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Analysis of Silicon Quantum Dots and Serum Proteins Interactions Using Asymmetrical Flow Field-Flow Fractionation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023. [PMID: 37225422 DOI: 10.1021/acs.langmuir.3c00109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Semiconductor nanocrystals or quantum dots (QDs) have gained significant attention in biomedical research as versatile probes for imaging, sensing, and therapies. However, the interactions between proteins and QDs, which are crucial for their use in biological applications, are not yet fully understood. Asymmetric flow field-flow fractionation (AF4) is a promising method for analyzing the interactions of proteins with QDs. This technique uses a combination of hydrodynamic and centrifugal forces to separate and fractionate particles based on their size and shape. By coupling AF4 with other techniques, such as fluorescence spectroscopy and multi-angle light scattering, it is possible to determine the binding affinity and stoichiometry of protein-QD interactions. Herein, this approach has been utilized to determine the interaction between fetal bovine serum (FBS) and silicon quantum dots (SiQDs). Unlike metal-containing conventional QDs, SiQDs are highly biocompatible and photostable in nature, making them attractive for a wide range of biomedical applications. In this study, AF4 has provided crucial information on the size and shape of the FBS/SiQD complexes, their elution profile, and their interaction with serum components in real time. The differential scanning microcalorimetric technique has also been employed to monitor the thermodynamic behavior of proteins in the presence of SiQDs. We have investigated their binding mechanisms by incubating them at temperatures below and above the protein denaturation. This study yields various significant characteristics such as their hydrodynamic radius, size distribution, and conformational behavior. The compositions of SiQD and FBS influence the size distribution of their bioconjugates; the size increases by intensifying the concentration of FBS, with their hydrodynamic radii ranging between 150 and 300 nm. The results signify that in the alliance of SiQDs to the system, there is an augmentation of the denaturation point of the proteins and hence their thermal stability, providing a more comprehensive understanding of the interactions between FBS and QDs.
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Comparative Thermodynamic Studies of the Micellization of Amphiphilic Block Copolymers before and after Cyclization. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:5033-5039. [PMID: 35502540 DOI: 10.1021/acs.langmuir.0c03358] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The enthalpy and entropy of micellization in water, ΔHmic and ΔSmic, respectively, of three linear amphiphilic BAB block copolymers consisting of either poly(methyl acrylate) (Mn ∼ 1200 and 700 Da) or poly(ethyl acrylate) (Mn ∼ 800 Da) as hydrophobic (B) segments and poly(ethylene oxide) (PEO) as the hydrophilic (A, Mn ∼ 3000 Da) segment were determined by isothermal titration calorimetry (ITC). The ΔHmic and ΔSmic of the cyclic AB block copolymers obtained by cyclization of the linear triblock copolymers were determined under the same conditions. The ΔHmic value of the cyclic copolymers was smaller than that of their linear precursors. The ΔSmic value showed the same trend, but the relative difference between the cyclized and linear copolymers was less pronounced. The hydrodynamic diameter (Dh), critical micelle concentration (CMC), molecular weight (Mw-mic), and second virial coefficient (A2) of the micelles were determined. The Dh value of the cyclic copolymer micelles was smaller than the linear counterpart. On the other hand, the CMC value became larger, whereas the A2 value was comparable or increased by cyclization. Overall, the results suggest that, in the unimer state, the hydrophobic segments of the cyclized copolymers form a tightly coiled structure to minimize contact with water, resulting in the smaller ΔHmic value. Contrary to the linear copolymer micelles, the cyclic copolymer micelles have no "dangling chains", which may explain the topology-driven slight difference in the ΔSmic value.
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Synthesis of New Thermoresponsive Polymers Possessing the Dense 1,2,3-Triazole Backbone. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:5156-5165. [PMID: 34797074 DOI: 10.1021/acs.langmuir.1c02266] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Thermoresponsive water-soluble polymers, aqueous solutions of which undergo lower critical solution temperature (LCST)-type phase separation, have been investigated in detail for several decades. To develop LCST-type thermoresponsive polymers with new polymer backbone, 4-azido-5-hexynamide (AHA) derivatives were designed as monomers for copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) polymerization. AHA derivatives carrying secondary amide side chains, that is, 4-azido-N-methyl-5-hexynamide (M), 4-azido-N-ethyl-5-hexynamide (E), and 4-azido-N-isopropyl-5-hexynamide (iP), were first synthesized and polymerized by CuAAC to obtain polymers (poly(M), poly(E), and poly(iP)). Contrary to our expectation, poly(M), poly(E), and poly(iP) were insoluble in water and many organic solvents presumably because of the formation of hydrogen bonding between the amide side chains or between the amide side chains and triazole residues in the backbone. Thus, AHA derivatives carrying tertiary amide side chains, that is, 4-azido-N,N-dimethyl-5-hexynamide (MM), 4-azido-N-ethyl-N-methyl-5-hexynamide (ME), 4-azido-N-isopropyl-N-methyl-5-hexynamide (MiP), and 4-azido-N,N-diethyl-5-hexynamide (EE), were also synthesized and polymerized to yield polymers (poly(MM), poly(ME), poly(MiP), and poly(EE)). These polymers were soluble in a number of common organic solvents. It is noteworthy that poly(MM) and poly(ME) were also soluble in water. The phase separation behavior of 1.0 wt % aqueous solutions of poly(MM) and poly(ME) was then investigated by transmittance measurements. These data indicated that poly(ME) was an LCST-type thermoresponsive polymer, whereas poly(MM) was not. A large hysteresis was observed in the transmittance measurements for the poly(ME) aqueous solution because of slow rehydration after phase separation. The phase separation behavior was investigated preliminarily by differential scanning calorimetry and 1H NMR.
