Hyperbranched Polymer-Drug Conjugates with High Drug Payload for Enhanced Cellular Delivery

Abstract

Purpose. To synthesize and evaluate hyperbranched polymer (HBP)-drug conjugates with high drug payload for enhanced cellular delivery. Methods. Polyol-and polyglycerol-ibuprofen conjugates with or without imaging agent fluorescein isothiocyanate (FITC) were synthesized using dicyclohexilcarbodiimide (DCC) as a coupling agent. Drug-polymer conjugates were characterized using 13 C NMR, 1 H NMR, and gel permeation chromatography (GPC). Stability of the drug-conjugates was studied using free drug release through a dialysis membrane. Cellular entry of FITC-labeled HBP conjugates was studied using fluorescence activated cell sorter (FACS), and cell supernatant was analyzed by UV-visible spectrophotometer. The intracellular localization of FITC-labeled conjugates in A549 lung epithelial cells was imaged using fluorescence microscopy. Anti-inflammatory activity of the HBP-ibuprofen conjugates was estimated in vitro by measuring the concentration of prostaglandin (PGE 2 ) using an ELISA kit. Results. The average number of ibuprofen molecules conjugated per molecule of HBP was estimated to be 50 for polyol and 53 for polyglycerol. The HBP-drug conjugates did not release the drug up to 72 h in methanol, indicating the presence of stable ester bonds. Both the polymer-drug conjugates entered the cells rapidly. The conjugates were localized in the cell cytosol as evidenced by fluorescence microscopy. Within 30 min, the HBP-drug conjugates showed rapid suppression of PGE 2 synthesis, whereas free ibuprofen did not show any activity. At later times, the conjugates showed comparable activity. Conclusions. For the first time, we report HBP conjugates with a high drug payload. HBP-drug conjugates entered the cells rapidly and produced the desired pharmacological action. This study demonstrates that hyperbranched polyol and polyglycerol are promising nanovehicles for achieving enhanced cellular delivery of drugs.

Association of a Weakly Acidic Anti-Inflammatory Drug (Ibuprofen) with a Poly(Amidoamine) Dendrimer as Studied by Molecular Dynamics Simulations

“…Concerning the charging state of ibuprofen at different pH conditions, it has been found that at high pH conditions (pH > 10.5), ibuprofen becomes fully ionized (due to deprotonation of the -OH of the carboxyl group), whereas at low pH conditions (pH < 2), it remains neutral. 14,21 Moreover, it was observed that the maximum load of ibuprofen molecules per dendrimer was realized when the drug was at its ionized state; that is, at a high pH environment. 14,21 Specifically, it was demonstrated 21 that for systems consisting of G3 PAMAM dendrimers, the maximum number of associated drug molecules per dendrimer did not exceed that of the primary amine groups of the dendrimer; that is, 32, regardless of the amount that was initially included in the solution.…”

“…14,21 Moreover, it was observed that the maximum load of ibuprofen molecules per dendrimer was realized when the drug was at its ionized state; that is, at a high pH environment. 14,21 Specifically, it was demonstrated 21 that for systems consisting of G3 PAMAM dendrimers, the maximum number of associated drug molecules per dendrimer did not exceed that of the primary amine groups of the dendrimer; that is, 32, regardless of the amount that was initially included in the solution. Taking into account the above experimentally available information, we have constructed models consisting of a G3 PAMAM dendrimer in different protonation states, water, and 32 ibuprofen molecules, as described in Table 1.…”

“…22 Recent experiments have demonstrated that complexation of ibuprofen with PAMAM dendrimers not only can promote the solubilization of the drug but may increase its cellular uptake as well. 21,25,26 It therefore represents an interesting system with good prospects for pharmaceutical uses, and a better understanding of the mechanisms involved in the complexation may offer valuable information toward setting a more general framework in the study of PAMAM/hydrophobic acidic drug systems.…”

Structure, phase behavior, and inhomogeneous fluid properties of binary dendrimer mixtures

“…[1][2][3][4][5] A dendrimer with n generations of monomers is denoted a Gn dendrimer. Dendrimers have numerous technological applications, for example, in the targeted delivery of drugs 6,7 and, in particular, anticancer agents, [8][9][10] in light-harvesting applications, 11 and also as a tool for the development of nonviral gene delivery. 12 In a dendrimer solution, the individual macromolecules feature different conformations due to fluctuations of the monomers.…”

The Newborn Drug Development Initiative

“…A workshop is being planned as part of this initiative that will identify scientific issues for the development of pediatric formulations, new methods of drug delivery (eg, use of dendrimers and inhalation devices for drug delivery in young infants, [37][38][39] economic barriers, research on taste and flavor preferences in infants and children, and methods to facilitate the development and approval of pediatric formulations.…”