Study on the Determination of Chitosan by Using Alizarin Red as An Electrochemical Activity Probe

建立了以茜素红(AR)为电活性探针间接测定无电活性壳聚糖(CS)的新方法。研究了AR及其与CS的结合物AR-CS于0.1 mol/L HAc-NaAc(pH 4.5)缓冲溶液中在玻碳电极(GCE)上的电化学行为。AR与CS-AR在GCE上均能形成一准可逆的吸附伏安峰(Vpc=-0.46 V,Vpa=-0.41 V,ΔVp=0.05 V)。测定了X、α、Ks等电化学参数。实验表明,CS在低浓度(1.25×10-8~2.5×10-7mol/L)和高浓度(2.5×10-7~1.25×10-5mol/L)的条件下对体系的峰电流分别具有线性增敏和减敏效应。采用标准加入法测定了不同样品中壳聚糖的含量,其回收率在97%~102%之间,结果满意。 A new method to determine chitosan （CS） indirectly was established by using alizarin red （AR） as an electrochemical activity probe. The electrochemical behaviour of the interaction between AR and CS was investigated in 0. 1 mol/L HAc - NaAc buffer solution（pH 4.5） on the glassy carbon electrode（GCE） by voltammetry. The results show that AR and AR - CS complex can be easily reduced or oxidized on the GCE and they have a pair of well-defined quasi-reversible waves （ Vpc = -0.45 V, Vpa =-0.41V, △ Vp =0. 04 V） with adsorption characteristics. The electrochemical parameters such as proton numbers （X）, electron transfer coefficient（α）, reaction rate constant（K） were measured by cyclic voltammetry. The increase and decrease of reductive peak currents of AR are proportional to CS concentration in the range of 1.25 × 10^-8 - 2.5 × 10^- 7 mol/L and 2.5 ×10^-7- 1.25×10^-5 mol/L, respectively. The method has been successfully used for the determination of CS in different samples by standard addition. The recovery was measured to be 97% - 102%.国家自然科学基金资助项目(20475068);广西壮族自治区自然科学基金资助项目(0141037,0342018

Determination of Nitrofurantoin and Its Electrochemical Behavior at Cobalt Ion Implantation Modified Glassy Carbon Electrode

呋喃妥因 (NFT)在 0 .1mol/LHAc NaAc (pH 4 .0 )溶液中于钴 /玻碳 (Co/GC)离子注入修饰电极上产生一灵敏的伏安还原峰 ,峰电位为 - 0 .2 6V(vs.Ag/AgCl) ,峰电流与NFT浓度在 6 .0× 10 -8～ 5 .0× 10 -6mol/L范围内呈线性关系 (r =0 .9987) ,检出限为 1.0× 10 -8mol/L。用线性扫描伏安法和循环伏安法研究了NFT的伏安行为、吸附特性和电极反应机理。测定了电子转移数 (n =4 )、转移系数 (α =0 .5 8)和参与反应的质子数 (X =4 )等电化学参数。结果表明该电极过程为一具有吸附性的不可逆过程。该法用于片剂中NFT含量的测定 ,得到满意的结果。用标准加入法测得该法的回收率为 94 .0 %～ 98.5 %。In 0.1 mol/L HAc-NaAc buffer (pH 4.0) solution, a sensitive reductive peak of nitrofurantion was obtained by linear sweep voltammetry on the cobalt/glassy carbon (Co/GC) ion implantation modified electrode. The peak potential was -0.26 V ( vs. Ag/AgCl). The linear range between the peak current and the concentration of nitrofurantoin was 6.0 x 10(-8) similar to5.0 x 10(-6) mol/L (r = 0.9987). The detection limit was 1.0 x 10(-8) mol/L. The voltammetric behaviour, adsorptive characteristic and the electrode reaction mechanism of nitrofarantoin were studied by means of linear sweep and cyclic voltammetry. Some electrochemical parameters such as electron transfer numbers (n = 4), electron transfer coefficient (alpha = 0.58) and proton numbers (X = 4) have been determined. The electrode reduction process of nitrofurantoin at Co/GC was irreversible with adsorptive characteristic. This method has been used to determine the content of nitrofurantoin in medical tablets. The recovery was determined to be 94.0% similar to 98.5% by means of standard addition method.广东省自然科学基金 (No .0 1110 5 ,0 3 15 77);广西壮族自治区自然科学基金 (No .0 14 10 3 7,0 3 42 0 18);广西民族学院引进人才启动基金 (No .OHHX0 0 0 0 2 )资助项

