Georgi Yordanov- Ph.D. ; D.Sc.
- Professor (Associate) at Sofia University "St. Kliment Ohridski"
Georgi Yordanov
- Ph.D. ; D.Sc.
- Professor (Associate) at Sofia University "St. Kliment Ohridski"
Looking for potential collaborations and involvement in various research projects in the areas of my publications.
About
74
Publications
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Introduction
Georgi Yordanov (Ph.D., D.Sc.) currently works as associate professor at the Faculty of Chemistry and Pharmacy, Sofia University "St. Kliment Ohridski". Dr. Yordanov does research in nanomaterials, nanobiochemistry and nanotechnology. Their most recent publication is 'Preparation and characterization of nanostructured ferric hydroxyphosphate adjuvants'.
Current institution
Additional affiliations
October 2009 - November 2009
July 2009 - present
January 2009 - December 2012
Publications
Publications (74)
Investigation and novel data on the interactions between blood plasma proteins and polysorbate 80-coated poly(butyl cyanoacrylate) (PBCA) drug nanocarriers determined by surface plasmon resonance (SPR) are reported. For that purpose, human blood plasma proteins (albumin, immunoglobulin G and fibrinogen) were immobilized on the surface of SPR sensor...
Copolymers of styrene and maleic acid of relatively low molecular weight possess a great potential for application as components of drug delivery systems, especially in cancer chemotherapy. The pioneering research in this area has been performed in the 1980s during the development of macromolecular complexes for selective drug delivery to solid tum...
Objective: Drug loading into nanocarriers is used to facilitate drug delivery to target cells and organs. We have previously reported a change in cellular localization of epirubicin after loading to poly(butyl cyanoacrylate) (PBCA) nanoparticles. We aimed to further investigate the altered cellular localization and cellular responses to the describ...
Poly(butyl cyanoacrylate) (PBCA) nanoparticles have numerous applications, including drug and gene delivery, molecular imaging, and cancer therapy. To uncover the molecular mechanisms underlying their interactions with cell membranes, we utilized a Langmuir monolayer as a model membrane system. This approach enabled us to investigate the processes...
Poly(butyl cyanoacrylate) (PBCA) nanoparticles have numerous applications, including drug and gene delivery, molecular imaging, and cancer therapy. To uncover the molecular mechanisms underlying their interactions with cell membranes, we utilized a Langmuir monolayer as a model membrane system. This approach enabled us to investigate the processes...
Here we present data on the preparation and adsorption properties of mixed zinc-calcium phosphates in aqueous dispersions. The phosphates were prepared by co-precipitation from aqueous solutions followed by autoclaving. The effects of various Ca/Zn initial molar ratios and the type of Ca-and Zn-precursor salts (chlorides and acetates) on the struct...
Introduction
The blood microbiome is still an enigma. The existence of blood microbiota in clinically healthy individuals was proven during the last 50 years. Indirect evidence from radiometric analysis suggested the existence of living microbial forms in erythrocytes. Recently targeted nucleic acid sequencing demonstrated rich microbial biodiversi...
Removal of heavy metals ions from water sources still represents a challenge and different materials are being developed in order to overcome it. Iron oxide nanomaterials receive a lot of attention because of their small size, high surface area, biocompatibility and low cost. However, most of the reported synthesis methods are multi-step and time-c...
This article presents the preparation and characterization of various calcium-magnesium phosphate suspensions with particular focus on nanostructured magnesium whitlockite as potential protein adsorbent. The phosphates were synthesized by precipitation from mixed Ca(II)/Mg(II) solutions with disodium hydrogen phosphate followed by thermal treatment...
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Ferric phosphate has been proposed for vaccine adjuvant use and therefore studies on its preparation and physicochemical properties are highly required in order to achieve reproducibility of production and optimal adsorption capacity for protein antigens. Here, we report on the protein adsorption properties of nanostructured ferric phosphate adjuva...
Vaccine adjuvants are key components of inactivated vaccines that potentiate the immune response to antigens. Nanostructured gels of aluminium-containing sparingly soluble compounds, such as aluminium oxyhydroxide and hydroxyphosphate, are widely used as immunological adjuvants in currently licensed human and veterinary vaccines. Here, we report on...
