Study of the Air–Water Interfacial Properties of Biodegradable Polyesters and Their Block Copolymers with Poly(ethylene glycol)

Park, Hae-Woong; Choi, Je Yong; Ohn, Kimberly; Lee, Deokjung; Kim, Jinwoong; Won, You‐Yeon

doi:10.1021/la300810q

Cited by 24 publications

(96 citation statements)

References 45 publications

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“…30 We attribute, the hysteresis manifested upon film expansion to the viscoelastic behavior of polymer film. 30 Figure 2(c) shows that the intersection of linear extrapolation of steep Π- A region with the plateau region may yield the limiting surface area at which the aqueous area is just fully covered by polymers and Π starts to rise steeply. The isotherms of PI 2 DTEC differ significantly from those of PDTEC in some respects.…”

Section: Resultsmentioning

confidence: 92%

Structure of Biodegradable Films at Aqueous Surfaces: X-ray Diffraction and Spectroscopy Studies of Polylactides and Tyrosine-Derived Polycarbonates

et al. 2013

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Three representative polymers of increasing modulus, poly(D,L-lactic acid), PDLLA, poly(desaminotyrosyl-tyrosine ethyl ester carbonate), PDTEC, and the same polymer with iodinated DTE segments, PI2DTEC, were characterized by surface-pressure versus area (Π-A) isotherms and surface sensitive X-ray diffraction techniques. 10–100 Å thick films were prepared for these studies by spreading dilute polymer solutions at air-water interfaces. The general properties of the isotherms and the Flory exponents, determined from the isotherms, vary in accordance with the increasing modulus of PDLLA, PDTEC, PI2DTEC, respectively. The analysis of in-situ X-ray reflectivity and grazing incidence X-ray diffraction (GIXD) measurements from films at aqueous surfaces provides a morphological picture that is consistent with the modulus of the polymers, and to a large extent, with their packing in their dry-bulk state. Large absorption of X-rays by iodine enabled X-ray spectroscopic studies under near-total-reflection conditions to determine the iodine distribution in the PI2DTEC film and complement the structural model derived from reflectivity and GIXD. These structural studies lay the foundation for future studies of polymer-protein interactions at aqueous interfaces.

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Section: Resultsmentioning

confidence: 92%

Structure of Biodegradable Films at Aqueous Surfaces: X-ray Diffraction and Spectroscopy Studies of Polylactides and Tyrosine-Derived Polycarbonates

et al. 2013

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“…In a previous publication, 14 we speculated that the exponential rise in surface pressure observed at low film areas originates from the interconnected glassy PLGA domains that form within the polymer film under high compression. However, this understanding is incomplete; as will be demonstrated by the data presented in this subsection, the change in the PLGA structurewhatever it is -that causes the surface pressure upturn is produced only during compression (and as shown in Figure S4 that change is only short lived afterwards if the compression is stopped).…”

Section: Dynamic Nature Of the Surface Pressure Increase At High Compmentioning

confidence: 91%

“…4,14 From the results of these studies we concluded that Langmuir PLGA (Group II) films typically exhibit rapid increases in surface pressure under high compression because of a transformation of the material into a glassy state. This explanation was also supported by the observation that a Langmuir film formed by poly(D,L-lactic acid-ran-glycolic acid-ran-caprolactone) (PLGACL), which is similar in chemical structure to PLGA but is non-glassy due to the presence of the caprolactone co- Millipore-purified water (18 MΩ·cm resistivity) was used as the subphase.…”

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confidence: 99%

Humidity-dependent compression-induced glass transition of the air–water interfacial Langmuir films of poly(d,l-lactic acid-ran-glycolic acid) (PLGA)