Amperomertric Glucose Biosensor Based on Sol-gel Chitosan /Sil ica HybridMaterial

近年来，基于溶胶-凝胶技术的有机/无机杂化复合材料由于具有有机物的柔性和易修饰性，以及无机物的刚性和稳定性等，因此有利于保持生物分子的活性和生物传感器的研制．壳聚糖(CS)具有易成膜性和生物相容性，其在生物传感器中的研究已受到重视．本文通过原位溶胶-凝胶(Sol-gel)技术，Abstract　A new type of so l-gel /o rg anic hybrid composi te film based o n chi tosan ( CS ) w ith methy trimetho xy silane ( M TOS ) was dev eloped fo r the fabricatio n of an amperomet ric g lucose biosenso r. The hybrid composi te fi lm w as used to immo bilize gluco se oxidase( GOD) o n the surface of Prussian Blue( PB) -modi fied g lass carbo n electrode. Effect s of some ex perimental conditions such as pH, tempera ture a nd applied potential etc. on the current response of the bio sensor w ere investiga ted. The bio sensor has a fast respo nse less than 10 s a nd linear calibratio n ra ng e from 5. 0× 10- 6 to 2. 4× 10- 3 mo l /L w ith detection limi t of 1. 0× 10- 6 mo l /L. The apparent Michaelis-Menten constant Km is found to be 3. 2× 10- 3 mol /L. The activa tion energy fo r enzymatic reactio n is calculated to be 21. 9 k J /mol. The bio sensor has a high sensitivi ty ( 420 μA· mol- 1 · L) , long-term stabi li ty and g ood selectivi ty. This method has been used to determine the co ntent of g lucose in the rea l blood samples.广东省自然科学基金 (批准号 :0 1110 5,0 3 15 77);广西壮族自治区自然科学基金 (批准号 :0 14 10 3 7,0 3 42 0 18)资

An amperometric hydrogen peroxide biosensor based on chitosan/silica sol-gel composite films incorporating horseradish peroxidase

利用溶胶 凝胶法制备壳聚糖 二氧化硅有机无机复合杂化膜,用于对辣根过氧化酶进行固定,制得测定H2O2的电流型生物传感器。以1mmol/LK4Fe(CN)6作为电子媒介体。研究了各种因素如壳聚糖与二氧化硅的比率、pH、温度、工作电位等对传感器响应电流的影响。计时电流法测定H2O2的线性范围为2.0×10-6～6.8×10-4mol/L,检出限为8.0×10-7mol/L。测得酶催化动力学参数米氏常数Km=0 87mmol/L。用该法对实际样品进行了测定。Abstract :A new type of chitosan/silica sol-gel organicinorganic hybrid composite film was developed for the fabrication of an amperometric hydrogen peroxide(H2O2) biosensor.The composite film was used to immobilize horseradish peroxidase(HRP)on a gold disk electrode . Hexacyanoferrate (K4Fe(CN)6)was added to the solution as an electron mediator .Effects of some experimental conditions such as the ratio of chitosan to silica , pH , temperature and applied potential on the response current of the biosensor were investigated .The biosensor had a fast response of less than 10 s and linear calibration range of 2 .0 ×10 -6 ～ 6 .8 ×10 -4 mol/L with detection limit of 8 .0 ×10 -7 mol/L for H2O2 .The Michaelis-Menten constant Km was found to be 0.87 mmol/L .This method was used to determine the content of H2O2 in the real sample .广东省(011105,031577);广西壮族自治区(0141037,0342018);自然科学基金;广西民族学院引进人才启动基金(OHHX00002)资助项