This chapter considers the pharmacology of poly(alkyl cyanoacrylate) (PACA) nanoparticles intended for use in anticancer therapeutics. It is particularly focused on some illustrative and promising formulations of cytostatics with PACA nanoparticles, their pharmacokinetics, toxicology, in vivo studies in animals, and results from recent clinical tri...
This article describes part of the results obtained during the development of a new generation of vaccine adjuvants based on nanostructured hydroxyphosphates of tunable composition and physicochemical characteristics. Colloidal gels of ferric hydroxyphosphates of various iron/phosphate ratios were prepared by precipitation techniques, sterilized by...
Adjuvants are substances that, when combined with an antigen in a vaccine formulation, potentiate the immune response against that antigen. Aluminium hydroxyphosphate is among the currently used adjuvants in vaccines, while studies on its iron analogue, ferric hydroxyphosphate, are quite limited. In this article we report on the preparation and phy...
In this study, the preparation of poloxamer 188-coated poly(butyl cyanoacrylate) colloidal nanospheres of controlled size distribution and their physicochemical characterisation were investigated and their cytotoxic effects in cervical carcinoma (HeLa) cells evaluated. The nanoparticles were prepared by controlled emulsion polymerisation of butyl c...
We present the results from low temperature studies of the PL from colloidal CdSe nanocrystals prepared by the hot injection method in liquid paraffin. The synthesized nanocrystals were all within the quantum confinement range and showed the typical size-dependent UV-vis absorption, PL and Raman spectral characteristics. The photoluminescence spect...
This article describes the results from low temperature studies of the photoluminescence (PL) from colloidal CdSe nanocrystals prepared by the hot injection method in liquid paraffin. The synthesized nanocrystals were taken from the reaction mixture at different time intervals, their sizes were all within the quantum confinement range, and showed t...
This article describes studies on the efficiency of activated carbon as adsorbent for water-dispersible silver nanoparticles. Nanoparticles of average size around 60 nm and negative zeta-potential were synthesized by reduction of Ag(I) ions with sodium citrate in aqueous medium. Activated carbon (Norit® CA1) intended for water purification was foun...
This article describes the influence of the preparation method on the physicochemical properties of econazole-loaded poly(butyl cyanoacrylate) nanoparticles. The nanoparticles were prepared by using two different methods – nanoprecipitation and emulsion polymerization. Three different non-ionic colloidal stabilizers (poloxamer 188, polysorbate 80 a...
This article describes the preparation, physicochemical characterization and cytotoxicity assessment of novel colloidal formulations of etoposide based on poly(butyl cyanoacrylate) nanoparticles. Nanoparticles were prepared by controlled emulsion polymerization of butyl cyanoacrylate in aqueous medium using two different non-ionic colloidal stabili...
Fluorescent polystyrene microspheres are prepared by the incorporation of fluorescent CdSe/CdS core/shell semiconductor nanocrystals
(quantum dots, QDs) using the emulsification/solvent evaporation method. The radiative exciton recombination dynamics is investigated
by nanosecond time-resolved fluorescence spectroscopy at ambient conditions. The ti...
First prepared in 1979, the colloidal nanoparticles based on
biocompatible and bioerosive poly(alkyl cyanoacrylate) materials are
still under investigation and hold promise for the development of novel
formulations for targeted drug delivery. Different types of poly(alkyl
cyanoacrylate) nanoparticles have been developed during the last 33
years, su...
This article considers the preparation and physicochemical characterization of a novel colloidal formulation of the β-lactam antibiotic cephalexin, loaded in poly(ethyl cyanoacrylate) colloidal nanospheres. The drug was loaded by means of drug incorporation in the interior of poly(ethyl cyanoacrylate) particles during the polymerization of the resp...
This report describes the preparation of poly(butyl cyanoacrylate) nanospheres loaded with epirubicin by nanoprecipitation, their characterization and in vitro evaluation of the drug uptake and cytotoxicity on cancer cell lines. The epirubicin-loaded nanospheres were prepared by nanoprecipitation using presynthesized polymer and dextran 40 as a col...
This paper describes the preparation and characterization of poly(ethyl cyanoacrylate) colloidal particles loaded with the
organic fluorophore Rhodamine 6G. We studied the physicochemical properties of the colloidal particles: morphology, size-distribution,
ζ-potential, fluorescent properties and photobleaching upon UV-light illumination. The prope...
