2-aminoethylphosphonic Acid Research Articles

Ultra-high FRET efficiency NaGdF4: Tb3+-Rose Bengal biocompatible nanocomposite for X-ray excited photodynamic therapy application

The limitation of light penetration depth invalidates the application of photodynamic therapy in deep-seated tumors. X-ray excited photodynamic therapy (X-PDT), which is based on X-rays excited luminescent nanoparticles (XLNP), provides a new strategy for PDT in deep tissues. However, the high X-ray dosage used and non-specific cytotoxicity of the nanoparticle-photosensitizer nanocomposite (NPs-PS) hamper in-vivo X-PDT applications. To address these problems, a simple and efficient NPs-PS nanocomposite using β-NaGdF4: Tb3+ nanoparticles and widely used PS called Rose Bengal (RB) was designed. With perfectly matched spectrum of NPs emission and RB absorption upon X-ray excitation and covalent conjugation of a large amount of RB on NP surfaces to minimize the energy transfer distance, the system demonstrated ultra-high FRET efficiency up to 99.739%, which leads to maximum production of singlet oxygen for PDT with significantly increased anti-tumor efficacy. By 2-aminoethylphosphonic acid surface modification of NPs, excellent biocompatibility was achieved even at a high concentration of 1 mg/mL. The in-vivo X-PDT efficacy was found around 90% of HepG2 tumor growth inhibition with X-ray dose of only 1.5 Gy, which shows the best anti-tumor efficacy at same X-ray dose level reported so far. The present work provides a promising platform for in-vivo X-PDT in deep tumors.

High-performance liquid chromatographic determination of 2-aminoethylphosphonic acid and 2-amino-3-phosphonopropionic acid in seawater matrix using precolumn fluorescence derivatization with o-phthalaldehyde-ethanethiol

2-Aminoethylphosphonic acid (2-AEP) and 2-amino-3-phosphonopropionic acid (2-AP3) are two types of abundant and ubiquitous naturally occurring phosphonates used as sources of phosphorus by many prokaryotic lineages. The potential utilization mechanism of 2-AEP and 2-AP3 in eukaryotic phytoplankton is currently under investigation. However, the lack of suitable analytical methods in saline samples are the limitation of such researches. Herein, a high-performance liquid chromatography (HPLC) method for monitoring 2-AEP and 2-AP3 using precolumn fluorescence derivatization with o-phthalaldehyde-ethanethiol (OPA-ET) in seawater matrix was developed. The derivatization procedure and HPLC conditions were carefully examined, which included optimization of the fluorescence excitation and emission wavelengths, the ammonium acetate concentration and pH of the mobile phase, the OPA-ET reagent content and composition and derivatization time. Because increasing salinity was observed to lower the derivatization efficiency, working standards were freshly prepared in artificial seawater with the same salinity as that of the samples for the quantification of 2-AEP and 2-AP3. The developed HPLC method showed a wide linear response with high linearity (R2 > 0.999) and high repeatability at three concentration levels. The relative standard deviation was less than 4.1% for 2-AEP and less than 1.7% for 2-AP3 (n = 7). The limits of detection for 2-AEP and 2-AP3 in artificial seawater matrix were both 12.0 μg/L. The recoveries were 83.0–104% for 2-AEP and 72.6–98.6% for 2-AP3 in different aqueous samples, including algal culture medium prepared with filtered seawater. These results indicated the matrix effect of this method was insignificant.

Effect of NaOH-EDTA extraction time on the degradation of phosphate compounds

A chemical extraction of soil organic- and poly‑phosphorus (P) with a 0.25 M NaOH +0.05 M ethylenediaminetetraacetic acid (EDTA) solution is the most widely accepted method for 31P NMR measurements. The chemical preservation is often questioned because of inconsistent extraction time (4–16 h) among researchers. In this study, the effect of extraction time on the degradation of common P compounds (phytic acid, pyrophosphate, 2-aminoethylphosphonic acid, adenosine 5′-triphosphate disodium, and tripolyphosphate) was investigated using a spectrophotometric method. No degradation was observed up to 16 h in most of the compounds except for tripolyphosphate. The hydrolytic degradation of tripolyphosphate was retarded initially due to a high ionic strength of the extractant but became apparent after 8 h.