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Heat-Induced Flower Nanogels of Both Cholesterol End-Capped Poly( N-isopropylacrylamide)s in Water. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:5218-5225. [PMID: 34730981 DOI: 10.1021/acs.langmuir.1c02394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Thermoresponsive self-assembled nanogels were conveniently prepared by cholesterol end-capped poly(N-isopropylacrylamide) (PNIPAM) in water. Both cholesterol end-capped PNIPAMs (telelchelic cholesterol PNIPAM, tCH-PNIPAM) formed flower-like nanogels by the self-assembling of four to five polymer chains with multiple domains of cholesterol in water at 20 °C. Meanwhile, one end-group cholesterol-capped PNIPAM (semitelechelic cholesterol PNIPAM, stCH-PNIPAM) was also formed as a nanogel by the self-assembling of 15-20 polymer chains with 3 to 4 cholesterol domains. The hydrophobic cholesterol domains of tCH-PNIPAM nanogels were maintained above the lower critical solution temperature (LCST) of PNIPAM (>32 °C). Differently, the hydrophobic domains of stCH-PNIPAM were disrupted by cholesterol-free PNIPAM chain ends and formed large mesoglobules above the LCST. These transition controls of hydrophilic end-capped smart polymers may open new methodologies to design thermoresponsive nanosystems.
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Probing interfacial interactions and dynamics of polymers enclosed in boron nitride nanotubes. JOURNAL OF POLYMER SCIENCE 2021. [DOI: 10.1002/pol.20210620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Enthalpy of the Complexation in Electrolyte Solutions of Polycations and Polyzwitterions of Different Structures and Topologies. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c00586] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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High-Sensitivity Microcalorimetry and Gel Permeation Chromatography in Tandem Reveal the Complexity of the Synthesis of Poly-(2-isopropyl-2-oxazoline) Stars. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c00746] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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The Two Phase Transitions of Hydrophobically End-Capped Poly( N-isopropylacrylamide)s in Water. Macromolecules 2020; 53:5105-5115. [PMID: 32952216 PMCID: PMC7497654 DOI: 10.1021/acs.macromol.0c00487] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Revised: 05/25/2020] [Indexed: 01/03/2023]
Abstract
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High-sensitivity
differential scanning calorimetry (HS-DSC) thermograms of aqueous
poly(N-isopropylacrylamide) (PNIPAM) solutions present
a sharp unimodal endotherm that signals the heat-induced dehydration/collapse
of the PNIPAM chain. Similarly, α,ω-di-n-octadecyl-PNIPAM (C18-PN-C18) aqueous solutions exhibit a unimodal
endotherm. In contrast, aqueous solutions of α,ω-hydrophobically
modified PNIPAMs with polycyclic terminal groups, such as pyrenylbutyl
(Py-PN-Py), adamantylethyl (Ad-PN-Ad), and azopyridine- (C12-PN-AzPy)
moieties, exhibit bimodal thermograms. The origin of the two transitions
was probed using microcalorimetry measurements, turbidity tests, variable
temperature 1H NMR (VT-NMR) spectroscopy, and 2-dimensional
NOESY experiments with solutions of polymers of molar mass (Mn) from 5 to 20 kDa and polymer concentrations
of 0.1 to 3.0 mg/mL. The analysis outcome led us to conclude that
the difference of the thermograms reflects the distinct self-assembly
structures of the polymers. C18-PN-C18 assembles in water in the form
of flower micelles held together by a core of tightly packed n-C18 chains. In contrast, polymers end-tagged with azopyridine,
pyrenylbutyl, or adamantylethyl form a loose core that allows chain
ends to escape from the micelles, to reinsert in them, or to dangle
in surrounding water. The predominant low temperature (T1) endotherm, which is insensitive to polymer concentration,
corresponds to the dehydration/collapse of PNIPAM chains within the
micelles, while the higher temperature (T2) endotherm is attributed to the dehydration of dangling chains and
intermicellar bridges. This study of the two phase transitions of
telechelic PNIPAM homopolymer highlights the rich variety of morphologies
attainable via responsive hydrophobically modified aqueous polymers
and may open the way to a variety of practical applications.
