Maria Karayianni

National Hellenic Research Foundation

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Stergios Pispas

National Hellenic Research Foundation

Grigoris Mountrichas

National Hellenic Research Foundation

Aurel Rădulescu

Heinz Maier-Leibnitz Zentrum

Marcela Mihai

Institutul de Chimie Macromoleculară Petru Poni

Elena-Daniela Lotos

Institutul de Chimie Macromoleculară Petru Poni

ΝP

Νatassa Pippa

National and Kapodistrian University of Athens

Theodore Sentoukas

Centre of Polymer and Carbon Materials

Aristeidis Papagiannopoulos

National Hellenic Research Foundation

Despoina Giaouzi

National Hellenic Research Foundation

Athanasios Skandalis

National Hellenic Research Foundation

Cooperative Institutions

National Hellenic Research Foundation

Alexandria University

Bulgarian Academy of Sciences

Institute of Polymers

National and Kapodistrian University of Athens

Institutul de Chimie Macromoleculară Petru Poni

Centre National de la Recherche Scientifique

Mohammed V University

Ain Shams University

Dr. Hari Singh Gour University

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Polymeric micelles for therapeutics and diagnosis

Elsevier eBooks (2023)

Maria Karayianni Angeliki Chroni Varvara Chrysostomou Despoina Giaouzi Martha Kafetzi

10.1016/b978-0-323-85785-7.00019-x

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Citations (1)

FTIR real-time monitoring of the adsorption of PS-b-PEO copolymers on Ge from micellar solutions

Maria Karayianni Κ. Gatsouli Georgios D. Chryssikos V. Gionis Stergios Pispas

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Self-Assembly of Amphiphilic Block Copolymers in Selective Solvents

Springer series on fluorescence (2016)

Maria Karayianni Stergios Pispas

Polymersome

10.1007/978-3-319-26788-3_2

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Citations (69)

Complexation of stimuli-responsive star-like amphiphilic block polyelectrolyte micelles with lysozyme

Soft Matter (2012)

Maria Karayianni Stergios Pispas

The complexation between the stimuli-responsive star-like polyelectrolyte micelles formed by the self-assembly of polystyrene-b-poly(sodium(sulfamate-carboxylate)isoprene) (PS-SCPI) amphiphilic diblock copolymer in water and hen egg white lysozyme (HEWL) was investigated by means of dynamic, static and electrophoretic light scattering. Due to the pH-dependent charge density of the SCPI polyelectrolyte block and surface charge distribution of HEWL, the complexation process was studied at both pH 7 and pH 3 (high and low charge density of the SCPI block, or low and high net positive charge of HEWL, respectively) and at low ionic strength conditions. The solution behavior, structure and effective charge of the formed complexes proved to be dependent on the ratio of the two components and the pH of the solution. Moreover, it was found that the degree of charge neutralization caused by complexation determines the conformation and solubility of the complexes. Increasing the ionic strength of the solution led to vast aggregation of the preformed complexes and even precipitation in some cases. The structural investigation of the complexed protein by fluorescence, circular dichroism and infrared spectroscopic measurements revealed no signs of denaturation upon complexation.

Electrophoretic light scattering

Charge density

Surface charge

Carboxylate

Coacervate

10.1039/c2sm26084k

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Citations (14)

Natural–Synthetic Hybrid Nanostructures Formed Through the Interaction of Chitosan with Carboxylate-Ended PNIPAM: Structure and Curcumin Encapsulation

Nanomaterials (2025)

Elena-Daniela Lotos Maria Karayianni Ana‐Lavinia Vasiliu Marcela Mihai Stergios Pispas