et al. 2015

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Constant rate compression isotherms of the air-water interfacial Langmuir films of poly(D,L-lactic acid-ran-glycolic acid) (PLGA) show a distinct feature of an exponential increase in surface pressure in the high surface polymer concentration regime. We have previously demonstrated that this abrupt increase in surface pressure is linked to the glass transition of the polymer film, but the detailed mechanism of this process is not fully understood. In order to obtain a molecular-level understanding of this behavior, we performed extensive characterizations of the surface mechanical, structural and rheological properties of Langmuir PLGA films at the air-water interface, using combined experimental techniques including the Langmuir film balance, X-ray reflectivity and double-wall-ring interfacial rheometry methods. We observed that the mechanical and structural responses of the Langmuir PLGA films are significantly dependent on the rate of film compression; the glass transition was induced in the PLGA film only at fast compression rates. Surprisingly, we found that this deformation rate dependence is also dependent on the humidity of the environment. With water acting as a plasticizer for the PLGA material, the diffusion of water molecules through the PLGA film seems to be the key factor in the determination of the glass transformation properties and thus the mechanical response of the PLGA film against lateral compression. Based on our combined results, we hypothesize the following mechanism for the compression-induced glass transformation of the Langmuir PLGA film; (1) initially, a humidified/non-glassy PLGA film is formed in the full surface-coverage region (where the surface pressure shows a plateau) during compression; (2) further compression leads to the collapse of the PLGA chains and the formation of new surfaces on the air side of the film, and this newly formed top layer of the PLGA film is transiently glassy in character because the water evaporation rate in the top surface region is momentarily faster than the humidification rate (due to the initial roughness of the newly formed surface); (3) after some time, the top layer itself becomes humidified through diffusion of water from the subphase, and thus it becomes non-glassy, leading to the relaxation of the applied compressive stress.

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“…In the case of flat surfaces, the thickness of PEG layers has been determined with X-ray photoelectron spectroscopy (XPS), ellipsometry, 37 and atomic force microscopy (AFM). 80 Direct structural information about the 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 15 location of proteins has been obtained with reflectometric interference spectroscopy (RIfS) and neutron reflectometry. 81 The reflectrometry studies revealed that proteins can only penetrate into PEG layers of low grafting density.…”

mentioning

confidence: 99%

Surface Functionalization of Nanoparticles with Polyethylene Glycol: Effects on Protein Adsorption and Cellular Uptake

et al. 2015

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Here we have investigated the effect of enshrouding polymer-coated nanoparticles (NPs) with polyethylene glycol (PEG) on the adsorption of proteins and uptake by cultured cells. PEG was covalently linked to the polymer surface to the maximal grafting density achievable under our experimental conditions. Changes in the effective hydrodynamic radius of the NPs upon adsorption of human serum albumin (HSA) and fibrinogen (FIB) were measured in situ using fluorescence correlation spectroscopy. For NPs without a PEG shell, a thickness increase of around 3 nm, corresponding to HSA monolayer adsorption, was measured at high HSA concentration. Only 50% of this value was found for NPs with PEGylated surfaces. While the size increase clearly reveals formation of a protein corona also for PEGylated NPs, fluorescence lifetime measurements and quenching experiments suggest that the adsorbed HSA molecules are buried within the PEG shell. For FIB adsorption onto PEGylated NPs, even less change in NP diameter was observed. In vitro uptake of the NPs by 3T3 fibroblasts was reduced to around 10% upon PEGylation with PEG chains of 10 kDa. Thus, even though the PEG coatings did not completely prevent protein adsorption, the PEGylated NPs still displayed a pronounced reduction of cellular uptake with respect to bare NPs, which is to be expected if the adsorbed proteins are not exposed on the NP surface.

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Study of the Air–Water Interfacial Properties of Biodegradable Polyesters and Their Block Copolymers with Poly(ethylene glycol)

Cited by 24 publications

References 45 publications

Structure of Biodegradable Films at Aqueous Surfaces: X-ray Diffraction and Spectroscopy Studies of Polylactides and Tyrosine-Derived Polycarbonates

Structure of Biodegradable Films at Aqueous Surfaces: X-ray Diffraction and Spectroscopy Studies of Polylactides and Tyrosine-Derived Polycarbonates

Humidity-dependent compression-induced glass transition of the air–water interfacial Langmuir films of poly(d,l-lactic acid-ran-glycolic acid) (PLGA)

Surface Functionalization of Nanoparticles with Polyethylene Glycol: Effects on Protein Adsorption and Cellular Uptake

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