Adsorption behaviors of glyphosate, glufosinate, aminomethylphosphonic acid, and 2-aminoethylphosphonic acid on three typical Baltic Sea sediments

Abstract A batch experiment was conducted to study the adsorption behaviors of glyphosate , glufosinate , aminomethylphosphonic acid (AMPA), and 2-aminoethylphosphonic acid (2-AEP) in marine sediments (mud, silt, and sand) from the Baltic Sea. The experiment took into account the influence of pH, salinity, and temperature on the adsorption behaviors of the studied compounds. In contrast to glufosinate, glyphosate exhibited an adsorption affinity for the three types of sediments. AMPA and 2-AEP showed similar adsorption behaviors on mud and silt, while their adsorption on sand was negligible. The equilibrium adsorption data for glyphosate, AMPA, and 2-AEP on mud and silt fit well with the linear partitioning and Freundlich isotherms, whereas the data for glyphosate on sand could only be fitted with the Freundlich isotherm. The Freundlich distribution coefficients (k f) were in the range of 6.1–259.5 L/kg for glyphosate, 9.2–39.5 L/kg for AMPA, and 7.7–38.5 L/kg for 2-AEP under the experimental conditions of pH 8.1, temperature = 21 °C, and a salt concentration of 8 g/L. The adsorption kinetic was better described by the pseudo-second-order than the pseudo-first-order model, suggesting chemisorption as the adsorption mechanism. The order of adsorption of the compounds on the sediments was: glyphosate > AMPA ≥ 2-AEP > glufosinate. The adsorption capacity of sediments followed the sequence: mud > silt > sand. Increasing the pH, salinity, or temperature of the solution significantly reduced the adsorption capacity of the compounds. The data obtained in this study provide valuable information on the fate and distribution of the investigated phosphonates in the Baltic Sea.

Grafting of Aminoethylphosphonic Acid Monolayers on Titanium Nitride: The Effect of Surface Pretreatments through Electrochemical‐Assisted Oxidation

The surface of titanium nitride (TiN) contains, in addition to nitride compounds, a certain amount of native oxide. This oxide allows the functionalization of TiN with amine‐terminated groups through spontaneous self‐assembly of aminoethylphosphonic acid. However, real industrial applications of titanium nitride, particularly for microelectronics and electrochemistry, require the development of efficient methods to improve the aminoethylphosphonate loading while preserving the main intrinsic characteristics of the TiN substrate. It is demonstrated that surface pretreatment, by either electrochemical anodization or cleaning in H2O2:HCl:H2O mixture, considerably enhances the phosphonic loading. This is the first report on mild oxidation of TiN surface using an acidic peroxide mixture. This electrochemical‐assisted method does not require any electrochemical equipment, and works through simple immersion of the TiN surface in the cleaning solution at room temperature. Moreover, cleaning in this solution leads to a significantly increased quantity of the grafted phosphonate groups via uniform hydroxylation of the entire surface, without altering the behavior of the pristine TiN. The electrochemical anodization technique, which results in quasicomplete conversion of surface TiN compounds to TiO2 under our working conditions, needs further fundamental investigation towards incorporation of oxygen into the TiN lattice.

