RESUMEN
As an important drug carrier, liposome has the advantages of high biocompatibility and low immunogenicity. It has been widely used in the field of drug delivery, especially the targeted treatment of tumors. However, traditional liposomes are composed of flowing dynamic phospholipid membranes, which are easy to fuse together, resulting in aggregation and drug leakage. In addition, the lower degree of polyethylene glycol (PEG) modification also limits the targeted delivery performance of the vector in vivo. In view of the problems, a nanoparticle-targeted drug delivery system combining the inorganic carrier calcium phosphate with liposomes was designed, namely lipid calcium phosphate (LCP). Using doxorubicin (DOX) as a model drug, doxorubicin-loaded lipid calcium phosphate nanoparticles (DOX/LCP) were prepared by reverse microemulsion method, and the preparation conditions were investigated. The structure and morphology of calcium phosphate cores were observed by infrared spectroscopy, EDS spectroscopy, and transmission electron microscopy. The particle size, encapsulation efficiency, drug loading, stability and release behavior in vitro of DOX/LCP were investigated. Confocal microscopy and flow cytometry were used to qualitatively and quantitatively evaluate the uptake of DOX in drug-resistant tumor cell line MCF-7/DOX by LCP, respectively, and the thiazolium MTT colorimetric method was used to examine its cytotoxicity. LCP exhibited a typical core-shell structure with good size uniformity and dispersibility. The particle size was in (48.6 ±3.9) nm, the potential was in (−12.1 ±1.2) mV, and the encapsulation efficiency was above 80%. Moreover, it has a good stability in simulated plasma. In vitro release of LCP had a significant pH dependence. When the pH of the environment was 7.4, the cumulative release within 24 hours was less than 20%; as the pH of the release medium decreases, the release rate of DOX/LCP was accelerated gradually. Accumulated release over 24 hours exceeded 90% in the pH 4.5 medium. LCP significantly promoted the uptake and accumulation of DOX by drug-resistant cells, and the inhibition rate of drug-resistant tumors was significantly increased in vitro. The half maximal inhibitory concentrations (IC50) of LCP/DOX and free DOX were 4.6 and 11.8 μg·mL−1, respectively, and there was a significant difference between the two groups (P < 0.05). In summary, the LCP prepared in this study had a small particle size, high encapsulation efficiency and good stability. It had environmental responsiveness and potential inhibition of tumor drug resistance, which suggests a potential in the clinical application.
RESUMEN
It is a challenging and important project to prolong the in vivo half life of protein and peptide drugs by physicochemical methods without new molecular entities generation. Protein crystallization provides a new strategy for improving the stability and in vivo delivery of these drugs. We show here that recombinant human interferon-alpha (rhIFN) can form spherical crystals. The physical and chemical features of the crystals were characterized, and drug dissolution was determined in vitro. The pharmacokinetics of crystallized interferon after sc injection in rabbit at 1.5 x 10(7) U x kg(-1) was compared to that of soluble form. The crystals were characterized as mono-dispersed spheres, with yield of > 80%, mean diameter size of about 16 microm and crystallinity of 23.2%. The in vitro dissolution behavior of crystallized rhIFN was featured as low initial burst release (21% within the first 2 h) and prolonged cumulative dissolution time up to 72 h without biological potency lost. After sc administration of soluble and crystallized interferon in rabbits, the peak time (T(max)) and half life (t1/2) were prolonged from (1.80 +/- 0.45) h and (1.35 +/- 0.35) h to (13.20 +/- 2.68) h and (10.68 +/- 1.97) h, respectively. The corresponding peak concentration decreased from (1 411.10 +/- 575.28) U x mL(-1) to (721.37 +/- 206.55) U x mL(-1). PK/PD analysis indicated that (96.87 +/- 20.30) % of relative bioavailability was obtained. The research results of this work will provide important academic value and application prospect for improving clinical therapeutic effect and development of biomacromolecules delivery system for protein and peptide drugs.