Preparation Of Calcium Alginate Microspheres By An Electrospraying Method For Chemoembolization

Transcatheter arterial chemoembolization(TACE)has a high survival benefit due to the combination of local chemotherapy and ischemic necrosis induced by arterial embolization.It is recommended as the first choice for the treatment of advanced primary liver cancer.With the development of TACE,drug-eluting bead(DEB)have become a research hotspot.Sodium alginate(NaAlg)is a natural polysaccharide that has been widely used in the field of biomedical materials because of its good biocompatibility,bioadhesion,non-toxicity and degradability.Electrospraying is a simple and environmentally friendly technique involving only the aqueous phase.By controlling the electrospray parameters,such as the voltage and the size of the spinneret,the particle size and surface topography of the formed particles are controlled to produce microspheres of a certain particle size range.In view of the lack of basic research on calcium alginate(CaAlg)gel microspheres and the lack of reference for the selection of calcium alginate embolization microspheres of different sizes and properties during chemoembolization,this paper aims to make up for the lack of research in this direction and provide relevant reference.A variety of CaAlg microspheres with different particle sizes and morphologies were prepared by electrospraying technology and characterized by optical microscopy.The influences of electrospray parameters on the particle size and morphology of the calcium alginate microspheres were studied,the type of NaAlg(named 126 and 128),the concentration of NaAlg solution,the flow rate of NaAlg solution,the size of the spinneret and the nozzle voltage.The microspheres of a certain particle size range were selected to load the anti-cancer drug DOX by the ion-exchange adsorption method(named DOX@CaAlg microspheres),the concentration of DOX solution before and after adsorption were determined by fluorescence analyzer to estimate the drug-loading amount,and the drug-loading behavior was studied.The drug release behavior of DOX@CaAlg microspheres was studied by direct release method.Biocompatibility of CaAlg microspheres,in vitro cytotoxicity of DOX@CaAlg microspheres and the sterilization process of CaAlg microspheres were studied.The results are as follows.(1)The results of preparation and morphology characterization of CaAlg microspheres show that the diameter of the microspheres prepared by this method is130~1600 ?m in a certain range of electrospray parameters.The microspheres show good sphericity when the concentration of electrosprayed solution is moderate(2%,2.5%(w/w)).When the concentration of electrosprayed solution is too low,it is easy to produce convex and broken microspheres.When the concentration is too high,elliptical microspheres are formed at high voltage.When other electrospray parameters are the same,the microspheres prepared with the 126 type NaAlg at the same electrospray concentration are smaller than the microspheres prepared with the 128 type NaAlg.The lower the concentration of the NaAlg solution(the range of study is 1%,1.5%,2%,2.5% and 3%(w/w)),the faster the flow rate of the NaAlg solution(the range of study is 0.5 mL/h,1mL/h,2 mL/h,4 mL/h,6 mL/h,10 mL/h,15 mL/h and 20 mL/h)and the smaller the size of the spinneret(the range of study is 18,22 G,25 G,28 G and 30 G),the smaller the particle size of the prepared microspheres.When the concentration of NaAlg is moderate,the particle size of the microspheres is not much different in the low voltage region of 10kV~16 kV,and followed is the transition region of 18 kV~22 kV.At this stage,the electrospraying process becomes unstable and the dispersity of particle size is large.In the high voltage region of 24 kV~30 kV,the electrospraying process becomes stable again and the distribution of particle size is narrow.(2)The drug-loading behavior of the CaAlg microspheres shows that under the same dosage,the smaller the particle size of the microspheres,the faster the drug loading rate and the higher the encapsulation efficiency.The optimum drug loading efficiency of the microspheres(particle size 180 ?m)is explored.The maximum drug loading of the microspheres is 182 mg DOX/mL CaAlg microspheres at the optimum dosage of 240 mg DOX/mL CaAlg microspheres,and the encapsulation efficiency is 63%.(3)The release behavior of the DOX@CaAlg microspheres indicates that the lower the pH of the release solution PBS,the smaller the particle size of the drug-loaded microspheres,and the lower the concentration of the electrospray NaAlg,the faster the release rate of the drug-loaded microspheres and the higher the total release amount.(4)The results of biocompatibility experiments show that the biocompatibility of CaAlg microspheres is excellent.(5)The results of in vitro cytotoxicity experiments show that the higher the drug loading amount of DOX@CaAlgmicrospheres,the smaller the particle size,the lower the electrospray NaAlg concentration,and the stronger the cytotoxicity to BEL-7402 cells.(6)The sterilization process of CaAlg microspheres shows that the quality difference of microspheres is not obvious before and after sterilization,and the particle size of microspheres becomes smaller after sterilization.The results of this study can provide reference for the selection of calcium alginate microspheres with different sizes and properties during chemoembolization to adapt to different embolization needs.Furthermore,it lays the foundation for the application of the calcium alginate microspheres in the field of chemoembolization.