO4-H3PO4 mixed acid system were used to prepare GO respectively,then MTR were loaded on them to be produced GO-MTR drug loading system.It showed GO prepared by mixed acid had better structure,such as paper-thin surface,0.800 nm of lattice spacing and crystal face with graphene(001),and linked groups such as carboxyl,hydroxyl,epoxy,carbonyl and so on;the specific surface area of GO was to 541.8 m2·g-1 and the disorder degree of carbon atoms in GO was increased.The study on GO loading MTR indicated that alkaline solution,raising temperature and increasing the initial concentration of MTR would be contributed to prepare GO-MTR;the adsorption amount and loading percentage of MTR were 494 mg·g-1 and 98.8%respectively on suitable conditions.GO loading MTR were close to the quasi-second-order kinetics and Langmuir isotherm respectively,and the interaction patterns between GO and MTR might beπ-πstacking,hydrogen bond and electrostatic interaction.The release of MTR from the loading drug system in vitro were dependent on pH value of the medium,and the acidic condition was in favor of MTR release.GO-ZnO nano complexes were prepared with three methods and their antibacterial properties on Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus)were evaluated.The results showed GO-ZnO prepared with one step reflux method were preferable,and ZnO with less then 200 nm of spherical particles formed from hexagonal wurtzite structure with crystal size of about 20 nm were dispersed well on GO.The complexes had greater specific surface area than separate ZnO.About 99.9%of E.coli were inhibited by GO-ZnO in 0.5 h,but 90%of S.aureus were depressed with the same amount of the complexes in 4 h.The GO-ZnO nano complexes could exert more antibacterial performance via synergistic effect.N-CDs were prepared by using one-step hydrothermal synthesis with glycine as the precursor and polyethylene glycol 2000 as the modifier,and they were applied to load doxorubicin(DOX).The results indicated that N-CDs were quasi spherical particles with 521 nm diameter,and had 442 nm of maximal emission wavelength with bright blue fluorescent when they were excited at 366 nm;besides they were good water solubility,favorable stability and high quantum yield with 30%.The drug loading capacity was 24.25 mg·g-1 and the encapsulation efficiency was 77.23%at pH 9.00 with 36 h of dialysis.DOX were loaded on N-CDs via hydrogen bond,electrostatic interaction andπ-πstacking.A slightly acid medium could facilitate DOX release from drug loading system,and the cumulative release percentange of N-CDs-DOX in PBS with a pH value of 5.50 could reach up to 76.67%in 23 h.B-CQDs as fluorescence probe were prepared by using one-step hydrothermal synthesis with citric acid as carbon source and H3BO3 as boron source,applied to detect amoxicillin(AMX)residual in water environment.The results showed B-CQDs with 5:1 of atom mole ratio for carbon versus boron and pH at about 3 could be acquired when citric acid and boric acid reacted on suitable conditions.B-CQDs with graphite phase stucture had less than 5 nm of particle size and 30.85%of quantum yield.The fluorescence signal of the sense system composed of B-CQDs-AMX was influenced by the initial concentration of AMX,pH value of B-CQDs and mixture temperature.The fluorescence intensity of the detection system increased linearly with increasing the concentration of AMX when the antibiotic was in the range of 1.43429.12μmol/L,and the limit of detection was 0.82μmol·L-1.The mechanism of detection might be that B-CQDs combine with AMX via hydrogen bond and probable electrostatic interaction,and their combining preference could be enhanced with increasing temperature of detection system in the range of 288313 K.This dissertation may be research foundations for multi carbon nano materials applied in the biomedical field.