CN104764763A - Method for determination of gelation time by low field nuclear magnetic resonance technology - Google Patents

Method for determination of gelation time by low field nuclear magnetic resonance technology Download PDF

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CN104764763A
CN104764763A CN 201510097111 CN201510097111A CN104764763A CN 104764763 A CN104764763 A CN 104764763A CN 201510097111 CN201510097111 CN 201510097111 CN 201510097111 A CN201510097111 A CN 201510097111A CN 104764763 A CN104764763 A CN 104764763A
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time
curve
t2
method
hydrogel
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CN104764763B (en )
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李秀男
李亚琼
陈超
赵大伟
苏志国
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中国科学院过程工程研究所
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Abstract

The invention discloses a method for determination of gelation time by a low field nuclear magnetic resonance technology. The method comprises the steps of: employing a Carr-Purcell-Meiboom-Gill (CPMG) sequence to determine a nuclear magnetic resonance decay curve of hydrogel heated for different time at a specific temperature, and conducting fitting by a multi-exponent equation to obtain a T2 distribution curve; calculating the weighted average values of gel internal water corresponded T2 distribution peaks at each time point, and drawing a curve of the T2 value changing along with time; and using a bilinear regression model to fit the T2-t curve, determining the solution-gel transition point of the system, and acquiring the gelation time. The invention provides a new method for simple, rapid and nondestructive determination of gelation time.

Description

一种应用低场核磁共振技术测定凝胶化时间的方法 A method of application of low-field NMR Determination of the gelation time

技术领域 FIELD

[0001] 本发明属于高分子材料技术领域,具体涉及一种应用低场核磁共振弛豫技术测定温敏水凝胶凝胶化时间的方法。 [0001] The present invention belongs to the technical field of polymer materials, particularly low-field NMR relaxation art methods thermosensitive hydrogel gelling time relates to the determination of an application.

背景技术 Background technique

[0002] 温度敏感型水凝胶具有能够在环境温度刺激下发生溶液-凝胶转换的特性,这种环境响应性使其在生物医药,生物技术等领域具有很好的应用前景,尤其适合作为可注射的原位水凝胶药物释放载体。 Gel transition characteristic, the responsiveness of such an environment to have a good prospect in the field of biomedicine, biotechnology, particularly suitable as - [0002] temperature-sensitive hydrogel capable solution occurs at ambient temperature for stimulation situ hydrogel release injectable pharmaceutical carrier. 温敏水凝胶的凝胶化温度和胶凝时间是决定其能否成为合适的体温敏感型水凝胶的关键性因素,因此温敏水凝胶凝胶化特性的表征对于其应用十分重要。 Temperature sensitive gelling temperature of the hydrogel and to determine their gelation time can become a suitable temperature sensitive hydrogel key factor, so Hydrogels temperature sensitive gelling properties for its application is very important.

[0003] 温敏水凝胶体系在室温下粘度较低,能够保持较好的流动状态,当环境温度上升到体温时,聚合物链之间的疏水作用增强,溶液的粘度剧烈增加,聚合物链的聚集使整个体系固化成为凝胶。 [0003] temperature sensitive hydrogel systems lower viscosity at room temperature, can maintain a good fluidized state, when the ambient temperature rises to body temperature, the hydrophobic interaction between the polymer chain enhancer, drastically increases the viscosity of the solution, the polymer chains aggregation system so that the whole cured into a gel. 这种温敏型体系已被广泛用于多种蛋白、多肽和小分子药物的控制释放, 并且表现出了较好的持续释放效果。 Such temperature-sensitive system has been widely used in a variety of proteins, peptides and small molecules controlled release of drugs, and exhibits good sustained release effect. 常用来表征温敏水凝胶凝胶化时间的方法有反转试管法,差示扫描量热法(DSC)和流变学方法。 Used to characterize the thermosensitive hydrogel gelling time inversion methods are the tube method, differential scanning calorimetry (DSC) and rheology. 但这些方法都存在一些缺点,如反转试管法的结果容易受主观影响,DSC法不适用于凝胶化过程中热效应较弱的凝胶,而流变法中由粘性模量和弹性模量相等而得到的胶凝点可能是频率依赖性的,会出现一些错误。 However, these methods have several disadvantages, such as the results of inversion tube method is easily influenced by subjectivity, a DSC method is not suitable for the process of gelling the gel weaker thermal effect, and a rheological method is equal to the viscous modulus and the elastic modulus the resulting gel point may be frequency dependent, there will be some errors.

