Martha Kafetzi

National Hellenic Research Foundation

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Co-Authors

Stergios Pispas

National Hellenic Research Foundation

Despoina Giaouzi

National Hellenic Research Foundation

Nikos Tagmatarchis

National Hellenic Research Foundation

Raúl Arenal

Instituto de Nanociencia y Materiales de Aragón

Anastasios Stergiou

Politecnico di Milano

Theodore Sentoukas

Centre of Polymer and Carbon Materials

Ioanna K. Sideri

National Hellenic Research Foundation

Varvara Chrysostomou

National Hellenic Research Foundation

Angeliki Chroni

National Centre of Scientific Research "Demokritos"

Andriana Plantzopoulou

National Hellenic Research Foundation

Cooperative Institutions

National Hellenic Research Foundation

Leibniz Institute of Polymer Research

Alexandria University

Mohammed V University

Athens State University

National and Kapodistrian University of Athens

Ain Shams University

Consejo Nacional de Investigaciones Científicas y Técnicas

Dr. Hari Singh Gour University

University of Crete

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A solution-processed MoS₂/graphene heterostructure mediated by a bifunctional block copolymer as a non-noble metal platform for hydrogen evolution

Sustainable Energy & Fuels (2022)

Andriana Plantzopoulou Ioanna K. Sideri Anastasios Stergiou Martha Kafetzi Stergios Pispas

A molybdenum disulfide/graphene heterostructure exhibiting excellent HER performance was prepared and characterized.

Noble metal

10.1039/d2se00218c

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Citations (1)

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)

Multifaceted pH and Temperature Induced Self‐Assembly of P(DMAEMA‐co‐LMA)‐b‐POEGMA Terpolymers and Their Cationic Analogues in Aqueous Media

Macromolecular Chemistry and Physics (2021)

Martha Kafetzi Stergios Pispas

Abstract This work focuses on the synthesis of novel amphiphilic block terpolymers of the type poly[(2‐( N,N ‐dimethylamino) ethyl methacrylate)‐ co ‐(lauryl methacrylate)]‐ b ‐poly[(oligo ethylene glycol) methyl ether methacrylate] (P(DMAEMA‐ co ‐LMA)‐ b ‐POEGMA)) by reversible addition‐fragmentation chain transfer polymerization. The cationic amphiphilic polyelectrolyte analogs P(QDMAEMA‐ co ‐LMA)‐ b ‐POEGMA are obtained through quantitative quaternization of the DMAEMA segments. Molecular characterization by size exclusion chromatography, nuclear magnetic resonance, and Fourier Transform Infrared spectroscopies indicates the successful synthesis of these novel series of block terpolymers. The amine forms of the block copolymers respond to pH and temperature changes in aqueous solutions by forming unimolecular or multichain nanoaggregates of varying size, micropolarity, and internal structure, as indicated by light scattering and fluorescence spectroscopy techniques. At neutral and basic pH, the existence of micellar like nanoassemblies is observed in the solutions of P(DMAEMA‐ co ‐LMA)‐ b ‐POEGMA terpolymers, while aggregation into micellar‐like clusters take place at temperature values above room temperature due to the presence of the hydrophobic LMA segments. Unexpectedly, the cationic polyelectrolytes P(QDMAEMA‐ co ‐LMA)‐ b ‐POEGMA counterparts show temperature responsiveness as a consequence of the amphiphilicity of the polymeric system.

Cationic polymerization

10.1002/macp.202000358

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Citations (13)

Polymeric Nanostructures Containing Proteins and Peptides for Pharmaceutical Applications

Polymers (2022)

Antiopi Vardaxi Martha Kafetzi Stergios Pispas

Over the last three decades, proteins and peptides have attracted great interest as drugs of choice for combating a broad spectrum of diseases, including diabetes mellitus, cancer, and infectious and neurological diseases. However, the delivery of therapeutic proteins to target sites should take into account the obstacles and limitations related to their intrinsic sensitivity to different environmental conditions, fragile tertiary structures, and short half-life. Polymeric nanostructures have emerged as competent vehicles for protein delivery, as they are multifunctional and can be tailored according to their peculiarities. Thus, the enhanced bioavailability and biocompatibility, the adjustable control of physicochemical features, and the colloidal stability of polymer-based nanostructures further enable either the embedding or conjugation of hydrophobic or hydrophilic bioactive molecules, which are some of the features of paramount importance that they possess and which contribute to their selection as vehicles. The present review aims to discuss the prevalent nanostructures composed of block copolymers from the viewpoint of efficient protein hospitality and administration, as well as the up-to-date scientific publications and anticipated applications of polymeric nanovehicles containing proteins and peptides.

