“AD HOC” MODIFIED CLAYS FOR BIOTECHNOLOGICAL APPLICATIONS
Nowadays, the scientific community has to face with cogent problems strictly linked to the improvement of quality of live. Among the different tasks to achieve the prefixed objective the focus has been put on the drug administration, i.e., attention has been paid to propose an appropriate solution to improve the performance of a drug delivery system and to eliminate both the side effect and drawbacks. With the aim to achieve the design, synthesis, and characterization of versatile systems, with peculiar characteristics, based on clays and clays modified with a biocompatible surfactant, able to adsorb and release organic substances of pharmaceutical interest the present PhD thesis has been u…
Porous materials as delivery and protective agents for Vitamin A
The suitability of porous materials to immobilize and release under control bioactive molecules prompted us to design and study delivery systems of Vitamin A (VitA). This molecule, relevant in several physiological functions, is easily oxidized. Commercial VitA was immobilized in two different clays, montmorillonite K-10 (MMT) and sepiolite (SEP), and in MCM-41, by impregnation. Characterization of the resulting hybrid materials by XRD, FTIR and 13C and 29Si (MAS) NMR spectroscopies revealed its presence. The photo-stability tests showed decreased degradation of VitA in the clays, compared to MCM-41 and the pure VitA, while thermostability is observed until ∼100 °C. The kinetics of the rele…
The apparently anomalous effects of surfactants on interfacial tension in the IBA/water system near its upper critical solution temperature
We studied the effect of anionic, cationic, and nonionic surfactants on the interfacial tension between the two phases of the isobutyric acid/water system using spinning drop tensiometry. It has been found that interfacial tension decreases with increasing concentration of the surfactant in the case of sodium dodecyl sulfate (SDS) and of dodecyltrimethylammonium chloride (DTAC). However, in the case of Triton X-100 an increase of surfactant concentration leads to an increase of the interfacial tension. Such results are consistent with the upper critical solution temperature (UCST) in the presence of these surfactants: the UCST decreases with increasing SDS and DTAC concentrations while it i…
Clay-biosurfactant materials as functional drug delivery systems: Slowing down effect in the in vitro release of cinnamic acid
Abstract The main objectives of the present paper were the preparation and characterization of new surfactant-modified clays and the evaluation of their potential applicability as drug delivery systems for the oral administration of the cinnamic acid (CA) drug. The organoclays (OC) were prepared by loading different amounts of the biocompatible nonionic polyoxyethylene sorbitan monolaurate surfactant (Tween20) onto K10 montmorillonite (Mt) clay and characterized through the construction of the adsorption isotherms by means of the spectrophotometric method. The performance of the prepared material was verified by gathering the adsorption isotherms of the cinnamic acid onto the Mt/Tween20 org…
Inorganic Materials as Drug Delivery Systems for Vitamin A
Impact of a Mediterranean Dietary Pattern and Its Components on Cardiovascular Risk Factors, Glucose Control, and Body Weight in People with Type 2 Diabetes: A Real-Life Study
This study evaluates the relation of a Mediterranean dietary pattern and its individual components with the cardiovascular risk factors profile, plasma glucose and body mass index (BMI) in people with type 2 diabetes. We studied 2568 participants at 57 diabetes clinics. Diet was assessed with the EPIC (European Prospective Investigation into Cancer and Nutrition) questionnaire, adherence to the Mediterranean diet was evaluated with the relative Mediterranean diet score (rMED). A high compared to a low score was associated with a better quality of diet and a greater adherence to the nutritional recommendations for diabetes. However, even in the group achieving a high score, only a small prop…
Montmorillonite nanodevices for the colon metronidazole delivery.
The adsorption profiles of the antibiotic metronidazole (MNE) into the K10-montmorillonite (MMT-K10) clay and the subsequent release have been investigated as a function of pH and MNE/MMT-K10 ratio, in order to evaluate the potential of the MNE/MMT-K10 hybrids as controlled drug delivery system. The adsorption mechanism has been first elucidated by performing complementary equilibrium and kinetic studies and through the X-ray diffractometry (XRD) characterization of the obtained composite materials. The gathered results allowed us to propose a mechanism consisting of a multi-step pathway involving the neutral and the cationic form of the drug, which interact with different sites of the clay…
Synthesis and characterization of taylor-made organo-clays for biotechnological applications
New tailor-made bio-organoclays for the remediation of olive mill waste water
A systematic study aimed at obtaining new organoclays for the treatment of Olive Mill Waste water (OMW) has been performed. Several organoclays have been prepared by loading different amounts of the biocompatible surfactant Tween20 onto the K10 montmorillonite (MMT). Complementary kinetic and equilibrium studies on the adsorption of the Tween20 onto the MMT have been carried out and the characterization of the new tailor-made bio-materials has been performed by means of the XRD and FT-IR measurements. Finally the prepared bio-organoclays have been successfully applied for the OMW remediation and they proved to be highly effective in decreasing the organic content (OC) to an extent that depe…
Modified Montmorillonite as Drug Delivery Agent for Enhancing Antibiotic Therapy
The appealing properties of surfactant-intercalated Montmorillonites (Organo-montmorillonite, OMt) were successfully investigated to propose an effective drug delivery system for metronidazole (MNE) antibiotic therapy. This represents a serious pharmaceutical concern due to the adverse drug reactions and the low targeting ability of MNE. The non-ionic surfactant Tween 20 was used to functionalize montmorillonite, thus accomplishing the two-fold objective of enhancing the stability of clay dispersion and better controlling drug uptake and release. The adsorption process was performed under different experimental conditions and investigated by constructing the adsorption isotherms through hig…
Preparation and characterization of bio-organoclays using nonionic surfactant
The present study was aimed at the preparation and characterization of tailor made hybrid materials, whose peculiar hosting capability could be exploited in biotechnological applications. With this purpose, the modification of K10 montmorillonite by intercalation of Tween 20 surfactant, was accomplished. The influence of two internal parameters, namely pH and surfactant/clay ratio, on the surfactant uptake ability by clay was investigated. The adsorption mechanism was elucidated on the basis of complementary kinetic and equilibrium studies and, then, corroborated by the useful information provided by the FT-IR, TGA and XRD characterization. The gathered results allow to draw the conclusion …
Deconvolution procedure of the UV-vis spectra. A powerful tool for the estimation of the binding of a model drug to specific solubilisation loci of bio-compatible aqueous surfactant-forming micelle
UV-vis-spectra evolution of Nile Red loaded into Tween 20 micelles with pH and [Tween 20] have been analysed in a non-conventional manner by exploiting the deconvolution method. The number of buried sub-bands has been found to depend on both pH and bio-surfactant concentration, whose positions have been associated to Nile Red confined in aqueous solution and in the three micellar solubilisation sites. For the first time, by using an extended classical two-pseudo-phases-model, the robust treatment of the spectrophotometric data allows the estimation of Nile Red binding constant to the available loci. Hosting capability towards Nile Red is exalted by the pH enhancement. Comparison between bin…