The influence of salt matrices on the reversed-phase liquid chromatography behavior and electrospray ionization tandem mass spectrometry detection of glyphosate, glufosinate, aminomethylphosphonic acid and 2-aminoethylphosphonic acid in water

The analysis of highly polar and amphoteric compounds in seawater is a continuing challenge in analytical chemistry due to the possible formation of complexes with the metal cations present in salt-based matrices. Here we provide information for the development of analytical methods for glyphosate, glufosinate, AMPA, and 2-AEP in salt water, based on studies of the effects of salt matrices on reversed-phase liquid chromatography–heated electrospray ionization-tandem mass spectrometry (RP-LC-HESI–MS/MS) after derivatization of the target compounds with FMOC-Cl. The results showed that glyphosate was the only analyte with a strong tendency to form glyphosate-metal complexes (GMC), which clearly influenced the analysis. The retention times (RTs) of GMC and free glyphosate differed by approximately 7.00min, reflecting their distinct RP-LC behaviors. Divalent cations, but not monovalent (Na+, K+) or trivalent (Al3+, Fe3+) cations, contributed to this effect and their influence was concentration-dependent. In addition, Cu2+, Co2+, Zn2+, and Mn2+ prevented glyphosate detection whereas Ca2+, Mg2+, and Sr2+ altered the retention time. At certain tested concentrations of Ca2+ and Sr2+ glyphosate yielded two peaks, which violated the fundamental rule of LC, that under the same analytical conditions a single substance yields only one LC-peak with a specific RT. Salt-matrix-induced ion suppression was observed for all analytes, especially under high salt concentrations. For glyphosate and AMPA, the use of isotopically labeled internal standards well-corrected the salt-matrix effects, with better results achieved for glufosinate and 2-AEP with the AMPA internal standard than with the glyphosate internal standard. Thus, our study demonstrated that Ca2+, Mg2+, and Sr2+ can be used together with FMOC-Cl to form GMC-FMOC which is suitable for RP-LC-HESI–MS/MS analysis.

Amino-Functionalized Layered Crystalline Zirconium Phosphonates: Synthesis, Crystal Structure, and Spectroscopic Characterization.

Two new layered zirconium phosphonates functionalized with amino groups were synthesized starting from aminomethylphosphonic acid in the presence of different mineralizers, and their structures were solved from powder X-ray diffraction data. Their topologies are unprecedented in zirconium phosphonate chemistry: the first, of formula ZrH[F3(O3PCH2NH2)], prepared in the presence of hydrofluoric acid, features uncommon ZrO2F4 units and a remarkable thermal stability; the second, of formula Zr2H2[(C2O4)3(O3PCH2NH2)2]·2H2O, prepared in the presence of oxalic acid, is based on ZrO7 units with oxalate anions coordinated to the metal atom, which were never observed before in any zirconium phosphonate. In addition, the structure of another compound based on (2-aminoethyl)phosphonic acid is reported, which was the object of a previously published study. This compound has layered α-type structure with -NH3(+) groups located in the interlayer space. All of the reported compounds were further characterized by means of vibrational spectroscopy, which provided important information on fine structural details that cannot be deduced from the powder X-ray diffraction data.

PhnW-PhnX Pathway in Dinoflagellates Not Functional to Utilize Extracellular Phosphonates

Phosphorus (P) is an essential nutrient for marine phytoplankton but its preferred form, dissolved inorganic phosphorus (DIP), is often limited in the euphotic zone of the ocean. Many phytoplankton species have developed the ability to utilize dissolved organic phosphorus (DOP) such as phosphoesters or phosphonates. Phosphonates are characterized by the stable C-P bond and its utilization is known to rely on either a C-P lyase pathway or C–P hydrolase pathways in bacteria. In this study by transcriptomic analysis we detected the genes encoding the C-P hydrolase pathway enzymes PhnW and PhnX in Karlodinium veneficum and other dinoflagellates. However, we found that these dinoflagellates are unable to utilize the presumably dominant type of phosphonate in the ocean, 2-aminoethylphosphonic acid (2-AEP), under the antibiotic-treated condition. In accordance, our RT-qPCR and proteomic analyses of K. veneficum grown on 2-AEP showed no up-regulation of PhnW and PhnX at both transcriptional and translational levels. Nevertheless, the genes related to phosphonate biosynthesis and utilization were widely found in dinoflagellates. Taken together our results suggest that the PhnW-PhnX pathway in dinoflagellates may serve for intracellular phosphonate metabolism instead of scavenging environmental phosphonates.

