Different from previously reported co-amorphous systems, a co-amorphous curcumin-magnolol (CUR-MAG CM) system, as compared with its crystalline counterparts, exhibited decreased dissolution due to its aggregation during dissolution. The main purpose of the present study is to deaggregate CUR-MAG CM to optimize drug dissolution and explore the deaggregation mechanism involved. Herein, a small amount of polymer (HPMC, HPC, and PVP K30) was co-formulated at 5% (w/w) with CUR-MAG CM as ternary co-amorphous systems. The polymer addition changed the surface properties of CUR-MAG CM including improved water wettability enhanced surface free energy, and hence exerted a deaggregating effect. As a result, the ternary co-amorphous systems showed faster and higher dissolution as compared with crystalline CUR/MAG and CUR-MAG CM. In addition, the nucleation and crystal growth of dissolved CUR and MAG molecules were significantly inhibited by the added polymer, maintaining a supersaturated concentration for a long time. Furthermore, polymer addition increased the Tgof CUR-MAG CM, potentially involving molecular interactions and inhibiting molecular mobility, resulting in enhanced physical stability under 25 °C/60% RH and 40 °C/75% RH conditions. Therefore, this study provides a promising strategy to optimize the dissolution and physical stability of co-amorphous systems by deaggregation and crystallization inhibition via adding small amounts of polymers.Keywords:curcumin;magnolol;co-amorphous;deaggregation;dissolution;physical stability
A competitive colorimetric assay has been established to detect chloramphenicol (CAP). It is based on the use of colloidal and electrostatically stabilized aptamer-modified gold nanoparticles (GNPs). The CAP aptamer is modified by a sequence of 5 adenosine groups to anchor it on the surface of GNPs. It can competitively capture two compounds, viz. D-(-)-threo-2-amino-1-(4-nitrophenyl)-1,3-propanediol (CAP-base, with a positive charge) and CAP (which is uncharged). The capture of the positively charged CAP-base triggers the aggregation of modified GNPs in salt-containing solution, and this causes a color change from red to purple. However, in the presence of CAP and CAP-base, the capture of the uncharged CAP weakens this color change by a competing process for capture. Thus, the concentration of CAP is associated with the degree of deaggregation of GNPs and can be quantified by the ratio of absorbances at 620 nm and 520 nm. The assay has a 22 nM limit of detection in acidic solution, and the response is linear in the range of 0.20 to 3.20 μM CAP concentration. This assay was successfully applied to the determination of CAP in spiked environmental water samples. Conceivably, this method has a wide scope in that it may be applied to a wide range of analytes if respective aptamers are available.
Schematic presentation of a competitive non-cross linking deaggregating method for detecting chloramphenicol. The surface charge of polyA-Apt@GNPs and its aggregation degree (purple) are determined by the charge of target. (CAP-base: precursor of CAP; PolyA-Apt@GNPs: 5′-polyA-modified DNA aptamer functionalized gold nanoparticles.)
危险品化学品经营许可证（带存储）