Biocompatibility

10.3390/polym14040777

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Citations (14)

Amphiphilic QP(DMAEMA-co-LMA)-b-POEGMA Random-Block Terpolymers as Nanocarriers for Insulin

Biomedicines (2020)

Martha Kafetzi Stergios Pispas Xiaoyan Bao Ping Yao

We report on the utilization of the amphiphilic poly[quaternized (2-(N,N-dimethylamino) ethyl methacrylate)]-co-(lauryl methacrylate))-b-poly[(oligo ethylene glycol) methyl ether methacrylate] QP(DMAEMA-co-LMA)-b-POEGMA cationic diblock terpolymer aggregates as nanocarriers for insulin delivery applications. QP(DMAEMA-co-LMA)-b-POEGMA random diblock terpolymer is derived from the chemical modification of the precursor amino diblock copolymer via quaternization, producing permanent positive charges on the macromolecular chain. The QP(DMAEMA-co-LMA)-b-POEGMA diblock terpolymer as well as its amino precursor investigated self-assemble in aqueous media, forming aggregates. In vitro cytotoxicity and in vivo biocompatibility studies on QP(DMAEMA-co-LMA)-b-POEGMA and its amino precursor aggregates, showed good cytocompatibility and biocompatibility. QP(DMAEMA-co-LMA)-b-POEGMA aggregates were chosen to be complexed with insulin due to their self-assembly features and the permanent positive charge in each amino group. QP(DMAEMA-co-LMA)-b-POEGMA aggregates were complexed with insulin through electrostatic interactions. Light scattering techniques were used in order to study the ability of the polymer aggregates to complex with insulin, to determine critical physicochemical parameters such as size, mass, and surface charge of the stable complexes and study the effect of salt addition on their properties. The results showed that in both cases, the complexation process was successful and as the insulin concentration increases, nanosized complexes of different physicochemical characteristics (mass, size, surface charge) and spherical morphology are formed. UV-Vis and fluorescence spectroscopy studies showed that no conformational changes of insulin occurred after the complexation.

Nanocarriers

Biocompatibility

10.3390/biomedicines8100392

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Citations (12)

Effects of Hydrophobic Modifications on the Solution Self-Assembly of P(DMAEMA-co-QDMAEMA)-b-POEGMA Random Diblock Copolymers

Polymers (2021)

Martha Kafetzi Stergios Pispas

In this work, the synthesis and the aqueous solution self-assembly behavior of novel partially hydrophobically modified poly(2-(dimethylamino) ethyl methacrylate)-b-poly(oligo(ethylelene glycol) methyl ether methacrylatetabel) pH and temperature responsive random diblock copolymers (P(DMAEMA-co-Q6/12DMAEMA)-b-POEGMA), are reported. The chemical modifications were accomplished via quaternization with 1-iodohexane (Q6) and 1-iodododecane (Q12) and confirmed by 1H-NMR spectroscopy. The successful synthesis of PDMAEMA-b-POEGMA precursor block copolymers was conducted by RAFT polymerization. The partial chemical modification of the diblocks resulted in the permanent attachment of long alkyl chains on the amine groups of the PDMAEMA block and the presence of tertiary and quaternary amines randomly distributed within the PDMAEMA block. Light scattering techniques confirmed that the increased hydrophobic character results in the formation of nanoaggregates of high mass and tunable pH and temperature response. The characteristics of the aggregates are also affected by the aqueous solution preparation protocol, the nature of the quaternizing agent and the quaternization degree. The incorporation of long alkyl chains allowed the encapsulation of indomethacin within the amphiphilic diblock copolymer aggregates. Nanostructures of increased size were detected due to the encapsulation of indomethacin into the interior of the hydrophobic domains. Drug release studies demonstrated that almost 50% of the encapsulated drug can be released on demand by aid of ultrasonication.

10.3390/polym13030338

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Citations (7)

Methylammonium Lead Bromide Perovskite Nano-Crystals Grown in a Poly[styrene-co-(2-(dimethylamino)ethyl Methacrylate)] Matrix Immobilized on Exfoliated Graphene Nano-Sheets

Nanomaterials (2022)

Anastasios Stergiou Ioanna K. Sideri Martha Kafetzi Άννα Ιωάννου Raúl Arenal

Development of graphene/perovskite heterostructures mediated by polymeric materials may constitute a robust strategy to resolve the environmental instability of metal halide perovskites and provide barrierless charge transport. Herein, a straightforward approach for the growth of perovskite nano-crystals and their electronic communication with graphene is presented. Methylammonium lead bromide (CH3NH3PbBr3) nano-crystals were grown in a poly[styrene-co-(2-(dimethylamino)ethyl methacrylate)], P[St-co-DMAEMA], bi-functional random co-polymer matrix and non-covalently immobilized on graphene. P[St-co-DMAEMA] was selected as a bi-modal polymer capable to stabilize the perovskite nano-crystals via electrostatic interactions between the tri-alkylamine amine sites of the co-polymer and the A-site vacancies of the perovskite and simultaneously enable Van der Waals attractive interactions between the aromatic arene sites of the co-polymer and the surface of graphene. The newly synthesized CH3NH3PbBr3/co-polymer and graphene/CH3NH3PbBr3/co-polymer ensembles were formed by physical mixing of the components in organic media at room temperature. Complementary characterization by dynamic light scattering, microscopy, and energy-dispersive X-ray spectroscopy revealed the formation of uniform spherical perovskite nano-crystals immobilized on the graphene nano-sheets. Complementary photophysical characterization by UV-Vis absorption, steady-state, and time-resolved fluorescence spectroscopy unveiled the photophysical properties of the CH3NH3PbBr3/co-polymer colloid perovskite solution and verified the electronic communication within the graphene/CH3NH3PbBr3/co-polymer ensembles at the ground and excited states.