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Azopyridine: a smart photo- and chemo-responsive substituent for polymers and supramolecular assemblies. Polym Chem 2020. [DOI: 10.1039/d0py01093f] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
This mini-review summarizes key features of the photoisomerization of polymer-tethered azopyridine in aqueous media and describes recent accomplishments on the fast thermal cis-to-trans relaxation of azopyridinium or H-bonded azopyridine.
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December 2019. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:16969. [PMID: 31888340 DOI: 10.1021/acs.langmuir.9b03841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
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Phototropic Multiresponsive Active Nanogels. Macromol Rapid Commun 2019; 40:e1900479. [DOI: 10.1002/marc.201900479] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 10/11/2019] [Indexed: 12/16/2022]
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Poly(2-propyl-2-oxazoline)s in Aqueous Methanol: To Dissolve or not to Dissolve. Macromolecules 2019; 52:6361-6368. [PMID: 31543552 PMCID: PMC6748674 DOI: 10.1021/acs.macromol.9b01234] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 08/01/2019] [Indexed: 11/30/2022]
Abstract
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At
room temperature, poly(N-isopropylacrylamide)
(PNIPAM) is soluble in water and methanol, but it is not soluble in
certain water/methanol mixtures. This phenomenon, known as cononsolvency,
has been explored in great detail experimentally and theoretically
in an attempt to understand the complex interactions occurring in
the ternary PNIPAM/water/co-nonsolvent system. Yet little is known
about the effects of the polymer structure on cononsolvency. To address
this point, we investigated the temperature-dependent solution properties
in water, methanol, and mixtures of the two solvents of poly(2-cyclopropyl-2-oxazoline)
(PcyPOx) and two structural isomers of PNIPAM (Mn ∼ 11 kg/mol): poly(2-isopropyl-2-oxazoline) (PiPOx)
and poly(2-n-propyl-2-oxazoline) (PnPOx). The phase
diagram of the ternary water/methanol/poly(2-propyl-2-oxazolines)
(PPOx) systems, constructed based on cloud point (TCP) measurements, revealed that PnPOx exhibits cononsolvency
in water/methanol mixtures. In contrast, methanol acts as a cosolvent
for PiPOx and PcyPOx in water. The enthalpy, ΔH, and temperature, Tmax, of the coil-to-globule
transition of the three polymers in various water/methanol mixtures
were measured by high-sensitivity differential scanning calorimetry. Tmax follows the same trends as TCP, confirming the cononsolvency of PnPOx and the cosolvency
of PiPOx and PcyPOx. ΔH decreases linearly
as a function of the methanol content for all PPOx systems. Ancillary
high-resolution 1H NMR spectroscopy studies of PPOx solutions
in D2O and methanol-d4, coupled
with DOSY and NOESY experiments revealed that the n-propyl group of PnPOx rotates freely in D2O, whereas
the rotation of the isopropyl and cyclopropyl groups of PiPOx and
PcyPOx, respectively, is limited due to steric restriction. This factor
appears to play an important role in the case of the PPOxs/water/methanol
ternary system.
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Polymeric Nanoparticles Limit the Collective Migration of Cellular Aggregates. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:7396-7404. [PMID: 29975543 PMCID: PMC6562752 DOI: 10.1021/acs.langmuir.8b01736] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 07/04/2018] [Indexed: 05/23/2023]
Abstract
Controlling the propagation of primary tumors is fundamental to avoiding the epithelial to mesenchymal transition process leading to the dissemination and seeding of tumor cells throughout the body. Here we demonstrate that nanoparticles (NPs) limit the propagation of cell aggregates of CT26 murine carcinoma cells used as tumor models. The spreading behavior of these aggregates incubated with NPs is studied on fibronectin-coated substrates. The cells spread with the formation of a cell monolayer, the precursor film, around the aggregate. We study the effect of NPs added either during or after the formation of aggregates. We demonstrate that, in both cases, the spreading of the cell monolayer is slowed down in the presence of NPs and occurs only above a threshold concentration that depends on the size and surface chemistry of the NPs. The density of cells in the precursor films, measured by confocal microscopy, shows that the NPs stick cells together. The mechanism of slowdown is explained by the increase in cell-cell interactions due to the NPs adsorbed on the membrane of the cells. The present results demonstrate that NPs can modulate the collective migration of cells; therefore, they may have important implications for cancer treatment.