This article presents a systematic investigation of the optical properties and the growth process of CdTe nanocrystals during
their hot-injection-based synthesis in liquid paraffin. Cadmium(II) stearate and tributylphosphine telluride are used as precursors.
The as-obtained nanocrystals are characterized by transmission electron microscopy (TEM) wi...
This review considers the present status and the prospects for future
development of the bioimaging applications of quantum dots. The preparation and optical
characteristics of quantum dots are discussed, as well as the general strategies for their
post-synthetic chemical modifi cations, which are required in order to obtain biocompatible
fl uoresc...
The colloidal particles of poly(alkyl cyanoacrylate) (PACA) posses a great promise as drug carrier systems for delivery of anticancer drugs, antibiotics and other pharmaceutics. Such particles are classically prepared by emulsion polymerization, starting from the respective monomer. Our recent studies demonstrate that pure and drug-loaded PACA coll...
Poly(n-butylcyanoacrylate) submicron colloidal particles loaded with the antibiotic ciprofloxacin are prepared by emulsion polymerization
and characterized by scanning electron microscopy, dynamic light scattering, nuclear magnetic resonance and gel-permeation
chromatography. The entrapment efficiency for ciprofloxacin in the polymer particles is i...
The aim of the present study is the preparation and physicochemical characterization of chlorambucil-loaded poly(butylcyanoacrylate)
nanoparticles. Chlorambucil is a lipophilic drug, which is used clinically against chronic lymphocytic leukemia, lymphomas,
and other types of malignant diseases. However, the chlorambucil use is limited by its chemic...
Classically, drug-loaded poly(alkylcyanoacrylate) colloidal carriers are prepared by the drug entrapment during emulsion polymerization.
However, a number of chemically sensitive drugs are unstable in the conditions of polymerization or can be irreversibly inactivated
by the highly reactive monomer. Furthermore, the particle size distribution and t...
Patterned thin films, ZnO, are successfully prepared on glass substrates by the sol-gel method using dip-coating technique.
The films, formed of ZnO nanocrystallites with hexagonal crystal structure, are characterized by means of scanning electron
microscopy, Fourier transform infrared spectroscopy and X-ray diffraction. The as obtained ZnO films a...
Nanoparticles of poly(butylcyanoacrylate) loaded with the antineoplastic drug chlorambucil are prepared by two different methods: dispersion polymerization and nanoprecipitation. Both preparation methods involve the formation of nanoparticles in aqueous medium in the presence of dextran 40 as a colloidal stabilizer. Butylcyanoacrylate monomer is us...
This report considers the formulation stability and antibacterial activity of ciprofloxacin-loaded nanoparticles of poly(butylcyanoacrylate). The polymer nanoparticles are prepared by emulsion polymerization of butylcyanoacrylate in acidic aqueous solution of ciprofloxacin lactate and Pluronic F68. The obtained nanoparticles are characterized by sc...
Thioglycolate-coated quantum dots represent an important class of nanoparticles widely used as fluorescent materials. Although the synthesis of water-dispersible quantum dots is a routine procedure, little is known about the mechanism of nanocrystal formation and growth at these conditions. Here, we present a study on the nanocrystal growth of thio...
Nanostructured ZnO thin films were deposited on glass by the dip-coating sol–gel method. The films exhibited pronounced activity
to destroy malachite green in water both under UV-light illumination and in the dark.
Here we report the synthesis and physicochemical characterization of novel hybrid core/shell type ZnO/poly(ethylcyanoacrylate)
colloidal particles. It is expected that coating ZnO colloidal particles with biocompatible and biodegradable poly(alkylcyanoacrylates)
will pave the way toward the potential application of ZnO colloidal particles in biomed...
Fluorescent quantum dots (QDs) tagged poly(butylcyanoacrylate) nanoparticles (PBCN) intended for cell fluorescent imaging were prepared and characterized. Highly fluorescent CdSe/CdS core-shell QDs were synthesized and successfully embedded into PBCN by interfacial polymerization in aqueous medium. Transmission electron microscopy, dynamic light sc...
