49 research outputs found
Nanofibers of Elastin and Hydrophilic Segmented Polyurethane Solution Blends Show Enhanced Mechanical Properties through Intermolecular Protein–Polymer H Bonding
Combining mechanical properties with
enhanced cell interaction
is highly desirable in a biomaterial. In this study, a new paradigm
for enhancing the mechanical properties of segmented polyurethanes
(SPUs) through solution blending with a biopolymer is presented. This
noncovalent approach is based on the premise that molecular level
blending of SPUs rich in hydrogen bonding (H bonding) domains with
a biopolymer capable of H bonding will promote H-bond bridges between
the components, leading to molecular annealing and modification of
the physicochemical properties of the SPU. We demonstrate that by
solution-blending solubilized elastin with a triblock copolymer-derived
SPU, a 5-fold increase in tensile modulus of electrospun constructs
of the SPU can be achieved, with concomitant enhancement in human
endothelial cell attachment. Spectroscopic and calorimetric analysis
confirm the role of H bonding in the enhancement, thus providing the
impetus to further explore blending with biopolymers as a means of
improving the property profiles of synthetic polymeric biomaterials
<i>In vivo</i> imaging and visualization of tumor mass and vasculature.
<p>(A) FT 3D reconstructed volumes of a rat bearing a MDA-E2 tumor (green) and the associated vasculature (red) visualized using AngioSense. Bar indicates 4.1 μm. (B) <i>Ex vivo</i> reflectance images of the corresponding tumor in (A). Bar indicates 4.1 μm. (C) Representative histological images of the tumor in (A) and (B) stained with antibodies against CD31 (red) and human nuclei (green). The nuclei were stained with DAPI (blue). The tumor mass is marked with (*) and the surrounding vascularized host stroma with (^). Bar indicates 100 μm.</p
<i>In vivo</i> detection of tumors in the lung.
<p>(A) Co-registration of FT and μCT data sets 36 days after tumor cell injection. Light gray indicates fluorescence signal detected by FT, skeletal structures were visualized by μCT and are colored red. (B) E<i>x vivo</i> reflectance image of the corresponding lung. (C) Representative histological image of the lung tissue with antibodies against CD31 (red) and human nuclei (green). The nuclei were stained with DAPI (blue). Clusters of human tumor cells are marked with (*).Bar indicates 100 μm.</p
Long-term detection of MDA-E2 cells <i>in vivo</i>.
<p>(A) MDA-E2 or MDA-WT tumor cells were injected in the flank of nude rats and the tumor size was measured using calipers. n = 5–6. (B) Rats bearing MDA-E2 tumors were scanned with FT. Left axis fluorescence intensity (black triangles) and right axis tumor volume (grey squares) measured using calipers. n = 6. All data is represented as mean ± standard deviation.</p
<i>In vitro</i> analysis of cell lines expressing E2-Crimson.
<p>The fluorescence intensity of various amounts of (A) MDA-E2, (B) HeLa-E2 and (C) A594-E2 cells, were measured in optical phantoms using FT. Non transduced parental cell lines (denoted with WT) were only measured at a concentration of 10<sup>6</sup> cells. (D-F) Cell viability and (G-I) migratory potential was compared between E2-Crimson expressing cells and the wild-type parental cell lines. All data is represented as mean ± standard deviation. Significance was measured by Students t test. n = 3.</p
Clickable Degradable Aliphatic Polyesters via Copolymerization with Alkyne Epoxy Esters: Synthesis and Postfunctionalization with Organic Dyes
Degradable aliphatic
polyesters are the cornerstones of nanoparticle
(NP)-based therapeutics. In this paradigm, covalent modification of
the NP with cell-targeting motifs and dyes can aid in guiding the
NP to its destination and gaining visual confirmation. Therefore,
strategies to impart chemistries along the polymer backbone that are
amenable to easy modification, such as 1,3-dipolar cycloaddition of
an azide to an alkyne (the “click reaction”), could
be significant. Here we present a simple and efficient way to introduce
alkyne groups at high density in aliphatic polyesters without compromising
their crystallinity via the copolymerization of cyclic lactones with
propargyl 3-methylpentenoate oxide (PMPO). Copolymers of lactic acid
and ε-caprolactone with PMPO were synthesized with up to 9 mol
% alkyne content, and accessibility of the alkyne groups to the click
reaction was demonstrated using several dyes commonly employed in
fluorescence microscopy and imaging (Cy3, ATTO-740, and coumarin 343).
In order to establish the suitability of these copolymers as nanocarriers,
copolymers were formulated into NPs, and cytocompatibility, cellular
uptake, and visualization studies undertaken in HeLa cells. Dye-modified
NPs exhibited no quenching, remained stable in solution for at least
10 days, showed no cytotoxicity, and were readily taken up by HeLa
cells. Furthermore, in addition to enabling the incorporation of multiple
fluorophores within the same NP through blending of individual dye-modified
copolymers, dye-modified polyesters offer advantages over physical
entrapment of dye, including improved signal to noise ratio and localization
of the fluorescence signal within cells, and possess the necessary
prerequisites for drug delivery and imaging
Overview of the key properties of poly(CL-<i>co</i>-OEG-MPO) copolymers.
<p>MPO: 2-methyl-4-pentenoate oxide; 1EG-MPO: 2-ethoxyethanol-MPO; 3EG-MPO: trimethylene glycol monomethyl ether-MPO; 12EG-MPO: poly(ethylene glycol) monomethyl ether-MPO.</p
Fluorescence images of MC3T3-E1 cells on poly(CL-<i>co</i>-OEG-MPO) copolymer films.
<p>Green: F-actin stress fibers; blue: nucleus. Note the change in cell morphology from a highly anisotropic cell morphology on unmodified PCL and low oligo-EG-PCL surfaces to a more isotropic (rounded) morphology on poly(CL-co-3EG-MPO) with 8% incorporation.</p
Static water contact angle of poly(CL-<i>co</i>-OEG-MPO) copolymers.
<p>Static water contact angle of poly(CL-<i>co</i>-OEG-MPO) copolymers.</p
Summary of the thermal properties of poly(CL-<i>co</i>-OEG-MPO) copolymers.
<p>MPO: 2-methyl-4-pentenoate oxide; 1EG-MPO: 2-ethoxyethanol-MPO; 3EG-MPO: trimethylene glycol monomethyl ether-MPO; 12EG-MPO: poly(ethylene glycol) monomethyl ether-MPO.</p