10.3390/nano12081275

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Citations (4)

Ecofriendly Removal of Aluminum and Cadmium Sulfate Pollution by Adsorption on Hexanoyl-Modified Chitosan

Polysaccharides (2022)

Berthold Reis Konstantin B. L. Borchert Martha Kafetzi Martin Müller Karina Haro Carrasco

The purity and safety of water as a finite resource is highly important in order to meet current and future human needs. To address this issue, the usage of environmentally friendly and biodegradable adsorbers and flocculants is essential. Chitosan, as a biopolymer, features tremendous properties as an adsorber and flocculant for water treatment. For the application of chitosan as an adsorber under acidic aqueous conditions, such as acid mine drainage, chitosan has been modified with hydrophobic hexanoyl chloride (H-chitosan) to reduce the solubility at a lower pH. In order to investigate the influence of the substitution of the hexanoyl chloride on the adsorption properties of chitosan, two chitosans of different molecular weights and of three different functionalization degrees were analyzed for the adsorption of CdSO4(aq) and Al2(SO4)3(aq). Among biobased adsorbents, H-chitosan derived from the shorter Chitosan exhibited extraordinarily high maximum adsorption capacities of 1.74 mmol/g and 2.06 mmol/g for Cd2+ and sulfate, and 1.76 mmol/g and 2.60 mmol/g for Al3+ and sulfate, respectively.

Biopolymer

Aluminium sulfate

Environmental Pollution

10.3390/polysaccharides3030035

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Citations (5)

Hybrid Perovskite/Polymer Materials: Preparation and Physicochemical Properties

Journal of Composites Science (2021)

Martha Kafetzi Stergios Pispas G.A. Mousdis

The aim of this work is to investigate the preparation, the optical properties, and the stability over time of a colloidal organic–inorganic hybrid perovskite (CH3NH3PbBr3)/random copolymer P(MMA-co-DMAEMA) system. Different ratios of perovskite to copolymer were used to study its effect on stability and properties. The optical properties were investigated by UV-Vis and fluorescence spectroscopy. Dynamic light scattering was used to determine the size, and the size polydispersity of the colloidal hybrid particles; while morphology was investigated by transmission electron microscopy. Photoluminescence decay studies revealed the interaction of the random copolymer with the perovskite. Finally, thin-films were prepared, to investigate the optical properties of the samples in the absence of the solvent. High temporal stability of the optical properties of thin hybrid films was observed under certain conditions.

Dispersity

Hybrid material

10.3390/jcs5110304

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Citations (3)

Self-Aggregation in Aqueous Media of Amphiphilic Diblock and Random Block Copolymers Composed of Monomers with Long Side Chains

Langmuir (2023)

Sapir Rappoport Varvara Chrysostomou Martha Kafetzi Stergios Pispas Yeshayahu Talmon

Amphiphilic diblock copolymers and hydrophobically modified random block copolymers can self-assemble into different structures in a selective solvent. The formed structures depend on the copolymer properties, such as the ratio between the hydrophilic and the hydrophobic segments and their nature. In this work, we characterize by cryogenic transmission electron microscopy (cryo-TEM) and dynamic light scattering (DLS) the amphiphilic copolymers poly(2-dimethylamino ethyl methacrylate)-b-poly(lauryl methacrylate) (PDMAEMA-b-PLMA) and their quaternized derivatives QPDMAEMA-b-PLMA at different ratios between the hydrophilic and the hydrophobic segments. We present the various structures formed by these copolymers, including spherical and cylindrical micelles, as well as unilamellar and multilamellar vesicles. We also examined by these methods the random diblock copolymers poly(2-(dimethylamino) ethyl methacrylate)-b-poly(oligo(ethylene glycol) methyl ether methacrylate) (P(DMAEMA-co-Q6/12DMAEMA)-b-POEGMA), which are partially hydrophobically modified by iodohexane (Q6) or iodododecane (Q12). The polymers with a small POEGMA block did not form any specific nanostructure, while a polymer with a larger POEGMA block formed spherical and cylindrical micelles. This nanostructural characterization could lead to the efficient design and use of these polymers as carriers of hydrophobic or hydrophilic compounds for biomedical applications.

Side chain

10.1021/acs.langmuir.2c03294

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Citations (5)