Metal species interaction with biological

In this section we summarise the manner in which i -metals. Fig. 6, and where possible specifically the platinum complexes of concern here, interact with biological molecules. Some radio-tracer studies have been carried out on the distribution of platinum complexes in whole bacteria grown in media inocculated with the metal ion. The results are summarised in Table 11. It is noteworthy that the bacteriocidal complex [PtClg]2- was taken up almost entirely by the cytoplasmic protein whereas the filamentous forming neutral species, [Pt(NHs)2Cl4], was... 

Figure 9.3 The role of ROS in the possible mechanisms by which nanomaterials interact with biological systems. ROS generation is associated with all the four aspects of the mechanisms, in which examples illustrate the importance of material composition, electronic structure, bonded surface species (e.g., metal-containing), surface coatings (active or passive), and solubility, including the contribution of surface species and coatings and interactions with other environmental factors (e.g., UV activation).

A complex set of interrelationships involving physical, chemical, biological, and pharmacological factors are involved when a metal ion interacts with a biological system. Therefore, it is more important to characterize the metal-biological system than to characterize the species in a simple chemical system. In a comprehensive work. Walker et al. (2003) reviewed approximately 100 diverse contributions dating from 1835 to 2003 to evaluate the relationships between about 20 physicochemical properties of cations and their potential to produce toxic effects in different organisms. 

Interaction of Metal Species with Biological Interphases. 241... 

INTERACTION OF METAL SPECIES WITH BIOLOGICAL INTERPHASES... 

In biological systems metals and metalloids not only interact with high molecular mass constituents, for example proteins and DNA, but also with a host of low molecular mass ligands, amino acids, peptides, inorganic ligands and others. The above discussion also apply to these species. A fraction of some elements are unbound and these could be treated as hydrated free ions. 

Polylactones (for an example, see Fig. 14.4) are synthetic analogues of naturally occurring ionophores such as enniatin (species that transport ions across biological membranes). Molecular mechanics calculations have been used to predict the stability and selectivity with respect to Li+, Na+, and K+ of a series of new polylactones12661. Metal-ligand interactions were again modeled using a combination of van der Waals and electrostatic terms. 

The different biological effects of NO and HNO are a function of distinct molecular targets for these redox siblings. For example, NO preferentially reacts with reduced metals to directly form a nitrosyl complex (Eq. 13). The identical product is formed by reductive nitrosylation of HNO toward oxidized metals (Eq. 12). Exceptions of course exist (e.g., the reverse of Eq. 19). Perhaps more importantly, HNO reacts with thiols (Eq. 21) and amines (Eq. 25) directly while NO must interact with these species indirectly, following oxidation to a nitrosating or oxidizing agent (36). 

PEBBLEs are water-soluble nanoparticles based on biologically inert matrices of cross-linked polymers, typically poly(acrylamide), poly(decylmethacrylate), silica, or organically modified silicates (ORMOSILs), which encapsulate a fluorescent chemo-sensor and, often, a reference dye. These matrices have been used to make sensors for pH, metal ions, as well as for some nonionic species. The small size of the PEBBLE sensors (from 20 to 600 nm) enables their noninvasive insertion into a living cell, minimizing physical interference. The semipermeable and transparent nature of the matrix allows the analyte to interact with the indicator dye that reports the interaction via a change in the emitted fluorescence. Moreover, when compared to naked chemosensors, nanoparticles can protect the indicator from chemical interferences and minimize its toxicity. Another important feature of PEBBLEs, particularly valuable in intracellular sensing applications, is that the polymer matrix creates a separate... 

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