[0004] 水凝胶中含有大量的水分,并且在由溶液向凝胶转变的过程中,溶液粘度的变化、 聚合物链的聚集和凝胶三维网络的行成都涉及到体系中水分子活动性的变化,因此可以通过水分子活动性的变化来对凝胶化过程进行表征。 [0004] The hydrogel contains a large amount of water, and during the transition to the gel from the solution, change in solution viscosity, the line aggregation and gel polymer chains three-dimensional network system involves Chengdu mobility of water molecules It changes, so can be characterized by a change in the process of gelation activity of the water molecules. 低场核磁共振法由于工作频率低,不能区分不同质子的化学位移,但是可以通过弛豫时间来反映样本的特征,可以通过水分子的活动来揭示内部的变化。 Low field NMR method due to the low operating frequency, can not distinguish between different chemical shifts of protons, but may be reflected by the characteristic relaxation time of the sample can be revealed by changes in the internal activity of the water molecules. 所以,可以将低场核磁共振技术引入温敏水凝胶凝胶化过程的表征,建立一种新的表征方法。 Therefore, low-field nuclear magnetic resonance techniques may be introduced to characterize thermosensitive hydrogel of the gelation process, to establish a new characterization.

发明内容 SUMMARY

[0005] 本发明的目的在于提供一种新的应用低场核磁共振技术测定温敏水凝胶凝胶化时间的方法。 [0005] The object of the present invention to provide a novel method of application of low-field NMR techniques thermosensitive hydrogel of the gel time was measured.

[0006] 本发明提出的应用低场核磁共振技术测定温敏水凝胶凝胶化时间的方法,具体步骤如下: [0006] Application of low-field nuclear magnetic resonance measuring method of the present invention proposed thermosensitive hydrogel of the gel time, the following steps:

[0007] 1)对水凝胶体系在不同温度下的凝胶化过程进行低场核磁测定,得到不同时间点水凝胶的横向弛豫时间T2的曲线; [0007] 1) during gelation hydrogel systems at different temperature low-field NMR measurement to obtain transverse relaxation time at different time points T2 hydrogel curve;

[0008] 2)计算T2ffi线的峰的加权平均值,得到T2值随时间变化的曲线; [0008] 2) calculating a weighted average of the peak T2ffi line T2 values ​​obtained versus time curve;

[0009] 3)然后选用双线性回归模型对此曲线进行拟合,确定胶凝点和胶凝时间。 [0009] 3) Then this selection bilinear regression curve fitting to determine the gel point and gel time.

[0010] 优选的,所述水凝胶体系为温敏水凝胶体系。 [0010] Preferably, the aqueous gel system is a temperature sensitive hydrogel systems.

[0011] 优选的,所述步骤1)中凝胶化时间小于20min的水凝胶,凝胶化阶段,取样的时间间隔在2-3min,胶凝后测定的时间间隔为10-20min;凝胶化时间为大于20min的水凝胶,凝胶化阶段,取样的时间间隔在5-10min,胶凝后测定的时间间隔为10-20min。 [0011] Preferably, the step a) the gelling time is less than 20min in a hydrogel, a gel phase, 2-3min sampling time interval, the time interval is measured after gelation 10-20min; Ning a gel time greater than 20min hydrogel, a gel phase, 5-10min sampling time interval, the time interval is measured after gelation 10-20min.

[0012] 优选的,步骤1)使用MultiExpInvAnalysis软件对衰减曲线进行反演,从而得到T2的分布曲线。 [0012] Preferably, the step 1) using software MultiExpInvAnalysis attenuation curve inversion to obtain a T2 distribution curve.

[0013] 本发明中,步骤(2)中会在T2分布曲线上观察到两个峰,分别代表与聚合物链紧密结合的水(IOms附近,T2b)和被束缚在聚合物网络中的水(lOO-lOOOms之间,T21),其中T2b的峰面积很小,且随凝胶化过程的进行没有明显变化,而T21在凝胶化过程中有规律性的变化,所以主要对T21进行研宄。 Water [0013] In the present invention, the step (2) will be observed in the T2 distribution curve, two peaks, representing closely integrated with the polymer chains of the water (near IOms, T2b), and are trapped in the polymer network (between lOO-lOOOms, T21), wherein T2b peak area is small, and the gelation process with no significant change, but changes in the regularity T21 gelation process, the research conducted mainly T21 traitor.