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Preface to The 15th Pacific Polymer Conference (PPC-15) Virtual Issue. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:4413-4414. [PMID: 30811207 DOI: 10.1021/acs.langmuir.9b00560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
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pH-Dependent Morphology and Photoresponse of Azopyridine-Terminated Poly( N-isopropylacrylamide) Nanoparticles in Water. Macromolecules 2019; 52:2939-2948. [PMID: 31496545 PMCID: PMC6727601 DOI: 10.1021/acs.macromol.9b00193] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Revised: 03/17/2019] [Indexed: 01/01/2023]
Abstract
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A series of azopyridine-terminated
poly(N-isopropylacrylamide)s
(PNIPAM) (C12-PN-AzPy) (∼5000 < Mw < 20 000 g mol–1, polydispersity index
1.25 or less) were prepared by reversible addition–fragmentation
chain-transfer polymerization of NIPAM in the presence of a chain-transfer
agent that contains an AzPy group and an n-dodecyl
chain. In cold water, the polymers form nanoparticles (5.9 nm < Rh < 10.9 nm) that were characterized by light
scattering (LS), 1H NMR diffusion experiments, and high-resolution
transmission electron microscopy. We monitored the pH-dependent photoisomerization
of C12-PN-AzPy nanoparticles by steady-state and time-resolved UV–vis
absorption spectroscopy. Azopyridine is known to undergo a very fast
cis-to-trans thermal relaxation when the azopyridine nitrogen is quaternized
or bound to a hydrogen bond donor. The cis-to-trans thermal relaxation
of the AzPy chromophore in an acidic nanoparticle suspension is very
fast with a half-life τ = 2.3 ms at pH 3.0. It slows down slightly
for nanoparticles in neutral water (τ = 0.96 s, pH 7.0), and
it is very slow for AzPy-PNIPAM particles in alkaline medium (τ
> 3600 s, pH 10). The pH-dependent dynamics of the cis-to-trans
dark
relaxation, supported by Fourier transform infrared spectroscopy, 1H NMR spectroscopy, and LS analysis, suggest that in acidic
medium, the nanoparticles consist of a core of assembled C12 chains
surrounded by a shell of hydrated PNIPAM chains with the AzPy+ end groups preferentially located near the particle/water
interface. In neutral medium, the shell surrounding the core contains
AzPy groups H-bonded to the amide hydrogen of the PNIPAM chain repeat
units. At pH 10.0, the amide hydrogen binds preferentially to the
hydroxide anions. The AzPy groups reside preferentially in the vicinity
of the C12 core of the nanoparticles. The morphology of the nanoparticles
results from the competition between the segregation of the hydrophobic
and hydrophilic components and weak attractive interactions, such
as H-bonds between the AzPy groups and the amide hydrogen of the PNIPAM
repeat units.
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Poly(2-isopropyl-2-oxazoline)- b-poly(lactide) (PiPOx- b-PLA) Nanoparticles in Water: Interblock van der Waals Attraction Opposes Amphiphilic Phase Separation. Macromolecules 2019; 52:1317-1326. [PMID: 31496543 PMCID: PMC6727592 DOI: 10.1021/acs.macromol.8b02558] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 01/16/2019] [Indexed: 12/17/2022]
Abstract
Poly(2-isopropyl-2-oxazoline)-b-poly(lactide) (PiPOx-b-PLA) diblock copolymers comprise two miscible blocks: the hydrophilic and thermosensitive PiPOx and the hydrophobic PLA, a biocompatible and biodegradable polyester. They self-assemble in water, forming stable dispersions of nanoparticles with hydrodynamic radii (R h) ranging from ∼18 to 60 nm, depending on their molar mass, the relative size of the two blocks, and the configuration of the lactide unit. Evidence from 1H nuclear magnetic resonance spectroscopy, light scattering, small-angle neutron scattering, and cryo-transmission electron microscopy indicates that the nanoparticles do not adopt the typical core-shell morphology. Aqueous nanoparticle dispersions heated from 20 to 80 °C were monitored by turbidimetry and microcalorimetry. Nanoparticles of copolymers containing a poly(dl-lactide) block coagulated irreversibly upon heating to 50 °C, forming particles of various shapes (R h ∼ 200-500 nm). Dispersions of PiPOx-b-poly(l-lactide) coagulated to a lesser extent or remained stable upon heating. From the entire experimental evidence, we conclude that PiPOx-b-PLA nanoparticles consist of a core of PLA/PiPOx chains associated via dipole-dipole interactions of the PLA and PiPOx carbonyl groups. The core is surrounded by tethered PiPOx loops and tails responsible for the colloidal stability of the nanoparticles in water. While the core of all nanoparticles studied contains associated PiPOx and PLA blocks, fine details of the nanoparticles morphology vary predictably with the size and composition of the copolymers, yielding particles of distinctive thermosensitivity in aqueous dispersions.
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Spreading of Cell Aggregates on Zwitterion-Modified Chitosan Films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:1902-1908. [PMID: 30142974 PMCID: PMC6365911 DOI: 10.1021/acs.langmuir.8b02461] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 08/16/2018] [Indexed: 06/08/2023]
Abstract
The sulfobetaine (SB) moiety, which comprises a quaternary ammonium group linked to a negatively charged sulfonate ester, is known to impart nonfouling properties to interfaces coated with polysulfobetaines or grafted with SB-polymeric brushes. Increasingly, evidence emerges that the SB group is, overall, a better antifouling group than the phosphorylcholine (PC) moiety extensively used in the past. We report here the synthesis of a series of SB-modified chitosans (CH-SB) carrying between 20 and 40 mol % SB per monosaccharide unit. Chitosan (CH) itself is a naturally derived copolymer of glucosamine and N-acetyl-glucosamine linked with a β-1,4 bond. Analysis by quartz crystal microbalance with dissipation (QCM-D) indicates that CH-SB films (thickness ∼ 20 nm) resist adsorption of bovine serum albumin (BSA) with increasing efficiency as the SB content of the polymer augments (surface coverage ∼ 15 μg cm-2 for films of CH with 40 mol % SB). The cell adhesivity of CH-SB films coated on glass was assessed by determining the spreading dynamics of CT26 cell aggregates. When placed on chitosan films, known to be cell-adhesive, the CT26 cell aggregates spread by forming a cell monolayer around them. The spreading of CT26 cell aggregates on zwitterion-modified chitosans films is thwarted remarkably. In the cases of CH-SB30 and CH-SB40 films, only a few isolated cells escape from the aggregates. The extent of aggregate spreading, quantified based on the theory of liquid wetting, provides a simple in vitro assay of the nonfouling properties of substrates toward specific cell lines. This assay can be adopted to test and compare the fouling characteristics of substrates very different from the chemical viewpoint.
