Heavy metal pollution in the environment and their toxicological effects on humans

Environmental pollution of heavy metals is increasingly becoming a problem and has become of great concern due to the adverse effects it is causing around the world. These inorganic pollutants are being discarded in our waters, soils and into the atmosphere due to the rapidly growing agriculture and metal industries, improper waste disposal, fertilizers and pesticides. This review shows how pollutants enter the environment together with their fate. Some metals affect biological functions and growth, while other metals accumulate in one or more different organs causing many serious diseases such as cancer. The pharmacokinetics and toxicological processes in humans for each metal is described. In summary, the review shows the physiological and biochemical effects of each heavy metal bioaccumulation in humans and the level of gravity and disquieting factor of the disease.peer-reviewe

The effect of sodium chloride on ethanolic fractionation of dilute gelatin solutions

Gelatin is the denaturation product of the protein collagen, the main constituent of animal skin, bone, and connective tissue. The conversion of collagen to gelatin results in a heterogeneous product with a broad molecular weight profile (MWP), which is important in determining the behaviour of the protein in solution. Addition of successive increments of a non-solvent, such as ethanol, to gelatin solutions causes the Florey- Huggins solvent-protein interaction parameter, χ, of the system to successively exceed the critical value for the different molecular weight fractions, causing progressive desolvation of the polymer. When sufficient solvent molecules are removed, the gelatin molecules begin to aggregate, resulting in phase separation, and forming a coacervate or, if sufficient desolvation occurs, a precipitate. Modification of the net charge of the protein molecules, by adjusting the solution pH to values ranging about the iso-electric point (IEP), influences the degree of interaction between the different molecular weight fractions, and hence the response of the protein to non-solvent.1 It can be hypothesised that alteration of the molecular charge intensity by changes in the ionic strength of the solution would affect the overall response of the protein. The objective of this work was to determine the effect of dilute NaCl concentrations on the response of B225 and B75 gelatins to the non-solvent ethanol at different pH’s.peer-reviewe

Quality by design optimisation of active pharmaceutical ingredient dispersions based on physicochemical parameters

Current information lacks richness in systematic methods that may give an indication as to the effectiveness of a specific set of dispersing conditions prior to their application, particularly for dispersions in hydrophobic media. This study addressed the possibility of constructing a predictive model that may indicate the effectiveness of a specific set of dispersion conditions prior to their application, particularly for dispersions in hydrophobic media. In particular, the objectives were to determine the physicochemical characteristics of the dispersing media that are potentially influential in the dispersability of powders, to characterise the properties of the active pharmaceutical ingredients that could contribute to the ability to form stable dispersions, and to characterise the dispersions of the active pharmaceutical ingredients (APIs) in the dispersing media or dispersing media-surfactant mixtures.peer-reviewe

The effect of alloying elements on the properties of pressed and non-pressed biodegradable Fe–Mn–Ag powder metallurgy alloys

Current trends in the biodegradable scaffold industry call for powder metallurgy methods in which compression cannot be applied due to the nature of the scaffold template itself and the need to retain the shape of an underlying template throughout the fabrication process. Iron alloys have been shown to be good candidates for biomedical applications where load support is required. Fe–Mn alloys were researched extensively for this purpose. Current research shows that all metallurgical characterisation and corrosion test on Fe–Mn and Fe–Mn–Ag non pre-alloyed powder alloys are performed on alloys which are initially pressed into greens and subsequently sintered. In order to combine the cutting-edge field of biodegradable metallic alloys with scaffold production, metallurgical characterisation of pressed and non-pressed Fe, Fe–Mn and Fe–Mn–Ag sintered elemental powder compacts was carried out in this study. This was performed along with determination of the corrosion rate of the same alloys in in vitro mimicking solutions. These solutions were synthesised to mimic the osteo environment in which the final scaffolds are to be used. Both pressed and non-pressed alloys formed an austenite phase under the right sintering conditions. The corrosion rate of the non-pressed alloy was greater than that of its pressed counterpart. In a potentiodynamic testing scenario, addition of silver to the alloy formed a separate silver phase which galvanically increased the corrosion rate of the pressed alloy. This result wasn't replicated in the non-pressed alloys in which the corrosion rate was seen to remain similar to the non-silver-bearing alloy counterparts.peer-reviewe

The effect of Sodium Dodecyl Sulfate on the ethanolic fractionation of dilute gelatin solutions

