Abstract
Micelles are self-assembled nanoscaled aggregates from amphiphilic unimers and can be used to encapsulate hydrophobic drugs. However, the dynamic exchanging of unimers between micelles and bulk solution often leads to micelle destabilization and subsequent leaking of the encapsulated substances. Thus, we incorporated a hydrophobic polymer into the micellar core for interlacing the unimers and stabilizing the micelle structure. The polymer-stabilized and non-polymer-stabilized micelles have similar physicochemical properties including small sizes (~35 nm), negative surface charges (~−35 mV), and high drug contents (~15%). Drugs encapsulated in polymer-stabilized micelles are released in a slower rate than are non-polymer-stabilized micelles. From in vivo pharmacokinetic studies, drugs loaded in polymer-stabilized micelles have lower clearance and higher plasma concentration and lower volume distribution than non-polymer-stabilized micelles have. In conclusion, polymer-stabilized micelles can reduce rapid drug clearance via strengthening of the micellar structure and increase in the available drug amount in plasma, thus broadening pharmaceutical applications of micelles.
Highlights
Nanotechnology is widely employed in drug delivery systems (DDSs) [1, 2]
Clarithromycin (CL), roxithromycin (ROX), poly(D,L-lactic-co-glycolic acid) (PLGA, lactide : glycolide = 50 : 50, MW 40 kD–75 kD), ammonium acetate, potassium dihydrogen phosphate, phosphoric acid, phosphatebuffered saline (PBS), xylazine, and formic acid were purchased from Sigma-Aldrich (Saint Louis, MO, USA) and used as supplied. 1,2-Distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] (PEGPE) was purchased from Avanti Polar Lipids (Alabaster, AL, USA)
To understand how much PLGA should be incorporated to stabilize micelle structure, P-MCLs with different PLGA/PEG-PE feeding ratios were prepared and incubated in 10% Fetal bovine serum (FBS). Their size changes were monitored by DLS (Figure 2) to examine the stability of P-MCLs over time
Summary
Nanotechnology is widely employed in drug delivery systems (DDSs) [1, 2]. In order to improve drug availability and to overcome the barriers of the biological system, the DDSs are generally designed to have sizes falling within the range of 1–100 nm [3]. PEG-PE micelle sizes can be adjusted from 7 nm to 40 nm by altering PEG with different lengths [16]. These aforementioned small size and PEGylated surface make PEG-PE micelles able to accumulate in subcutaneous tumour [17] or the infract zone [18]. The PEG-PE micelles can be further modified with a functional group or antibody moiety on the surface to enhance their targeting efficiency [19]. PEG-PE micelles possess advantages such as small size, high solubility for hydrophobic drugs, low CMC, sustained release of drugs, targeting delivery, and potential for sterilization by filtration [20] for being a promising drug carrier [11]
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