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Thermoresponsive Pentablock Copolymer on Silica: Temperature Effects on Adsorption, Surface Forces, and Friction. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:653-661. [PMID: 30605339 DOI: 10.1021/acs.langmuir.8b03729] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The adsorption of hydrophilic or amphiphilic multiblock copolymers provides a powerful means to produce well-defined "smart" surfaces, especially if one or several blocks are sensitive to external stimuli. We focus here on an A-B-A-B-A copolymer, where A is a cationic poly((3-acrylamido-propyl)-trimethylammonium chloride) (PAMPTMA) block containing 15 (end blocks) or 30 (middle block) repeat units and B is a neutral thermosensitive water-soluble poly(2-isopropyl-2-oxazoline) (PIPOZ) block with 50 repeat units. X-ray reflectivity and quartz crystal microbalance with dissipation monitoring were employed to study the adsorption of PAMPTMA15-PIPOZ50-PAMPTMA30-PIPOZ50-PAMPTMA15 on silica surfaces. The latter technique was employed at different temperatures up to 50 °C. Surface forces and friction between the two silica surfaces across aqueous pentablock copolymer solutions at different temperatures were determined with the atomic force microscopy colloidal probe force and friction measurements. The cationic pentablock copolymer was found to have a high affinity to the negatively charged silica surface, leading to a thin (2 nm) and rigid adsorbed layer. A steric force was encountered at a separation of around 3 nm from hard wall contact. A capillary condensation of a polymer-rich phase was observed at the cloud point of the solution. The friction forces were evaluated using Amontons' rule modified with an adhesion term.
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Dehydration, Micellization, and Phase Separation of Thermosensitive Polyoxazoline Star Block Copolymers in Aqueous Solution. Macromolecules 2019. [DOI: 10.1021/acs.macromol.8b02528] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Light, temperature, and pH control of aqueous azopyridine-terminated poly(N-isopropylacrylamide) solutions. Polym Chem 2019. [DOI: 10.1039/c9py01086f] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Azopyridines (AzPy) act as light-sensitive groups that undergo reversible cis–trans isomerization upon UV irradiation, as hydrogen-bond acceptors, and as ionizable moieties.
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Temperature-Controlled Interactions between Poly(N-isopropylacrylamide) Mesoglobules Probed by Fluorescence. Macromolecules 2018. [DOI: 10.1021/acs.macromol.8b00003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Fast and effective mitochondrial delivery of ω-Rhodamine-B-polysulfobetaine-PEG copolymers. Sci Rep 2018; 8:1128. [PMID: 29348616 PMCID: PMC5773493 DOI: 10.1038/s41598-018-19598-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 01/04/2018] [Indexed: 01/08/2023] Open
Abstract
Mitochondrial targeting and entry, two crucial steps in fighting severe diseases resulting from mitochondria dysfunction, pose important challenges in current nanomedicine. Cell-penetrating peptides or targeting groups, such as Rhodamine-B (Rho), are known to localize in mitochondria, but little is known on how to enhance their effectiveness through structural properties of polymeric carriers. To address this issue, we prepared 8 copolymers of 3-dimethyl(methacryloyloxyethyl)ammonium propane sulfonate and poly(ethyleneglycol) methacrylate, p(DMAPS-ran-PEGMA) (molecular weight, 18.0 < M n < 74.0 kg/mol) with two different endgroups. We labeled them with Rho groups attached along the chain or on one of the two endgroups (α or ω). From studies by flow cytometry and confocal fluorescence microscopy of the copolymers internalization in HeLa cells in the absence and presence of pharmacological inhibitors, we established that the polymers cross the cell membrane foremost by translocation and also by endocytosis, primarily clathrin-dependent endocytosis. The most effective mitochondrial entry was achieved by copolymers of M n < 30.0 kg/mol, lightly grafted with PEG chains (< 5 mol %) labeled with Rho in the ω-position. Our findings may be generalized to the uptake and mitochondrial targeting of prodrugs and imaging agents with a similar polymeric scaffold.
