Download NEW CARBON MATERIALS - APPLICATION IN CUMULATION AND

NEW CARBON MATERIALS - APPLICATION IN
CUMULATION AND DELIVERY OF ORGANIC
COMPOUNDS (INCLUDING DRUGS)
SUMMARY
The primary objective of this study was to determine the effect of porous structure
and chemical nature of carbon materials surface in the process of phenol and paracetamol
adsorption and desorption from aqueous solutions. Additionally, some possibilities of
carbon materials application as potential carriers of paracetamol in the systems of controlled
drug release was studied.
Two groups of adsorbents were used. The first group included carbon materials CP3
obtained from sucrose. The second group consisted of two series of carbon nanotubes
labeled as A and H. The characteristics of applied carbon materials were based on the
following methods: sorption analysis, thermal analysis, Boehm´s method, SEM and
HRTEM. All the results led to the conclusion that carbon materials are characterized by
well-developed micro-mesoporous structure. Carbon materials CP3 had a spherical
structure, and possess only acidic functional groups on surface. However, carbon nanotubes
had different physicochemical parameters: length and diameter of the tube, number of the
walls, the value of the BET surface area. The results indicated the amphoteric nature due to
simultaneous presence of acidic and basic groups.
Obtained results of adsorption-desorption using the flow method showed that studied
carbon materials are good phenol and paracetamol adsorbents. A correlation was observed
between the amount of acid groups and the amount adsorbates on CP3materials. The impact
of the chemical nature of carbon CP3 on kinetics of sorption processes was also
demonstrated. However, the amounts of organic compounds adsorbed on carbon nanotubes
increased with the values of the BET surface area. The highest sorption capacity of studied
adsorbates was recorded for carbon nanotubes with the highest values of the BET surface
area. It has been shown, that the molecules are adsorbed parallely on the surface of carbon
nanotubes, since this arrangement rises up the energy dispersive interactions between
aromatic ring of the phenol or paracetamol molecules and a carbon matrix.
The results of numerous study and computer simulations clearly indicate that
paracetamol molecules form nanoaggregates in the interstitial channels between nanotubes
and in the pores of activated carbons. Therefore a new method is proposed for thermal
deposition (so-called Hot Melt Deposition HMD) of paracetamol on carbon materials. The
method of carbonaceous material heating with adsorbed drug at high temperatures can be
successfully applied for the preparation of new drug delivery systems with varying
properties. New drug delivery systems were characterized by a variable rate of paracetamol
release and a wide range of desorbed amount of the drug. The porous structure of carbon
materials used affects the kinetics of release. Carbon nanotubes have been very promising
material that can be used as support of drugs in delivery system. In the case of activated
carbons better properties exhibit materials with higher content of mesopores. Performed
MTT tests of nanotubes and drug-loaded nanotubes show that the observed decrease in cell
viability number is caused by the influence of the cytostatic properties of nanotubes - they
inhibit the proliferation of cells. Studied carbon nanotubes are essentially nontoxic.
Obtained results led to the conclusion that carbon materials can be used as potential carriers
of paracetamol.