Chitosan is widely used in drug delivery applications, due to its biocompatibility, bio-degradability, and low toxicity. Nevertheless, its properties can be enhanced through the physical or chemical modification of its amino and hydroxyl groups. This work explores the electrostatic complexation of two chitosan samples of differing lengths with two poly(N-isopropylacrylamide) (PNIPAM) homopolymers of different molecular weight carrying a chargeable carboxyl end group. This interaction enables the electrostatic binding of PNIPAM side chains onto the chitosan backbone through the amino groups, and could be considered as an alternative grafting method. Dynamic and electrophoretic light scattering techniques were employed in order to study the solution/dispersion properties of the formed complexes as a function of the PNIPAM concentration, or, equivalently, the molar/charge ratio of the two components. The obtained results revealed that their mass, size, and charge mostly depend on the length of the two individual constituents, as well as their mixing ratio. Furthermore, their response to changes in their environment, namely temperature and ionic strength, was also examined, demonstrating the effect of either the thermoresponsiveness of PNIPAM or the electrostatic charge screening, respectively. Fluorescence spectroscopy, utilizing pyrene as a probe, provided information regarding the hydrophobicity of the formed complexes, while images from scanning transmission electron and atomic force microscopies further elucidated their morphology, which was found to be closely related to that of the corresponding chitosan molecule. Finally, their potential as drug delivery vehicles was also investigated, utilizing curcumin as a model drug at various loading concentrations.

Encapsulation

Carboxylate

10.3390/nano15050350

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Block copolymer solution self‐assembly: Recent advances, emerging trends, and applications

Journal of Polymer Science (2021)

Maria Karayianni Stergios Pispas

Abstract The self‐assembly process of block copolymers (BCPs) in solution has been at the focus of extended scientific research over the past several decades owing to the astonishing morphological diversity and attainable complexity of the resulting nanoassemblies, including spheres, cylinders, lamellae, vesicles, and many other complex, bicontinuous or even hierarchical structures. The ever‐increasing sophistication in the development of synthetic chemistry methods and techniques has led to a myriad of available macromolecules with varying chemical compositions, architectures, features, and properties. This assortment of characteristics has led in turn to a plethora of intriguing self‐organized polymeric nanostructures, with countless possible applications in several nanotechnological fields relevant to physics, chemistry, material science, nanomedicine, and biomaterials. The present review aims to illuminate the importance and fascinating potential of BCPs solution self‐assembly by highlighting recent advances and emerging trends in the field, as well as significant application‐oriented progress, through characteristic contemporary examples.

Sophistication

10.1002/pol.20210430

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Citations (142)

Formation of complexes in aqueous solutions of amphiphilic triblock polyelectrolytes of different topologies and an oppositely charged protein

Soft Matter (2018)

Aristeidis Papagiannopoulos Maria Karayianni Stergios Pispas Aurel Rădulescu

The complexation of lysozyme with aggregates from two triblock amphiphilic polyelectrolytes of the same blocks but different topologies and block molar masses, namely PS-b-SCPI-b-PEO and SCPI-b-PS-b-PEO, is investigated by scattering and spectroscopy methods. Light scattering reveals that the interaction with lysozyme causes shrinkage of the self-assembled nanoparticles in the case of the hydrophobic-polyelectrolyte-hydrophilic sequence. In the polyelectrolyte-hydrophobic-hydrophilic sequence, the opposite trend is observed. Small angle neutron scattering confirms the existence of micellar and fractal aggregates and the complexation with lysozyme. The pH-dependence of the interactions and the stability of the hybrid protein/polymer nanoparticles upon salt addition are tested. The native conformation of the protein is found to be preserved during complexation. This study reveals that both micellar and fractal aggregates made of amphiphilic triblock polyelectrolytes are capable of loading with oppositely charged proteins in a controllable manner, tuned primarily by the structure of the triblock terpolymer.

Hydrophobic effect

10.1039/c8sm00208h

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Development of Double Hydrophilic Block Copolymer/Porphyrin Polyion Complex Micelles towards Photofunctional Nanoparticles

Polymers (2022)