This work presents the observation of a photo-activated fluorescence from core/shell quantum dots of CdSe/CdS incorporated in a poly(butylmethacrylate) matrix. Upon illumination with UV-light, the intensity of fluorescence from the quantum dots increases as seen by naked eyes at ambient conditions. This allows its utilization in optical memory medi...
Fluorescent core-shell CdSe/CdS quantum dots were successfully encapsu-lated into polystyrene microparticles using an emulsifi cation/solvent evaporation method. For that purpose core-shell quantum dots of CdSe/CdS were synthesized, purifi ed and dispersed in polystyrene solution. After emulsifi cation in water using non-ionic surfactant, the organ...
Thin TiO2 films, dotted with ZnS nanoparticles synthesized by the hot-matrix method, result in appreciably better photocatalytic destruction
of organic pollutants in water and air than the non-dotted films.
Here, we report a novel strategy to prepare fluorescent semiconductor quantum dots (QDs) of core–shell type with CdSe–CdS
QDs as a model system. Our synthesis was carried out in liquid paraffin, which is a natural, nontoxic, and cheap solvent.
We applied a single injection of precursor for the shell growth at low temperature and gradual heating of...
Although stearic acid is a widely used amphiphilic compound in hot-matrix syntheses of quantum dots, the effect of its concentration has not been studied in details in order to achieve better control over the nanocrystal growth process. Here we systematically investigate various mixtures of stearic acid and non-coordinating solvent (paraffin) as th...
We proved that various organic solvents react with elemental chalcogens (sulfur and selenium) by liberating hydrogen chalcogenide
(H2X, X = S, Se) during the phosphine-free hot-matrix synthesis of quantum dots. The in situ-produced H2X reacts further with the metal salt to form the corresponding nanosized metal chalcogenide CdX. The effect of tempe...
The growth process of CdSe nanocrystals synthesized in paraffin hot-matrix is studied. The complex combination of nucleation, growth and ripening processes in the first stages of nanocrystal growth is known as early time ripening. It is found that the early time ripening depends on the synthesis temperature and the concentration of Se-precursor (tr...
This paper describes the optical and structural properties of CdS nanoparticles during their growth in paraffin hot-matrix containing stearic acid ligand. The nanocrystalline species are characterized with absorbance and photoluminescence spectroscopy, fluorescence microscopy, High-Resolution Transmission Electron Microscopy and X-ray diffraction....
The present paper describes the influence of the sulfur precursor on the nanocrystal growth rate and optical properties of cadmium sulfide nanocrystals in a hot-paraffin matrix. One of the precursors used is tributylphosphine sulfide; the other one is elemental sulfur. The growth kinetics is studied at various temperatures to estimate the activatio...
This paper describes the temperature and the ligand type dependence of the growth kinetics of CdSe nanoparticles synthesized by a version of the hot-matrix method. In this method the composite matrix comprises a non-coordinating solvent (liquid paraffin) and a coordinating ligand (carboxylic acid). As a Cd-precursor serves cadmium carboxylate in si...
Semiconductor nanocrystals are of a great interest for many practical applications which motivates the search of low cost and environmental-friendly methods for their manufacturing. Here we report the synthesis of CdSe and CdS nanoparticles utilizing composite matrix of liquid paraffin as a non-coordinating solvent and stearic acid as a coordinatin...
The formation of CdSe nanocrystals in hot matrix comprising liquid paraffin and molten trioctylphosphine oxide (TOPO) is studied using a kinetic model for the growth of nanoparticles at different composition of the matrix. It is found that the radius of initial nuclei and the final nanoparticle radius decrease while the rate constant of the crystal...
Here we describe the synthesis of ZnO nanocrystals in alcoholic solutions of zinc acetate dihydrate in the presence of different additives: ethanolamine (ETA), trioctylphosphine oxide (TOPO), octylphenol ethoxylate-10 (Triton X-100), laureth-3 (Rokanol LK3) and laureth-10 (Rokanol L10). The optical properties of the obtained ZnO nanocrystals are in...
Questions
Question (1)
There are numerous articles about development of various chitosan-based nanoparticles for parenteral drug/gene/vaccine delivery but I was unsuccessful to find any references about the pharmacokinetics of these nanoparticles. Are they degradable inside cell endosomes? Could such nanoparticles ever be eliminated from the organism after parenteral administration?
