[Effect of ipriflavone on reconstruction of periodontal tissues during recurrence of orthodontic teeth in rats].

PURPOSE: To investigate the effect of ipriflavone on reconstruction of periodontal tissues during recurrence of orthodontic teeth. METHODS: Twenty-four male SD rats were randomized into 2 groups, ipriflavone group(IP group) and control group, there were 12 rats in each group. The model of recurrence after movement of orthodontic teeth in rats was established. After continuous loading for 10 days, the loading devices were removed. Rats in ipriflavone group (IP group) were given ipriflavone intragastrically for 10 mg/(kg·d) after the devices were removed, while rats in the control group were given an equivalent amount of normal saline after the devices were removed. On the 0th, 1st, 3rd, 7th, and 10th day of administration, the rat maxillary impression and plaster model of two groups were prepared under local anesthesia, the distance between maxillary first molar lingual sulcus point and third molar in lingual groove point was measured to evaluate the relapse distance. After drug infusion for 10 days, the collected tissue specimens were stained with H-E to observe periodontal reconstruction, and expression of bone morphogenetic protein-2(BMP-2) was detected by immunohistochemical staining. Software Image-Pro 6.0 was used to analyze the optical density values of the stained sections. The data were analyzed with SPSS 22.0 software package. RESULTS: After removing the orthopaedic devices for 10 days , there was a significant recurrence of the movement of the orthodontic teeth in both groups. The recurrent distance of IP group was significantly smaller than that of the control group, and still significantly smaller than that of the control group at 10 d. H-E staining and immunohistochemical staining results showed that the IP group had more new bone formation and more BMP-2 expression in the periodontal tissues compared to the control group in vivo. CONCLUSIONS: In the process of recurrence of orthodontic tooth movement, ipriflavone can promote the expression of BMP-2 in periodontal tissue, improve bone remodeling of periodontal tissue, and effectively reduce the recurrent rate of orthodontic tooth movement.

Stereocomplexation Assisted Assembly of Poly(γ-glutamic Acid)-graft-polylactide Nano-micelles and Their Efficacy as Anticancer Drug Carrier.

BACKGROUND: Micelles as drug carriers are characterized by their inherent instability due to the weak physical interactions that facilitate the self-assembly of amphiphilic block copolymers. As one of the strong physical interactions, the stereocomplexation between the equal molar of enantiomeric polylactides, i.e., the poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA), may be harnessed to obtain micelles with enhanced stability and drug loading capacity and consequent sustained release. AIMS/METHODS: In this paper, stereocomplexed micelles gama-PGA-g-PLA micelles) were fabricated from the stereocomplexation between poly(gama-glutamic acid)-graft-PLLA gama-PGA-g-PLA) and poly(gamaglutamic acid)-graft-PDLA gama-PGA-g-PLA). These stereocomplexed micelles exhibited a lower CMC than the corresponding enantiomeric micelles. RESULT: Furthermore, they showed higher drug loading content and drug loading efficiency in addition to more sustained drug release profile in vitro. In vivo imaging confirmed that the DiR-encapsulated stereocomplexed gama-PGA-g-PLA micelles can deliver anti-cancer drug to tumors with enhanced tissue penetration. Overall, gama-PGA-g-PLA micelles exhibited greater anti-cancer effects as compared with the free drug and the stereocomplexation may be a promising strategy for fabrication of anti-cancer drug carriers with significantly enhanced efficacy.

pH triggered re-assembly of nanosphere to nanofiber: The role of peptide conformational change for enhanced cancer therapy.

pH-triggered conformational change and subsequent re-assembly of nanostructures provide a new strategy in nanomedicine for controlled drug release and enhanced therapy. Here, we reported the development of a novel pH-responsive nano-assembly as a drug carrier from peptide amphiphile (PA) consisting of mimicking peptide and stearic acid moieties. The mimicking peptide is a basic 17-amino acid peptide derived from antennapedia homeodomain, and undergoes a conformational transition of the secondary structure from ß-sheet at pH7.4 to α-helix at pH5.0. Such transition therefore leads to simultaneous evolution of the self-assembled structure of PA from nanosphere to nanofiber, promotes assemblies retention and then release drugs in the cytoplasm of tumor cell. In vitro studies showed that the doxorubicin (Dox)-loaded PA nanoparticle (PA@Dox) could be uptaken efficiently by the cell due to the membrane penetrating capability of the mimicking peptide and subsequently the released Dox further induce apoptosis of murine colon carcinoma CT26 (MCCC) cell. In a mouse xenograft model of MCCC, administration of PA@Dox via lateral tail vein injection could remarkably retard the tumor growth. The overall results suggested that the PA-based nanocarriers adopting the novel strategy of pH-triggered secondary structural change could enhance therapeutic efficacy and be used as a promising platform for potential development of new generation of drug carriers for cancer therapy.

Poly(γ-glutamic acid) modulates the properties of poly(ethylene glycol) hydrogel for biomedical applications.

In this paper, a series of copolymer hydrogels were fabricated from methacrylated poly(γ-glutamic acid) (mPGA) and poly(ethylene glycol) diacrylate (PEGDA). The effect of ionic strength and pH on the swelling behavior and mechanical properties of these hydrogels were studied in detail. Release of Rhodamine B as a model drug from the hydrogel was evaluated under varied pH. In vitro photoencapsulation of bovine cartilage chondrocytes was performed to assess the cytotoxicity of this copolymer hydrogel. The results revealed that the copolymer hydrogel is ionic- and pH-sensitive, and does not exhibit acute cytotoxicity; this copolymer hydrogel may have promising application as matrix for controlled drug release and scaffolding material in tissue engineering.