Maria Karayianni Dimitra Koufi Stergios Pispas

The electrostatic complexation between double hydrophilic block copolymers (DHBCs) and a model porphyrin was explored as a means for the development of polyion complex micelles (PICs) that can be utilized as photosensitive porphyrin-loaded nanoparticles. Specifically, we employed a poly(2-(dimethylamino) ethyl methacrylate)-b-poly[(oligo ethylene glycol) methyl ether methacrylate] (PDMAEMA-b-POEGMA) diblock copolymer, along with its quaternized polyelectrolyte copolymer counterpart (QPDMAEMA-b-POEGMA) and 5,10,15,20-tetraphenyl-21H,23H-porphine-p,p′,p″,p′′′-tetrasulfonic acid tetrasodium hydrate (TPPS) porphyrin. The (Q)PDMAEMA blocks enable electrostatic binding with TPPS, thus forming the micellar core, while the POEGMA blocks act as the corona of the micelles and impart solubility, biocompatibility, and stealth properties to the formed nanoparticles. Different mixing charge ratios were examined aiming to produce stable nanocarriers. The mass, size, size distribution and effective charge of the resulting nanoparticles, as well as their response to changes in their environment (i.e., pH and temperature) were investigated by dynamic and electrophoretic light scattering (DLS and ELS). Moreover, the photophysical properties of the complexed porphyrin along with further structural insight were obtained through UV-vis (200-800 nm) and fluorescence spectroscopy measurements.

10.3390/polym14235186

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Citations (5)

Complex Formation Between Lysozyme and Stabilized Micelles with a Mixed Poly(ethylene oxide)/Poly(acrylic acid) Shell

The Journal of Physical Chemistry B (2016)

Maria Karayianni Valeria Gancheva Stergios Pispas Petar Petrov

The electrostatic complexation between lysozyme and stabilized polymeric micelles (SPMs) with a poly(acrylic acid) (PAA) or a mixed poly(ethylene oxide)/poly(acrylic acid) (PEO/PAA) shell (SPMs with a mixed shell, SPMMS) and a temperature-responsive poly(propylene oxide) (PPO) core was investigated by means of dynamic, static, and electrophoretic light scattering. The SPMs and different types of SPMMS used resulted from the self-assembly of PAA-PPO-PAA triblock copolymer chains, or PAA-PPO-PAA and PEO-PPO-PEO triblock copolymer chain mixtures (with varying chain lengths and molar ratios) in aqueous solutions at pH 10 and the subsequent cross-linking of their PPO cores via loading and photo-cross-linking of pentaerythritol tetraacrylate (PETA). The solution behavior, structure and properties of the formed complexes at pH 7 and 0.01 M ionic strength, were studied as a function of the protein concentration in the solution (the concentration of the stabilized micelles was kept constant) or equivalently the ratio of the two components. The complexation process and properties of the complexes proved to be dependent on the protein concentration, while of particular interest was the effect of the structure of the shell of the SPMs on the stability/solubility of the complexes. Finally, the fluorescence and mid infrared spectroscopic investigation of the structure of the complexed protein showed that, although a small stretching of the protein molecules occurred in some cases, no protein denaturation takes place upon complexation.

Acrylic acid

Poly ethylene

10.1021/acs.jpcb.6b00550

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Citations (4)

Self-Assembled Nanoparticles from a Block Polyelectrolyte in Aqueous Media: Structural Characterization by SANS

The Journal of Physical Chemistry B (2010)

Aristeidis Papagiannopoulos Maria Karayianni Grigoris Mountrichas Stergios Pispas Aurel Rădulescu

We present a small angle neutron scattering (SANS) study of polystyrene-b-sodium (sulfamate/carboxylate) isoprene (PS-PSCI) nanoparticles in aqueous media. The SANS experiments are complemented by static and dynamic light scattering measurements. A detailed analysis of the scattering form factor obtained by SANS for the self-assembled block polyelectrolyte spherical nanoparticles implies a two-region power-law model for the radial volume fraction profiles. The theoretically predicted scaling of the osmotic brush regime ϕ(r) ∼ r−2 for the inner region and the osmotic annealing brush regime ϕ(r) ∼ r−8/3 for the outer region are in agreement with our experimental findings. A concentrated shell of PSCI polyelectrolyte chains collapsed on the polystyrene core is needed in the form factor analysis so that the aggregation number of the nanoparticles is self-consistent. The self-assembled nanoparticles are found to be kinetically frozen i.e. their aggregation number is not sensitive to the solution conditions and is defined by the preparation protocol. The size of the spherical nanoparticles tends to decrease upon the addition of salt and the drop of pH.

Volume fraction

Polystyrene

10.1021/jp1009912

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Citations (12)