A rapid non-equilibrium critical precipitation assay to assess aluminium-ligand interactions

Jugdaohsingh, Ravin; Afsharrad, Seppidah; McCrohan, Catherine R.; White, Kenneth; Thompson, R. P. H.; Powell, Jonathan J.

doi:10.3184/095422904782775063

Cited by 3 publications

(5 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The re-dissolution of HSP is greatly reduced by binding trace amounts of Al(III) to form ASP. It is known that soluble Al(III) inhibits the decomposition of polymeric silica and reduces the solubility of amorphous silica in water [ 25 , 31 ]. Aluminum adsorbs onto the silica surface and prevents attack by hydroxyl ions [ 25 , 32 ].…”

Section: Discussionmentioning

confidence: 99%

High-Aluminum-Affinity Silica Is a Nanoparticle That Seeds Secondary Aluminosilicate Formation

et al. 2013

Self Cite

View full text Add to dashboard Cite

Despite the importance and abundance of aluminosilicates throughout our natural surroundings, their formation at neutral pH is, surprisingly, a matter of considerable debate. From our experiments in dilute aluminum and silica containing solutions (pH ~ 7) we previously identified a silica polymer with an extraordinarily high affinity for aluminium ions (high-aluminum-affinity silica polymer, HSP). Here, further characterization shows that HSP is a colloid of approximately 2.4 nm in diameter with a mean specific surface area of about 1,000 m2 g-1 and it competes effectively with transferrin for Al(III) binding. Aluminum binding to HSP strongly inhibited its decomposition whilst the reaction rate constant for the formation of the β-silicomolybdic acid complex indicated a diameter between 3.6 and 4.1 nm for these aluminum-containing nanoparticles. Similarly, high resolution microscopic analysis of the air dried aluminum-containing silica colloid solution revealed 3.9 ± 1.3 nm sized crystalline Al-rich silica nanoparticles (ASP) with an estimated Al:Si ratio of between 2 and 3 which is close to the range of secondary aluminosilicates such as imogolite. Thus the high-aluminum-affinity silica polymer is a nanoparticle that seeds early aluminosilicate formation through highly competitive binding of Al(III) ions. In niche environments, especially in vivo, this may serve as an alternative mechanism to polyhydroxy Al(III) species binding monomeric silica to form early phase, non-toxic aluminosilicates.

show abstract

Section: Discussionmentioning

confidence: 99%

High-Aluminum-Affinity Silica Is a Nanoparticle That Seeds Secondary Aluminosilicate Formation

et al. 2013

Self Cite

View full text Add to dashboard Cite

show abstract

“…After further washing twice, in pH 10 water, particles were dissolved in 100 mM citric acid buffer (pH 3) to release the organic material. Total protein content was measured using the Bradford protein assay (as per manufacturer’s protocol, Bio-Rad Laboratories, UK) while PGN matter was quantified using both a colorimetric assay and a modified Periodic Acid Schiff (PAS) assay as described ( 21 ).…”

Section: Methodsmentioning

confidence: 99%

Reduction of T-Helper Cell Responses to Recall Antigen Mediated by Codelivery with Peptidoglycan via the Intestinal Nanomineral–Antigen Pathway

et al. 2017

Self Cite

View full text Add to dashboard Cite

Naturally occurring intestinal nanomineral particles constituently form in the mammalian gut and trap luminal protein and microbial components. These cargo loaded nanominerals are actively scavenged by M cells of intestinal immune follicles, such as Peyer’s patches and are passed to antigen-presenting cells. Using peripheral blood mononuclear cell populations as an in vitro model of nanomineral uptake and antigen presentation, we show that monocytes avidly phagocytose nanomineral particles bearing antigen and peptidoglycan (PGN), and that the presence of PGN within particles downregulates their cell surface MHC class II and upregulates programmed death receptor ligand 1. Nanomineral delivery of antigen suppresses antigen-specific CD4+ T cell responses, an effect that is enhanced in the presence of PGN. Blocking the interleukin-10 receptor restores CD4+ T cell responses to antigen codelivered with PGN in nanomineral form. Using human intestinal specimens, we have shown that the in vivo nanomineral pathway operates in an interleukin-10 rich environment. Consequently, the delivery of a dual antigen–PGN cargo by endogenous nanomineral in vivo is likely to be important in the establishment of intestinal tolerance, while their synthetic mimetics present a potential delivery system for therapeutic applications targeting the modulation of Peyer’s patch T cell responses.

show abstract

“…Gastrointestinal fluids and model solutions were assessed for their Al-binding capacity as previously described (Jugdaohsingh et al, 2001;Jugdaohsingh et al, 2004). Briefly, for model solutions (100 mmol L -1 MOPS with 1.8% m/v NaCl, pH 2) with a fixed ligand concentration (20 mmol L -1 ), 2.5 mL aliquots were mixed with 2.5 mL increasing Al concentration (7-30.6 mmol L -1 Al) and the pH adjusted to 7.0 with NaOH.…”

Section: Aluminium Binding Assaysmentioning

confidence: 99%

“…Gastric juice bound a minimum 0.17 mmol L -1 Al ( Figure 3A) although, with high concentrations of Al, the total levels of Al held in solution fell (Jugdaohsingh et al, 2004), reaching baseline levels of 0.02 mmol L -1 with 11.2 mmol L -1 Al added. Again, maximum binding capacities of human bile, either at its natural pH or pre-acidified to pH 2, were not established as peak values were not found ( Figure 3B).…”

Section: Aluminium Binding Capacities Of Gastrointestinal Fluidsmentioning

confidence: 99%

“…Such interactions, which interfere with hydroxypolymerisation of these metals, have not been investigated for Al and, therefore, individual components that may be responsible for the intestinal luminal binding, and hence absorption of soluble Al, have not been identified. We have recently reported a 'critical precipitation' assay (Jugdaohsingh et al, 2001;Jugdaohsingh et al, 2004) for assessing the Al binding capacity of fluids. Here we used this assay as well as high-resolution 1 H -nuclear magnetic resonance spectroscopy ( 1 H NMR) to identify potential components of human gastrointestinal fluids that bind Al.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Application of the critical precipitation assay to complex samples: aluminium binding capacity of human gastrointestinal fluids

Powell

Jugdaohsingh

Piotrowicz

et al. 2004

Chemical Speciation & Bioavailability

Self Cite

View full text Add to dashboard Cite

A rapid non-equilibrium critical precipitation assay to assess aluminium-ligand interactions

Cited by 3 publications

References 16 publications

High-Aluminum-Affinity Silica Is a Nanoparticle That Seeds Secondary Aluminosilicate Formation

High-Aluminum-Affinity Silica Is a Nanoparticle That Seeds Secondary Aluminosilicate Formation

Reduction of T-Helper Cell Responses to Recall Antigen Mediated by Codelivery with Peptidoglycan via the Intestinal Nanomineral–Antigen Pathway

Application of the critical precipitation assay to complex samples: aluminium binding capacity of human gastrointestinal fluids

Contact Info

Product

Resources

About