Structure of PhnZ reveals a novel oxygenase mechanism for C-P bond cleavage

Inorganic phosphate is an essential component of many biological molecules and processes including cellular signaling, generation of metabolic energy, DNA and RNA, and membrane phospholipids. Organophosphonates, which contain a highly stable carbon-phosphorus bond, are widely used as herbicidal, chelation, anti-scale, and medicinal agents. PhnY and PhnZ consist of a new oxidative catabolic pathway that is employed by marine bacteria to use 2-aminoethylphosphonic acid as a source of inorganic phosphate. PhnZ is notable for catalyzing the oxidative cleavage of a carbon-phosphorus bond using Fe(II) and dioxygen (see figure), despite belonging to a large family of hydrolytic enzymes, the HD-phosphohydrolase superfamily. We have determined structures of PhnZ in complex with its substrate, (R)-2-amino-1-hydroxyethylphosphonate. The structure reveals PhnZ to have an active site containing two Fe ions bound by 4 histidines and 2 aspartates (see figure) that is strikingly similar to the carbon-carbon bond cleaving enzyme, myo-inositol-oxygenase. Site-directed mutagenesis and kinetic analysis with substrate analogues revealed the roles of key active site residues. A 5th histidine that is conserved in the PhnZ subfamily specifically interacts with the substrate 1-hydroxyl. The structure also revealed that PhnZ possesses a unique induced-fit mechanism whereby an active-site aspartate specifically recognizes the 2-amino group of the substrate and toggles the release of an aromatic residue from the active site, thereby creating space for molecular oxygen bind to the second Fe ion. Structural comparisons of PhnZ reveal an evolutionary connection between Fe(II)-dependent hydrolysis of phosphate esters and oxidative carbon-phosphorus or carbon-carbon bond cleavage, thus uniting the diverse chemistries that are found in the HD superfamily.

Crystal structure of PhnZ in complex with substrate reveals a di-iron oxygenase mechanism for catabolism of organophosphonates.

The enzymes PhnY and PhnZ comprise an oxidative catabolic pathway that enables marine bacteria to use 2-aminoethylphosphonic acid as a source of inorganic phosphate. PhnZ is notable for catalyzing the oxidative cleavage of a carbon-phosphorus bond using Fe(II) and dioxygen, despite belonging to a large family of hydrolytic enzymes, the HD-phosphohydrolase superfamily. We have determined high-resolution structures of PhnZ bound to its substrate, (R)-2-amino-1-hydroxyethylphosphonate (2.1 Å), and a buffer additive, l-tartrate (1.7 Å). The structures reveal PhnZ to have an active site containing two Fe ions coordinated by four histidines and two aspartates that is strikingly similar to the carbon-carbon bond cleaving enzyme, myo-inositol-oxygenase. The exception is Y24, which forms a transient ligand interaction at the dioxygen binding site of Fe2. Site-directed mutagenesis and kinetic analysis with substrate analogs revealed the roles of key active site residues. A fifth histidine that is conserved in the PhnZ subclade, H62, specifically interacts with the substrate 1-hydroxyl. The structures also revealed that Y24 and E27 mediate a unique induced-fit mechanism whereby E27 specifically recognizes the 2-amino group of the bound substrate and toggles the release of Y24 from the active site, thereby creating space for molecular oxygen to bind to Fe2. Structural comparisons of PhnZ reveal an evolutionary connection between Fe(II)-dependent hydrolysis of phosphate esters and oxidative carbon-phosphorus or carbon-carbon bond cleavage, thus uniting the diverse chemistries that are found in the HD superfamily.

2-Aminoethylphosphonate Utilization by the Cold-Adapted Geomyces pannorum P11 Strain

Cold-adapted strain of Geomyces pannorum P11 was found to mineralize of phosphorus–carbon bond-containing compound—2-aminoethylphosphonic acid (2-AEP, ciliatine). The biodegradation process proceeded in the phosphate-independent manner. Ciliatine-metabolizing enzymes' activity was detectable in cell-free extracts prepared from psychrophilic G. pannorum pregrown on 4 mM 2-AEP. Phosphonoacetaldehyde hydrolase (phosphonatase) activity in a partially purified extract was demonstrated at 10 °C.