Gelatin is a heterogeneous protein with a broad molecular weight profile (MWP), which determines its behaviour in solution. Addition of a non-solvent, such as ethanol, to aqueous gelatin solutions causes progressive desolvation of the polymer. When sufficient solvent molecules are removed, the gelatin molecules begin to aggregate, resulting in phase separation, and forming a coacervate or, if sufficient desolvation occurs, a precipitate.1 Sodium dodecyl sulphate (SDS) associates with gelatin through hydrophobic interactions involving the hydrocarbon tail, and through ionic interactions between the negatively charged headgroup of SDS and positively charged side groups on the gelatin molecule; both mechanisms cause unfolding of the protein and yield a hydrophobic complex.2 It can be hypothesised that addition of SDS to dilute gelatin solutions will affect their desolvation behaviour, depending on the degree of binding of SDS to gelatin at different pH’s. The objective of this work was to determine the effect of dilute SDS concentrations on the response of B225 gelatin to the non-solvent ethanol at different pH’s.peer-reviewe

Influence of pH and gelatin concentration on the size and zeta potential of gelatin colloidal dispersions

Gelatin is a heterogeneous mixture of water-soluble proteins. Its broad molecular weight profile may be responsible for the variation in the experimental conditions required for nanoparticle formation. Since this may hinder the application of gelatin nanoparticles, it is important to determine the effect of several factors on the properties and stability of primary dispersions. The phase behaviour of gelatin in ethanol-water binary solvent systems has already been studied using transmittance values. The objective of this project was to use dynamic light scattering and laser Doppler electrophoresis to increase the understanding of the effects of pH and various dilute gelatin concentrations on the size, polydispersity and zeta potential of dispersions of B225 bovine skin gelatin in hydroalcoholic solutions.peer-reviewe

The influence of pH, temperature and salt on the ethanolic desolvation of dilute cold water fish skin gelatin from aqueous solution

Gelatin is a heterogeneous mixture of water-soluble proteins of high molecular weight. It is the degradation product of the protein collagen, a long triple-stranded helical rod which is stabilized by non-covalent interactions and covalent crosslinking. A number of studies have been carried on the desolvation of various types of gelatin of mammalian origin.1,2 Cold-water fish skin gelatin (CWFSG) has a different imino acid composition to mammalian gelatin. The number of proline and hydroxylproline groups in CWFSG is lower and this means that there is less hydrogen bonding. This leads to a different secondary structure. Moreover, the differences in the primary structure of the protein would also be expected to cause differences in other physical properties fish gelatin may exhibit. The objective of this work was to determine the response of CWFSG in aqueous solution, to the non- solvent ethanol under different conditions of pH, temperature and concentration.peer-reviewe

Potentiometric studies on gelatin solutions and gelatin nanoparticle dispersions

Gelatin is the denaturation product of the protein collagen. The denaturation can be performed by acid hydrolysis or base hydrolysis rendering A- type or B-type gelatin respectively. Gelatin molecules have a nonuniform distribution of 18 amino acids. As a typical protein, gelatin carries both positive and negative charges. Table 1 lists the main amino acids present in gelatin that can contribute towards the presence of a charge on a gelatin macromolecule, together with their respective pKa's.peer-reviewe

Physicochemical aspects of the higher order structure of gelatin in dilute aqueous solution

The conversion of collagen to gelatin results in a heterogeneous product with a broad molecular weight profile (MWP). Addition of a non-solvent, such as ethanol, to gelatin solutions gradually causes the Florey-Huggins solvent-protein interaction parameter to exceed the critical value for the different molecular weight fractions, causing desolvation of the polymer. When sufficient solvent molecules are removed, the gelatin molecules begin to aggregate, resulting in phase separation, and forming a coacervate. Modification of the net charge of the protein, by adjusting the solution pH to values ranging about the iso-electric point (IEP), influences the degree of interaction between the different molecular weight fractions, and hence the response of the protein to non-solvent.peer-reviewe

Validation of X-ray fluorescence spectrometer technique to determine heavy metal concentrations in soil samples

Heavy metal soil pollution had increased in recent years and this has produced adverse effects to human wellbeing’s health by being uptaken in the food chain. A potential threat of heavy metal pollution was suspected at the Government Farm in Għammieri. This is due to heavy traffic and fireworks causing concern to the farmers who cultivate fruit and vegetables in these fields. Soil sampling with an instrument that can give rapid results was needed to analyse the data and give the real-time in-situ mapping of heavy metal pollution in the soil. Comparison between an X-Ray Fluorescent (XRF) spectrometer and an Inductively Coupled Plasma – Mass Spectrometer (ICP-MS), both of which are conventional analytical techniques, was performed to measure the heavy metals in the soil by using laboratory and field work. This was performed to make sure that the XRF that was being used, would give accurate results before testing larger sample size. The XRF used was situated at the Department of Chemistry, at the University of Malta, whilst the ICP-MS was situated in Germany, at an accredited laboratory. Five samples were collected from around the whole field, where each sample was split into 2 identical batches.peer-reviewe