[0014] 优选的,所述判断聚合物网络内水对应的T21峰为1~2分布曲线中lOOms-lOOOms之间的峰。 [0014] Preferably, the aqueous polymer network determines the peak corresponding to peak between T21 lOOms-lOOOms 1 ~ 2 distribution curve.

[0015] 优选的,步骤2)中通过计算每个时间点T21峰的加权平均值来绘制T21值随时间变化的曲线,T21加权平均值的计算公式为T21= 2(X^AiAt),其中xJPAi分别为T21中每个点的横纵坐标,At为曲线中各个点的纵坐标的总和,所述曲线为L形的曲线,该曲线包括一个拐点,该拐点两端均近似于直线。 [0015] Preferably, in step 2) is drawn by a weighted average calculation T21 values ​​for each time point T21 peak versus time curve, calculated as a weighted average T21 T21 = 2 (X ^ AiAt), wherein xJPAi T21 respectively in horizontal and vertical coordinates of each point, At each point is the sum of the ordinates of the curve, the curve is L-shaped curve which includes an inflection point, the inflection point of the two ends are substantially straight.

[0016] 本发明中,步骤(3)中胶凝点和胶凝时间的判断方法为:对T21随时间变化的"L" 型曲线进行拟合,在一定时间范围为选取固定数量的时间点,分别对近似直线的两段进行线性拟合,拟合得到的两条直线有一个交点,这个交点就是胶凝点,其对应的横坐标就是胶凝时间。 [0016] In the present invention, the step (3) and the method of determining the gel point of the gelling time is: For "L" shaped curve fitting of time T21, a time frame is selected in a fixed number of time points , respectively, of the two approximate straight line linear fit obtained by fitting two lines have a point of intersection, the intersection is the gel point, which corresponds to the abscissa is the gel time.

[0017] 相对于传统的方法,本发明所述的方法具有快速准确、非侵入无损害的优势。 [0017] with respect to conventional methods, the method of the present invention has a fast and accurate, non-invasive advantage without damage. 传统的流变学方法需要对凝胶施加旋转剪切,可能会破坏水凝胶的结构和性质,尤其是一些机械强度较弱的水凝胶。 The traditional method requires rheological rotary shear applied to the gel, may damage the structure and properties of hydrogels, especially the hydrogel is mechanically weak. 而传统的倒转试管法无法表征凝胶化的完整过程,只能根据体系流动性判断。 The traditional method can not characterize the complete inversion process tube gelled, only according to the flow of the system is determined. 本发明所述的方法中,T2弛豫时间对凝胶化过程中水分子运动型的变化非常敏感,通过简单快速的测量就可以得到表征凝胶化过程的完整曲线,胶凝点的判断简明快捷, 重复性和稳定性都较好。 The method according to the present invention, it is very sensitive to changes in T2 relaxation time of water molecules during gelation sporty, measured by a simple and rapid characterization curve can be obtained complete gelation process, the gel point determination concise fast, repeatability and stability are better. 更重要的是,此方法不会对整个体系产生任何影响,测定结果更接近于水凝胶的真实状态。 More importantly, this method does not have any impact on the whole system, the measurement result is closer to the true state of the hydrogel. 因此,低场核磁共振法比其他方法具有更多的优势。 Thus, the low-field nuclear magnetic resonance method has more advantages than other methods.

附图说明 BRIEF DESCRIPTION

[0018] 图1为室温下测得的壳聚糖-甘油磷酸二钠温敏水凝胶(CS-GP)的T2曲线。 [0018] FIG. 1 is a chitosan as measured at room temperature - glycerol phosphate disodium thermosensitive hydrogel (CS-GP) T2 of the curve.

[0019] 图2为CS-GP在37°C下的T2曲线随加热时间的变化。 [0019] FIG. 2 is a heating time changes with CS-GP T2 at 37 ° C for graph of.

[0020] 图3为GP浓度为10 %的CS-GP体系T21的加权平均值随时间变化的曲线以及通过对图2的曲线进行拟合得到的胶凝点。 Weighted average over time curve [0020] FIG. 3 is a GP at a concentration of 10% CS-GP system and T21 gelation point fit to a graph obtained by 2.