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Inversion of crystallization rates in miscible block copolymers of poly(lactide)- block-poly(2-isopropyl-2-oxazoline). Polym Chem 2018. [DOI: 10.1039/c8py00198g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
From a miscible melt, crystallization drives phase-separation of PLLA-PiPOx. PLLA plasticizes PiPOx and inverts the crystallization rates compared to the homopolymers.
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25
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How gluttonous cell aggregates clear substrates coated with microparticles. Sci Rep 2017; 7:15729. [PMID: 29146990 PMCID: PMC5691206 DOI: 10.1038/s41598-017-15665-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 10/27/2017] [Indexed: 11/09/2022] Open
Abstract
We study the spreading of cell aggregates deposited on adhesive substrates decorated with microparticles (MPs). A cell monolayer expands around the aggregate. The cells on the periphery of the monolayer take up the MPs, clearing the substrate as they progress and forming an aureole of cells filled with MPs. We study the dynamics of spreading and determine the width of the aureole and the level of MP internalization in cells as a function of MP size, composition, and density. From the radius and width of the aureole, we quantify the volume fraction of MPs within the cell, which leads to an easy, fast, and inexpensive measurement of the cell - particle internalization.
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Temperature response of aqueous solutions of pyrene end-labeled poly(N
-isopropylacrylamide)s probed by steady-state and time-resolved fluorescence. ACTA ACUST UNITED AC 2017. [DOI: 10.1002/polb.24543] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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27
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Stability and binding affinity of DNA/chitosan complexes by polyanion competition. Carbohydr Polym 2017; 176:167-176. [DOI: 10.1016/j.carbpol.2017.08.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 05/24/2017] [Accepted: 08/01/2017] [Indexed: 12/20/2022]
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28
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Polysulfobetaine-surfactant solutions and their use in stabilizing hydrophobic compounds in saline solution. POLYMER 2017. [DOI: 10.1016/j.polymer.2017.08.057] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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29
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Nonequilibrium Liquid–Liquid Phase Separation of Poly(N-isopropylacrylamide) in Water/Methanol Mixtures. Macromolecules 2017. [DOI: 10.1021/acs.macromol.7b00407] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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30
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Abstract
Impurity-doping in nanocrystals significantly affects their electronic properties and diversifies their applications. Herein, we report the synthesis of transition metal (Mn, Ni, Co, Cu)-doped oleophilic silicon nanocrystals (SiNCs) through hydrolysis/polymerization of triethoxysilane with acidic aqueous metal salt solutions, followed by thermal disproportionation of the resulting gel into a doped-Si/SiO2 composite that, upon HF etching and hydrosilylation with 1-n-octadecene, produces free-standing octadecyl-capped doped SiNCs (diameter≈3 to 8 nm; dopant <0.2 atom %). Metal-doping triggers a red-shift of the SiNC photoluminescence (PL) of up to 270 nm, while maintaining high PL quantum yield (26 % for Co doping).
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31
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Transition‐Metal‐Doped NIR‐Emitting Silicon Nanocrystals. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201700436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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32
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Macromol. Biosci. 2/2017. Macromol Biosci 2017. [DOI: 10.1002/mabi.201770009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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33
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Small-angle X-ray scattering from the concentrated bulk phase separated from an amphiphilic block-copolymer solution. Polym J 2017. [DOI: 10.1038/pj.2016.124] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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34
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Editorial. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:1. [PMID: 28068778 DOI: 10.1021/acs.langmuir.6b04616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
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35
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A one-pot synthesis of water soluble highly fluorescent silica nanoparticles. J Mater Chem B 2017; 5:1363-1370. [DOI: 10.1039/c6tb02813f] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We report a one-pot synthesis of water dispersible fluorescent silica nanoparticles (NPs) functionalized with terminal amine groups, starting from silicon tetrabromide (SiBr4) and aminopropyltriethoxy silane (APTES).
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36
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Preface to the Nanobubbles Special Issue. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:11071. [PMID: 27798962 DOI: 10.1021/acs.langmuir.6b03429] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
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37
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Nanostickers for cells: a model study using cell-nanoparticle hybrid aggregates. SOFT MATTER 2016; 12:7902-7907. [PMID: 27714338 DOI: 10.1039/c6sm01450j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We present direct evidence that nanoparticles (NPs) can stick together cells that are inherently non-adhesive. Using cadherin-depleted S180 murine cells lines, which exhibit very low cell-cell adhesion, we show that NPs can assemble dispersed single cells into large cohesive aggregates. The dynamics of aggregation, which is controlled by diffusion and collision, can be described as a second-order kinetic law characterized by a rate of collision that depends on the size, concentration, and surface chemistry of the NPs. We model the cell-cell adhesion induced by the "nanostickers" using a three-state dynamical model, where the NPs are free, adsorbed on the cell membrane or internalized by the cells. We define a "sticking efficiency parameter" to compare NPs and look for the most efficient type of NP. We find that 20 nm carboxylated polystyrene NPs are more efficient nanostickers than 20 nm silica NPs which were reported to induce fast wound healing and to glue soft tissues. Nanostickers, by increasing the cohesion of tissues and tumors, may have important applications for tissue engineering and cancer treatment.
