农药纳米混悬剂及其制备方法探析

Progress on pesticide nanosuspension and its preparation methods

纳米混悬剂是指药物有效成分以晶体或无定型状态,在表面活性剂的作用下,均匀分散至水中形成的稳定的纳米胶态分散体系。纳米混悬剂可增大难溶性药物的溶解度,提高药物的渗透性、生物活性及利用率。文章就纳米混悬剂的几种主要制备方法及其在医药和农药领域的研究应用进展进行了综述,初步分析了其贮存稳定性并就其未来发展进行了总结展望。农药纳米混悬剂制备方法主要有两种——自上而下法和自下而上法。其中自上而下法包括介质研磨法、活塞-裂缝均质化法和高压微射流法;自下而上法包括控制沉淀法和超临界流体法。自上而下法适用于疏水、疏油型农药原药的加工,其制备过程简单,易于扩大生产;缺点是其中的介质研磨法在研磨过程中也会出现介质腐蚀,易造成样品污染,活塞-裂缝均质化法则须预先将药物微粉化。自下而上法的优点是设备简单、耗能低,但要求农药原药需至少能溶解于1种溶剂中。介于各方法均有其优缺点,在实际应用中也会将几种方法结合使用。基于目前农药使用中存在的有效利用率低的问题,探析纳米混悬剂作为一种新型农药剂型的应用前景具有重要的现实意义。

Nanosuspensions are nano-colloidal dispersions of drug particles in crystal or amorphous state stabilized by surfactants. Nanosuspensions not only solve the problem of poor solubility,but also improve permeability, biological activity and efficacy of drug. The preparative technique nanosuspensions and its applications in the field of medicine and pesticide w ere review ed. Furthermore,the storage stability and future development of nanosuspension have also been preliminarily analyed.The pesticide nanosuspensions can be produced either by top-dow n approach such as media milling,piston-gap homogenization and high pressure microfluidization or by bottom-up technique such asprecipitation and supercritical fluid method. Top-dow n method is suitable for hydrophobic and oleophobic pesticide processing,and the preparation process is simple and easy to scale up. How ever,the media milling process suffers from the corrosion of the media,w hich results in the pollution of the samples and the pre-micronization of the samples is necessary for the piston-gap homogenization method. Bottom-up method has the advantages of low instrumental requirements and low energy consumption,but this method requires the pesticide to be soluable in at least one solvent. Because each method has its advantages and disadvantages,the combination of several methods has been applied in the preparation of nanosuspensions. Based on the low effective issues associated w ith the pesticide use,exploring the application prospect of nanosuspensions as a new type of pesticide formulation is crucial and has potential practical applications.