[0021] 图4为GP含量不同的壳聚糖水凝胶的T2变化曲线。 [0021] FIG. 4 is a distinct change in T2 GP chitosan hydrogel content curve.

[0022] 图5为测得的GP含量不同的水凝胶的凝胶化时间。 [0022] FIG 5 the gel time was measured GP content of different hydrogels.

具体实施方式 detailed description

[0023] 下面结合附图和具体实施例对本发明作进一步说明 Drawings and specific embodiments of the present invention will be further described [0023] below with reference to

[0024] 实施例:壳聚糖-甘油磷酸二钠(CS-GP)温敏水凝胶凝胶化时间的测定 [0024] Example: chitosan - Determination thermosensitive hydrogel gelling time glycerol disodium phosphate (CS-GP)

[0025] 实验材料:GP浓度为7 % -11 %的CS-GP体系。 [0025] Experimental materials: GP concentration of 7% to 11% CS-GP system.

[0026] 实验仪器:匪120-Analyst,磁场强度大于0. 05T,共振频率为2MHz-3MHz,磁极直径大于160mm,磁体温度控制在31. 99-32. 00°C。 [0026] Experimental Instrument: bandit 120-Analyst, the magnetic field strength is greater than 0. 05T, a resonance frequency of 2MHz-3MHz, pole diameter greater than 160mm, the magnet temperature is controlled at 31. 99-32 00 ° C..

[0027] (1)样品制备:在冰浴和搅拌的条件下,向用0.IM盐酸溶解的2%壳聚糖溶液中缓慢滴加50 %的GP,制备壳聚糖浓度1. 6 %。 [0027] (1) Sample preparation: under ice-cooling and stirring, hydrochloric acid dissolved 0.IM Into a 2% chitosan solution was slowly added dropwise 50% of the GP, preparing chitosan concentration of 1.6% . GP浓度为7 % -11 %的CS-GP温敏体系,测定pH 值后于4°C保存备用。 GP concentration of 7% to 11% CS-GP temperature sensitive system, measuring the pH value at 4 ° C after use.

[0028] (2)样品在加热过程中! [0028] (2) the samples during heating! ^图谱的测定:取2mlCS-GP溶液于底面直径为IOmm的核磁管中,设置好仪器参数后先测定室温下CS-GP体系的T2图谱(图1),然后将样品置于37°C水浴中加热,并在固定的时间点取出,测定核磁信号衰减曲线并进行反演,得到1~2曲线。 ^ Measured map: 2mlCS-GP solution was taken to the bottom of the NMR tube having a diameter of IOmm in the first measuring instrument parameters set T2 spectrum (FIG. 1) CS-GP system at room temperature, the samples were then placed in a water bath at 37 ° C heated and removed at fixed time points measured NMR signal decay curve and inversion, to obtain 1 to 2 curve. 图2为含10%GP的CS-GP体系在37°0下T2图谱随时间的变化。 FIG 2 is a CS-GP system containing 10% GP change with time in the 37 ° 0 T2 spectrum. 随时间的延长,T21逐渐左移。 With time, T21 gradually left.

[0029] (3)通过计算每个时间点T2曲线中T21峰的加权平均值,可以绘制T21随时间变化的曲线。 [0029] (3) by a weighted average calculation for each time point T2 peak curve T21, T21 can be plotted versus time curve. 对于每个样品,都在160min内取12个点作图,得到图2所示的曲线。 For each sample, 12 have taken the points plotted in 160min, resulting curves shown in FIG.

[0030] (4)如图3所示,应用双线性回归模型对图2的曲线进行拟合,即对曲线拐点两端分别进行线性拟合,这两条直线有一个交点,这个交点就是胶凝点。 [0030] (4) As shown in FIG Bilinear regression curve 3 of FIG 2 is fitted, i.e. both ends of the linear fit curve of inflection points, respectively, the two lines have a point of intersection, the intersection is the gel point. 胶凝点对应的横坐标就是凝胶化时间。 Gel point corresponding to the abscissa is the gelation time.

[0031] (5)应用此方法,可以测定GP含量不同的CS-GP温敏体系的1变化曲线,并可以得到对应的凝胶化时间。 [0031] (5) by this method, a curve can be measured in different levels of CS-GP GP temperature sensitive system, and can obtain the corresponding gel time.