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Refolding of Aggregation-Prone ScFv Antibody Fragments Assisted by Hydrophobically Modified Poly(sodium acrylate) Derivatives. Macromol Biosci 2016; 17. [DOI: 10.1002/mabi.201600213] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 07/19/2016] [Indexed: 11/06/2022]
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39
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Estradiol-tethered micropatterned surfaces for the study of estrogenic non-genomic pathways. Chem Commun (Camb) 2016; 52:10056-9. [PMID: 27451960 DOI: 10.1039/c6cc03899a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Besides its well-known hormonal effects initiated in the nucleus, estradiol (E2) also activates non-nuclear pathways through interactions with receptors located on the cell plasma membrane. Micropatterned substrates consisting of gold dots bearing tethered E2 distributed on a cell-adhesive substrate were prepared and shown to trigger specifically E2 non-genomic effects in cells grown on the substrates.
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40
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Effect of chain architecture on the phase transition of star and cyclic poly(N-isopropylacrylamide) in water. ACTA ACUST UNITED AC 2016. [DOI: 10.1002/polb.24114] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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41
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Functional double-shelled silicon nanocrystals for two-photon fluorescence cell imaging: spectral evolution and tuning. NANOSCALE 2016; 8:9009-19. [PMID: 27076260 DOI: 10.1039/c6nr01437b] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Functional near-IR (NIR) emitting nanoparticles (NPs) adapted for two-photon excitation fluorescence cell imaging were obtained starting from octadecyl-terminated silicon nanocrystals (ncSi-OD) of narrow photoluminescence (PL) spectra having no long emission tails, continuously tunable over the 700-1000 nm window, PL quantum yields exceeding 30%, and PL lifetimes of 300 μs or longer. These NPs, consisting of a Pluronic F127 shell and a core made up of assembled ncSi-OD kept apart by an octadecyl (OD) layer, were readily internalized into the cytosol, but not the nucleus, of NIH3T3 cells and were non-toxic. Asymmetrical field-flow fractionation (AF4) analysis was carried out to determine the size of the NPs in water. HiLyte Fluor 750 amine was linked via an amide link to NPs prepared with Pluronic-F127-COOH, as a first demonstration of functional NIR-emitting water dispersible ncSi-based nanoparticles.
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42
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Membrane Translocation and Organelle-Selective Delivery Steered by Polymeric Zwitterionic Nanospheres. Biomacromolecules 2016; 17:1523-35. [DOI: 10.1021/acs.biomac.6b00172] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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43
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Boron nitride nanotubes as vehicles for intracellular delivery of fluorescent drugs and probes. Nanomedicine (Lond) 2016; 11:447-63. [PMID: 26891593 DOI: 10.2217/nnm.15.214] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
AIM To evaluate the response of cells to boron nitride nanotubes (BNNTs) carrying fluorescent probes or drugs in their inner channel by assessment of the cellular localization of the fluorescent cargo, evaluation of the in vitro release and biological activity of a drug (curcumin) loaded in BNNTs. METHODS Cells treated with curcumin-loaded BNNTs and stimulated with lipopolysaccharide were assessed for nitric oxide release and stimulation of IL-6 and TNF-α. The cellular trafficking of two cell-permeant dyes and a non-cell-permeant dye loaded within BNNTs was imaged. RESULTS BNNTs loaded with up to 13 wt% fluorophores were internalized by cells and controlled release of curcumin triggered cellular pathways associated with the known anti-inflammatory effects of the drug. CONCLUSION The overall findings indicate that BNNTs can function as nanocarriers of biologically relevant probes/drugs allowing one to examine/control their local intracellular localization and biochemical effects, leading the way to applications as intracellular nanosensors.
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Our Vision for a Bright Future. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:1. [PMID: 26717027 DOI: 10.1021/acs.langmuir.5b04453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
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45
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Influence of Confinement on the Chain Conformation of Cyclic Poly( N-isopropylacrylamide). ACS Macro Lett 2015; 4:1362-1365. [PMID: 35614783 DOI: 10.1021/acsmacrolett.5b00676] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In thin and ultrathin supported films, the conformations of flexible linear polymer chains might be considerably confined, in particular, for film thicknesses smaller than a few times the radius of gyration. For ring polymers in solution or in melt, the radii of gyration are significantly reduced as compared to those of their linear counterparts. We study here the influence of geometrical confinement on the chain conformation of cyclic PNIPAM in silicon-supported films. Measurements are performed by grazing incidence small angle neutron scattering (GISANS). For all films, the component of the radius of gyration parallel to the substrate, Rgc∥, is significantly higher than the unperturbed Rgc determined under theta solvent or melt conditions. We attribute this effect to a preferential selection of stretched PNIPAM ring conformations in thin films and a preferential orientation of macromolecules parallel to the film interfaces with the substrate and air.
