Langmuir−Blodgett Films of Biocompatible Poly(HPMA)-block-poly(lauryl methacrylate) and Poly(HPMA)-random-poly(lauryl methacrylate): Influence of Polymer Structure on Membrane Formation and Stability

Abstract

Membranes based on functional biocompatible polymers can be regarded as a useful model system to study biological interactions, e.g. antibody-antigen interactions or protein polymer interactions. These model systems may give a better insight into these processes and may help to find suitable polymeric structures offering biocompatibility as well as reduced polymer protein interaction. In this respect, Langmuir-Blodgett (LB) layer formation at the air/water (A/W) interface is studied in respect to polymer architecture in this article. For this purpose, narrowly distributed N-(2-hydroxypropyl)-methacrylamide (HPMA) random and block copolymers have been prepared by the RAFT polymerization method. For random copolymers different molecular weights were prepared. As for the block copolymers also the ratio of hydrophilic and hydrophobic units was varied in order to study the influence of hydrophobic block length on collapse pressure and area. The molecular weights of all polymers were around 15 kDa and 30 kDa. In the case of block copolymers we found a direct correlation of the length of the hydrophobic block to the collapse area. Furthermore, hysteresis experiments clearly point out that block copolymers form stable LB layers. No remarkable changes in collapse pressure or area could be observed. In contrast the area occupied by random copolymers changes at each hysteresis cycle indicating a loss of polymer to the aqueous subphase. In addition the LB layers were transferred onto mica substrates. The block copolymers formed stable and defect free membranes over an area of 100 microm(2) with a roughness (rms) 1.3-1.4 A. On the contrary, membranes based on random copolymers turned out to have a higher surface roughness. Our findings clearly underline the influence of polymer structure on the LB layer formation at the A/W interface.

Nanocarrier-Mediated Chemo-Immunotherapy Arrested Cancer Progression and Induced Tumor Dormancy in Desmoplastic Melanoma

“…As shown in the GPC assay, the nano-carrier (copolymer) with lower PDI helped in maintaining its stability and self-assembly properties, in similar to reports from other copolymer systems. 44, 45, 46, 47, 48 Importantly, the nano-carrier was unstable in either acidic or reductive conditions. Both are favorable properties for anti-cancer drug delivery.…”

P(HPMA)-block-P(LA) copolymers in paclitaxel formulations: Polylactide stereochemistry controls micellization, cellular uptake kinetics, intracellular localization and drug efficiency

“…The b Oregon Green (OG) content was determined by fluorimetry after purification. c Molecular weights were determined by GPC (THF with LiBr (c = 0.1 mmol/L)) or calculated from these measurements (see [67]). pH of the solutions was adjusted to 3.2, 5.2 and 7.2 in order to investigate acid-catalyzed hydrolysis of the block copolymers.…”

New Perspectives of HPMA‐based Copolymers Derived by Post‐Polymerization Modification

“…The self‐assembling behavior was also studied for designed HPMA lauryl methacrylate (LMA) copolymers (Figure ): For both statistical as well as block copolymers low critical micelle concentrations (cmc) could be observed . The amphiphilic copolymers form Langmuir‐Blodgett monolayers at the air‐water interface that could be transferred onto solid substrates . Moreover, due to their amphiphilic character they can be utilized as polymeric surfactants in miniemulsion polymerization or miniemulsion solvent evaporation technique affording polystyrene and polylactide colloids, respectively, with biocompatible HPMA coronas .…”

“…[50] The amphiphilic copolymers form Langmuir-Blodgett monolayers at the air-water interface that could be transferred onto solid substrates. [56] Moreover, due to their amphiphilic character they can be utilized as polymeric surfactants in miniemulsion polymerization or miniemulsion solvent evaporation technique affording polystyrene and polylactide colloids, respectively, with biocompatible HPMA coronas. [57] In aqueous solution statistical copolymers begin to self-assemble already with 10 mol% content of LMA at concentrations above cmc.…”