[0032]表1 : [0032] Table 1:

[0033] [0033]

Figure CN104764763AD00051

[0034] 以上所述,仅为本发明较佳的具体实施方式,但本发明的保护范围并不局限于此, 任何熟悉该技术的人在本发明所揭露的技术范围内,可轻易想到的变化或替换,都应涵盖在本发明的保护范围之内。 [0034] above, the present invention is merely preferred specific embodiments, but the scope of the present invention is not limited thereto, and any person skilled in the art within the technical scope disclosed by the present invention can be easily thought of changes or replacements shall fall within the protection scope of the present invention.

Claims (6)

  1. 1. 一种应用低场核磁共振弛豫技术测定凝胶化时间的方法,所述方法包括: 1) 对水凝胶体系在不同温度下的凝胶化过程进行低场核磁测定,得到不同时间点水凝胶的横向弛豫时间! A method of application of low-field NMR relaxation Determination of the gelation time, the method comprising: 1) the process of gelation hydrogel systems at different temperature low-field NMR measurement, obtained at different times transverse relaxation time point hydrogel! ^的曲线; 2) 计算!^曲线的峰的加权平均值,得到T2值随时间变化的曲线; 3) 然后选用双线性回归模型对此曲线进行拟合,确定胶凝点和胶凝时间。 ^ Curve; 2) calculating a weighted average of the peak of the curve ^ to obtain the value of T2 versus time curve;! 3) then this selection bilinear regression curve fitting to determine the gelation time and gel point .
  2. 2. 根据权利要求1所述的方法,其特征在于,所述步骤2)包括: 采用CPMG序列测定水凝胶体系未加热前和在不同温度下加热不同时间的核磁共振衰减曲线,通过将核磁共振信号衰减曲线进行反演,获得T2分布曲线; 选取聚合物网络内的水对应的T2峰来计算T2的加权平均值,并以此T2值对时间做图; 所述T2的加权平均值T21按如下方式计算,T21= 2 (xi*Ai/At),其中xi和Ai分别为T2中每个点的横纵坐标,At为曲线中各个点的纵坐标的总和。 2. The method according to claim 1, wherein said step 2) comprises: hydrogel systems was measured before heating and non-heating NMR at different times at different temperatures using CPMG sequences decay curve, by NMR decay curve inversion resonance signals obtained T2 distribution curves; selecting the corresponding water within the polymer network to calculate a weighted average of the peak T2 and T2, and thus the value of T2 versus time graph; T2 weighted average of the T21 calculated as follows, T21 = 2 (xi * Ai / At), where xi and Ai respectively T2, horizontal and vertical coordinates of each point, At is the sum of the individual points in the curve ordinate.
  3. 3. 根据权利要求1或2所述的方法,其特征在于,所述步骤3)包括: 分别对步骤2)得到的T2值随时间变化的曲线的两端进行线性拟合,得到两条直线,两条直线的交点为凝胶点,其相应的横坐标为凝胶化时间。 3. The method of claim 1 or claim 2, wherein said step 3) comprises: two ends T2 values, respectively in step 2) to give a time-varying linear curve fitting to obtain two straight lines , intersection of the two straight lines as the gel point, the corresponding abscissa is the gelation time.
  4. 4. 根据权利要求1或2所述的方法,其特征在于:所述判断聚合物网络内水对应的T21 峰为T2分布曲线中lOOms-lOOOms之间的峰。 4. The method of claim 1 or claim 2, wherein: said polymer network water Analyzing the peak corresponding to peak between T21 lOOms-lOOOms T2 distribution curve.
  5. 5. 根据权利要求1或2所述的方法,其特征在于:所述步骤1)中凝胶化时间小于20min 的水凝胶,凝胶化阶段,取样的时间间隔在2-3min,胶凝后测定的时间间隔为10-20min;凝胶化时间大于20min的水凝胶,凝胶化阶段,取样的时间间隔在5-10min,胶凝后测定的时间间隔为10_20min。 5. The method of claim 1 or claim 2, wherein: in step 1) the gelation time is less than 20min hydrogel, a gel phase, the sampling interval in 2-3min, gelling after the measurement time interval for 10-20min; 20min gelation time is greater than a hydrogel, a gel phase, 5-10min sampling time interval, the time interval is measured after gelation 10_20min.
  6. 6. 根据权利要求1所述的方法,其特征在于,所述水凝胶体系为温敏水凝胶体系。 6. The method according to claim 1, wherein the hydrogel is temperature sensitive system hydrogel systems.
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