The aim of this work is to elucidate the structure of the new hydrogel prepared with scleroglucan... more The aim of this work is to elucidate the structure of the new hydrogel prepared with scleroglucan (Sclg) and borax, suitable for drug delivery, applying theoretical approaches, and to explain its very peculiar swelling. The possible linkages with borate ions have been investigated and original parameters for the 4,6-gluco-borate moiety have been introduced. The structures relative to the Sclg chains in the presence of borax and the possible mutual arrangements among the triple helices are given. According to molecular dynamics simulations, the most probable assembly of the chains in the network is proposed, without and in the presence of three tested model drugs with different molecular dimensions: theophylline (TPH), Vitamin B12 (Vit. B12) and myoglobin (MGB). The hydrogel supramolecular structure, formed via chemical and physical linkages among the polysaccharidic chains, is built up taking into account the steric hindrance of the entrapped molecules. It is shown that molecular dynamics analysis can be a useful tool capable to shed some light on the anomalous swelling of the hydrogel, suitable for drug release, giving a new insight on the network structure and the release rate of the guest molecules.
Journal of Pharmaceutical and Biomedical Analysis, 2010
The growth of pharmaceutical counterfeiting is a major public health problem. This growth is resu... more The growth of pharmaceutical counterfeiting is a major public health problem. This growth is resulting in a proportional increase in the number of samples that medicines control laboratories have to test. Thus the need for simple and affordable preliminary screening methods to be used by inspectors to decide in the field whether to collect a sample for further laboratory analysis or not. This paper intends to evaluate the possibility to employ for preliminary examinations of suspicious samples an optical spectrophotometer (colorimeter) used in the graphic industry, capable of measuring the reflectance visible spectrum of solid materials. The colorimeter was tested on original and counterfeited Viagra, Cialis and Levitra by measuring the colour of tablets' surface and of a specific spot of the packages. Various batches of the original drugs were employed both to investigate precision and robustness of the technique and to build spectral libraries. These libraries were used to compare suspicious samples to the corresponding original by means of a wavelength distance pattern recognition method. The method was eventually tested on suspicious samples sized by police authorities in order to evaluate its effectiveness. The device resulted precise and robust toward ambient conditions changes, although some limits emerged: the libraries of original samples need a frequent update and a lower precision is to be expected for tablets which surface is extremely convex.
Journal of Drug Delivery Science and Technology, 2016
Abstract This overview follows the evolution of the studies carried out, mainly during last years... more Abstract This overview follows the evolution of the studies carried out, mainly during last years, on polysaccharide hydrogels, with particular attention on the researches carried out in our department, often in collaboration with other groups in our country and abroad. The review points out the importance of this type of networks for the optimization of drug delivery and targeting in the various forms of macro, micro and nano systems. It is also shown that these materials are suitable for the culture of different types of cells. Release mechanisms are reported and explained by different physico-chemical approaches and by means of molecular dynamics simulations and the anomalous swelling behavior of a scleroglucan/borax hydrogel is thoroughly discussed. The role of polymer combinations forming interpenetrated structures is explained in terms of specific properties which significantly differ from those of the constituent polymers, thus allowing appropriate tailoring of the delivery rates. Finally the wide possibilities of applications of nanogel structures which allow combination therapies for cancer treatment and can be suitable for intracellular targeting are reported. The studies on polysaccharide hydrogels are still in progress and it is underlined that future researches, more focused on the passage from lab to market, should be further stimulated.
α,β-Poly(N-hydroxyethyl)-dl-aspartamide (PHEA) and α,β-polyasparthydrazide (PAHy) are synthetic p... more α,β-Poly(N-hydroxyethyl)-dl-aspartamide (PHEA) and α,β-polyasparthydrazide (PAHy) are synthetic polymers previously studied for biomedical applications. We report here the results of a small-angle X-ray scattering analysis carried out on these two macromolecules in aqueous solution. The data obtained indicate that the two polymers assume remarkably different conformations in aqueous solution, although the backbone is supposed to be the same for the two chains. PHEA can be represented by a random coil conformation, whereas PAHy can be described in terms of an elliptical cylinder characterized by an almost planar structural arrangement with the backbone refolded on itself in a fashion somewhat similar to the β layer of globular proteins. This more rigid conformation of PAHy is related both to the network of hydrogen bonds capable of stabilizing the overall structure and to the lower molecular weight with respect to PHEA. Conformational and energetic analyses of PAHy are also discussed.