Electrochemical Behaviour of the Interaction Between Chitosan and Al izarin

Abstract　The interaction betw een Ali zarin red ( AR) and Chi tosan ( CS) w as inv estigated in 0. 1 mol /L HAc-NaAc buf fer solution ( pH= 4. 5) on the glassy carbo n elect rode ( GC) by cyclic and square wave voltammet ry. The results show that bo th AR and AR-CS complex have a well-defined quasi-rev ersible redox wave( Vpc= - 0. 46 V , Vpa= - 0. 41 V ) with adsorption characteristics. Electron t ransfer coefficient (T) and reaction rate constant (Ks ) of AR and AR-CS were measured by cyclic voltammet ry. The maximum binding numbers m betw een AR and CS was found to be 2 500. The ex periment results confirmed that low er concentratio n of CS can enhance the detection sensitivity , w hile hig her concent ration of CS can low er the detection sensitivi ty. In the presence of 2. 0× 10- 5 mol /L AR, the peak current of sy stem are proportional to CS concentration in the rang e of 1. 25× 10- 8～ 2. 5× 10- 7 mol /L, and inv ersely proportional to CS concentration in the rang e of 2. 5× 10- 7～ 1. 25× 10- 5 mol /L, respectiv ely. The binding interaction mechanism w as also discussed.国家自然科学基金(批准号:20475068);广西壮族自治区自然科学基金(批准号:0141037,0342018)资

Non- labeled HBsAg Immunosensor Based on Bilayer Lipid Membrane

采用固体铂盘电极支撑的双层类脂膜(Pt-BLM)技术固定乙肝表面抗体(HBsAb),研制成Pt-BLM-HBsAb电位型非标记免疫传感器,用于检测人血清中乙肝表面抗原(HBsAg)。对影响构筑BLM的各种因素进行了研究,用循环伏安法对Pt-BLM进行了表征。传感器对HBsAg呈Nernst响应,其线性范围为2~320μg/L,线性回归方程为ΔV=-1.09+32.4 lgρ(HBsAg),线性相关系数r=0.999 8。该传感器响应迅速,灵敏度高,稳定性及选择性好,于4℃干态保存4周,其响应信号基本不变。将其用于临床血清检验,结果满意。 A new type of non-labeled potentiometric immunosensor（Pt - BLM - HBsAb） for the determination of hepatitis B surface antigen （HBsAg） was developed by immobilizing hepatitis B surface antibody （HBsAb） in the bilayer lipid membrane（BLM）, which was supported hy the platinum disk electrode（Pt- BLM）. Effects of some experimental conditions such as the ratio of cholesterol and lecithin, species of the solvent, and the added quantum of HBsAb etc. on the potential response of the immurnosensor were investigated. The immunosensor was characterized by cyclic vohammetry. The response potential of the inununosensor is linear with p （HBsAg）, over a concentration range of 2- 320μg/L with a correlation coefficient of 0. 999 8 and a linear regression equation of ΔV = - 1.09 ＋ 32.4 lgρ（HBsAg） . The immunosensor has a fast response time, high sensitivity, good selectivity and stability of about four weeks when storing a dry, state at 4℃. This method has been used to detennine the real serum samples with satisfactory results.国家自然科学基金资助项目(20475068);广东省自然科学基金资助项目(031577);广西壮族自治区自然科学基金资助项目(0342018

Preparation and Characterization of Chitosan/Silica Hybrid Film Immobilizing Horseradish Peroxidase

利用生物相容性良好的天然高分子聚合物壳聚糖(CS)与四乙氧基硅烷(TEOS)通过原位溶胶-凝胶法制备壳聚糖／二氧化硅有机无机杂化复合膜,用杂化膜对辣根过氧化酶进行固定,用红外光谱法、扫描电镜法对膜进行了表征。以金电极和固定化酶膜构建过氧化氢生物传感器,并用循环伏安法和计时电流法对传感器的特性进行了研究。结果表明,用于研制固定化酶生物传感器时,杂化膜不仅对底物的响应时间快(小于10s),而且能较好地保持酶的催化活性。求得酶促催化反应的表观米氏常数为0.87mmol／L。Abstract :A new type of organic -inorganic hybrid film was prepared by in_si tu sol -gel with natural polymer chitosan(CS)with good biocompatibili ty and tetraethyl orthosilicate(TEOS), and characterized by fourier transform infrared spectroscopy(FT-IR)and scanning electron microscope(SEM).The hybrid film was used to immobilize horseradish peroxidase(HRP)on the surface of a gold electrode to construct a hydrogen peroxide biosensor whose performance was investigated by cyclic voltammetry and chronoamperometry .The results show that the biosensor fabricated with hybrid film has a fast response time for substrate(less than 10 s)and a good ability retaining the activity of enzymes .The apparent Michaelis-Menten constant was found to be 0.87mmol/L.广东省自然科学基金资助项目(011105;031577);广西壮族自治区自然科学基金资助项目(0141037;0342018);湖南大学化学生物传感与计量学国家重点实验室开放基金资助项目(2003