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46
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Formation of Tethers from Spreading Cellular Aggregates. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:12984-12992. [PMID: 26509898 DOI: 10.1021/acs.langmuir.5b02785] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Membrane tubes are commonly extruded from cells and vesicles when a point-like force is applied on the membrane. We report here the unexpected formation of membrane tubes from lymph node cancer prostate (LNCaP) cell aggregates in the absence of external applied forces. The spreading of LNCaP aggregates deposited on adhesive glass substrates coated with fibronectin is very limited because cell-cell adhesion is stronger than cell-substrate adhesion. Some cells on the aggregate periphery are very motile and try to escape from the aggregate, leading to the formation of membrane tubes. Tethered networks and exchange of cargos between cells were observed as well. Growth of the tubes is followed by either tube retraction or tube rupture. Hence, even very cohesive cells are successful in escaping aggregates, which may lead to epithelial mesenchymal transition and tumor metastasis. We interpret the dynamics of formation and retraction of tubes in the framework of membrane mechanics.
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Poly(N-isopropylacrylamide) Phase Diagrams: Fifty Years of Research. Angew Chem Int Ed Engl 2015; 54:15342-67. [PMID: 26612195 DOI: 10.1002/anie.201506663] [Citation(s) in RCA: 574] [Impact Index Per Article: 63.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Indexed: 11/10/2022]
Abstract
In 1968, Heskins and Guillet published the first systematic study of the phase diagram of poly(N-isopropylacrylamide) (PNIPAM), at the time a "young polymer" first synthesized in 1956. Since then, PNIPAM became the leading member of the growing families of thermoresponsive polymers and of stimuli-responsive, "smart" polymers in general. Its thermal response is unanimously attributed to its phase behavior. Yet, in spite of 50 years of research, a coherent quantitative picture remains elusive. In this Review we survey the reported phase diagrams, discuss the differences and comment on theoretical ideas regarding their possible origins. We aim to alert the PNIPAM community to open questions in this reputably mature domain.
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Cell-specific optoporation with near-infrared ultrafast laser and functionalized gold nanoparticles. NANOSCALE 2015; 7:17836-47. [PMID: 26459958 DOI: 10.1039/c5nr05650k] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Selective targeting of diseased cells can increase therapeutic efficacy and limit off-target adverse effects. We developed a new tool to selectively perforate living cells with functionalized gold nanoparticles (AuNPs) and near-infrared (NIR) femtosecond (fs) laser. The receptor CD44 strongly expressed by cancer stem cells was used as a model for selective targeting. Citrate-capped AuNPs (100 nm in diameter) functionalized with 0.01 orthopyridyl-disulfide-poly(ethylene glycol) (5 kDa)-N-hydroxysuccinimide (OPSS-PEG-NHS) conjugated to monoclonal antibodies per nm(2) and 5 μM HS-PEG (5 kDa) were colloidally stable in cell culture medium containing serum proteins. These AuNPs attached mostly as single particles 115 times more to targeted CD44(+) MDA-MB-231 and CD44(+) ARPE-19 cells than to non-targeted CD44(-) 661W cells. Optimally functionalized AuNPs enhanced the fs laser (800 nm, 80-100 mJ cm(-2) at 250 Hz or 60-80 mJ cm(-2) at 500 Hz) to selectively perforate targeted cells without affecting surrounding non-targeted cells in co-culture. This novel highly versatile treatment paradigm can be adapted to target and perforate other cell populations by adapting to desired biomarkers. Since living biological tissues absorb energy very weakly in the NIR range, the developed non-invasive tool may provide a safe, cost-effective clinically relevant approach to ablate pathologically deregulated cells and limit complications associated with surgical interventions.
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Temperature sensitive supramolecular self assembly of per-6-PEO-β-cyclodextrin and α,ω-di-(adamantylethyl)poly(N-isopropylacrylamide) in water. SOFT MATTER 2015; 11:6432-6443. [PMID: 26179328 DOI: 10.1039/c5sm01293g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The host/guest interactions in water of a star polymer consisting of a β-cyclodextrin (β-CD) core bearing six poly(ethylene oxide) arms linked to the C6 positions of β-CD (β-CD-PEO7, Mn 5000 g mol(-1)) and α,ω-di-(adamantylethyl)poly(N-isopropylacrylamide) (Ad-PNIPAM-12K, Mn 12,000 g mol(-1)) were studied by 1D and 2D (1)H and (13)C NMR spectroscopy, isothermal calorimetry (ITC), and light scattering (LS). In cold water (T < 26 °C) supramolecular "dumbbell" assemblies, consisting of PNIPAM chains with β-CD/Ad inclusion complexes at each end, formed viaβ-CD-insertion of the terminal Ads through the β-CD secondary face. Light scattering, microcalorimetry (DSC), and DOSY NMR studies indicated that mixed aqueous solutions of β-CD-PEO7 and Ad-PNIPAM-12K undergo a reversible heat-induced phase transition at ∼32 °C, accompanied by a release of a fraction of the Ad-bound β-CD-PEO7 into bulk solution and the formation of aggregated Ad-PNIPAM-12K stabilized by a β-CD-PEO7 shell.
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