The aim of this work is to elucidate the structure of the new hydrogel prepared with scleroglucan... more The aim of this work is to elucidate the structure of the new hydrogel prepared with scleroglucan (Sclg) and borax, suitable for drug delivery, applying theoretical approaches, and to explain its very peculiar swelling. The possible linkages with borate ions have been investigated and original parameters for the 4,6-gluco-borate moiety have been introduced. The structures relative to the Sclg chains in the presence of borax and the possible mutual arrangements among the triple helices are given. According to molecular dynamics simulations, the most probable assembly of the chains in the network is proposed, without and in the presence of three tested model drugs with different molecular dimensions: theophylline (TPH), Vitamin B12 (Vit. B12) and myoglobin (MGB). The hydrogel supramolecular structure, formed via chemical and physical linkages among the polysaccharidic chains, is built up taking into account the steric hindrance of the entrapped molecules. It is shown that molecular dynamics analysis can be a useful tool capable to shed some light on the anomalous swelling of the hydrogel, suitable for drug release, giving a new insight on the network structure and the release rate of the guest molecules.
Journal of Pharmaceutical and Biomedical Analysis, 2010
The growth of pharmaceutical counterfeiting is a major public health problem. This growth is resu... more The growth of pharmaceutical counterfeiting is a major public health problem. This growth is resulting in a proportional increase in the number of samples that medicines control laboratories have to test. Thus the need for simple and affordable preliminary screening methods to be used by inspectors to decide in the field whether to collect a sample for further laboratory analysis or not. This paper intends to evaluate the possibility to employ for preliminary examinations of suspicious samples an optical spectrophotometer (colorimeter) used in the graphic industry, capable of measuring the reflectance visible spectrum of solid materials. The colorimeter was tested on original and counterfeited Viagra, Cialis and Levitra by measuring the colour of tablets' surface and of a specific spot of the packages. Various batches of the original drugs were employed both to investigate precision and robustness of the technique and to build spectral libraries. These libraries were used to compare suspicious samples to the corresponding original by means of a wavelength distance pattern recognition method. The method was eventually tested on suspicious samples sized by police authorities in order to evaluate its effectiveness. The device resulted precise and robust toward ambient conditions changes, although some limits emerged: the libraries of original samples need a frequent update and a lower precision is to be expected for tablets which surface is extremely convex.
Journal of Drug Delivery Science and Technology, 2016
Abstract This overview follows the evolution of the studies carried out, mainly during last years... more Abstract This overview follows the evolution of the studies carried out, mainly during last years, on polysaccharide hydrogels, with particular attention on the researches carried out in our department, often in collaboration with other groups in our country and abroad. The review points out the importance of this type of networks for the optimization of drug delivery and targeting in the various forms of macro, micro and nano systems. It is also shown that these materials are suitable for the culture of different types of cells. Release mechanisms are reported and explained by different physico-chemical approaches and by means of molecular dynamics simulations and the anomalous swelling behavior of a scleroglucan/borax hydrogel is thoroughly discussed. The role of polymer combinations forming interpenetrated structures is explained in terms of specific properties which significantly differ from those of the constituent polymers, thus allowing appropriate tailoring of the delivery rates. Finally the wide possibilities of applications of nanogel structures which allow combination therapies for cancer treatment and can be suitable for intracellular targeting are reported. The studies on polysaccharide hydrogels are still in progress and it is underlined that future researches, more focused on the passage from lab to market, should be further stimulated.
α,β-Poly(N-hydroxyethyl)-dl-aspartamide (PHEA) and α,β-polyasparthydrazide (PAHy) are synthetic p... more α,β-Poly(N-hydroxyethyl)-dl-aspartamide (PHEA) and α,β-polyasparthydrazide (PAHy) are synthetic polymers previously studied for biomedical applications. We report here the results of a small-angle X-ray scattering analysis carried out on these two macromolecules in aqueous solution. The data obtained indicate that the two polymers assume remarkably different conformations in aqueous solution, although the backbone is supposed to be the same for the two chains. PHEA can be represented by a random coil conformation, whereas PAHy can be described in terms of an elliptical cylinder characterized by an almost planar structural arrangement with the backbone refolded on itself in a fashion somewhat similar to the β layer of globular proteins. This more rigid conformation of PAHy is related both to the network of hydrogen bonds capable of stabilizing the overall structure and to the lower molecular weight with respect to PHEA. Conformational and energetic analyses of PAHy are also discussed.
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