Abstract
In this work, the synthesis and the aqueous solution self-assembly behavior of novel partially hydrophobically modified poly(2-(dimethylamino) ethyl methacrylate)-b-poly(oligo(ethylelene glycol) methyl ether methacrylatetabel) pH and temperature responsive random diblock copolymers (P(DMAEMA-co-Q6/12DMAEMA)-b-POEGMA), are reported. The chemical modifications were accomplished via quaternization with 1-iodohexane (Q6) and 1-iodododecane (Q12) and confirmed by 1H-NMR spectroscopy. The successful synthesis of PDMAEMA-b-POEGMA precursor block copolymers was conducted by RAFT polymerization. The partial chemical modification of the diblocks resulted in the permanent attachment of long alkyl chains on the amine groups of the PDMAEMA block and the presence of tertiary and quaternary amines randomly distributed within the PDMAEMA block. Light scattering techniques confirmed that the increased hydrophobic character results in the formation of nanoaggregates of high mass and tunable pH and temperature response. The characteristics of the aggregates are also affected by the aqueous solution preparation protocol, the nature of the quaternizing agent and the quaternization degree. The incorporation of long alkyl chains allowed the encapsulation of indomethacin within the amphiphilic diblock copolymer aggregates. Nanostructures of increased size were detected due to the encapsulation of indomethacin into the interior of the hydrophobic domains. Drug release studies demonstrated that almost 50% of the encapsulated drug can be released on demand by aid of ultrasonication.
Highlights
Amphiphilic block copolymers (AmBCs) have gained extensive scientific interest over the last decades in studies regarding the synthesis of novel materials, by employing facile polymerization techniques, along with the at-length apperception of their behavioral features allowing for their utilization in a broad field of applications [1,2]
We report on the synthesis of poly(2-(dimethylamino) ethyl methacrylate)b-poly((oligo ethylene glycol methyl ether methacrylate) (PDMAEMA-b-POEGMA) double hydrophilic diblock copolymers by utilizing sequential Reversible addition fragmentation chain transfer polymerization (RAFT) polymerization [43] and their subsequent partial hydrophobic chemical modification by quaternization reaction with iodohexane and iodododecane to produce novel P(DMAEMA-co-Q6DMAEMA)-bPOEGMA and P(DMAEMA-co-Q12DMAEMA)-b-POEGMA random diblock copolymers, respectively
PDMAEMA56 and PDMAEMA42 homopolymers were utilized as the macro-CTAs for the synthesis of PDMAEMA56-b-POEGMA86 and PDMAEMA42-b-POEGMA12 diblock copolymers respectively
Summary
Amphiphilic block copolymers (AmBCs) have gained extensive scientific interest over the last decades in studies regarding the synthesis of novel materials, by employing facile polymerization techniques, along with the at-length apperception of their behavioral features allowing for their utilization in a broad field of applications [1,2]. The most fascinating feature of AmBCs is the formation of nanosized structures via self-assembly processes when inserted in aqueous media and their potential implementation in nanotechnology based concepts [3,4,5]. This impressive ability along with other capacities, such as the structural adjustment to surrounding media, the response to physicochemical stimuli and the interaction with biomolecules, ensures the eligibility of AmBCs for advanced biomedical applications, such as gene and drug delivery, and theranostics [6,7]. When the hydrophobic content increases, intermolecular self-assembly occurs and multichain aggregates are formed [13,14,15,16]
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