Soil organic phosphorus transformations in a boreal forest chronosequence

Soil phosphorus (P) composition changes with ecosystem development, leading to changes in P bioavailability and ecosystem properties. Little is known, however, about how soil P transformations proceed with ecosystem development in boreal regions. We used 1-dimensional 31P and 2-dimensional 1H, 31P correlation nuclear magnetic resonance (NMR) spectroscopy to characterise soil organic P transformations in humus horizons across a 7,800 year-old chronosequence in Vasterbotten, northern Sweden. Total soil P concentration varied little along the chronosequence, but P compounds followed three trends. Firstly, the concentrations of DNA, 2-aminoethyl phosphonic acid, and polyphosphate, increased up to 1,200–2,700 years and then declined. Secondly, the abundances of α– and β—glycerophosphate, nucleotides, and pyrophosphate, were higher at the youngest site compared with all other sites. Lastly, concentrations of inositol hexakisphosphate fluctuated with site age. The largest changes in soil P composition tended to occur in young sites which also experience the largest shifts in plant community composition. The apparent lack of change in total soil P is consistent with the youth and nitrogen limited nature of the Vasterbotten chronosequence. Based on 2D NMR spectra, around 40 % of extractable soil organic P appeared to occur in live microbial cells. The observed trends in soil organic P may be related to shifts in plant community composition (and associated changes in soil microorganisms) along the studied chronosequence, but further studies are needed to confirm this.

Organophosphonates revealed: new insights into the microbial metabolism of ancient molecules

Organophosphonates are ancient molecules that contain the chemically stable C-P bond, which is considered a relic of the reducing atmosphere on primitive earth. Synthetic phosphonates now have a wide range of applications in the agricultural, chemical and pharmaceutical industries. However, the existence of C-P compounds as contemporary biogenic molecules was not discovered until 1959, with the identification of 2-aminoethylphosphonic acid in rumen protozoa. Here, we review advances in our understanding of the biochemistry and genetics of microbial phosphonate metabolism, and discuss the role of these compounds and of the organisms engaged in their turnover within the P cycle.

A new experimental and theoretical investigation on the structures of aminoethyl phosphonic acid in aqueous medium based on the vibrational spectra and DFT calculations

A new study on the structural and vibrational properties of the aminoethylphosphonic acid was performed in aqueous solution phase by using the self-consistent reaction field (SCRF) method. We have studied and characterized it by infrared and Raman spectroscopies in solid and aqueous solution phases. The Density Functional Theory (DFT) method with Pople’s basis set show that three stable zwitterions for the title molecule have been theoretically determined in aqueous solution and that probably they are present in it medium. Here, the solvent effects were studied by means of the self-consistent reaction field (SCRF) method with the polarized continuum model (PCM). The harmonic vibrational frequencies for the optimized geometries of the three zwitterions were calculated at the B3LYP/6-31G∗ level of the theory. A complete assignment of the IR and Raman spectra of the compound in aqueous solution was performed combining the DFT calculations with Pulay’s Scaled Quantum Mechanics Force Field (SQMFF) methodology in order to fit the theoretical frequency values to the experimental ones. Moreover, Natural Bond Orbital (NBO) and topological properties calculations were performed to analyze the energies and geometrical parameters of its three zwitterions in aqueous medium as well as the magnitude of the intramolecular interactions. The bond orders, atomic charges, solvation energies, dipole moments, molecular electrostatic potentials and force constants parameters calculated for zwitterions in aqueous solution, may be used to gain chemical and vibrational insights into related compounds.

A Comparative Study of Stabilities and Coordination Modes of β-Alaninephosphonic Acid in Copper(II) Heteroligand Complexes with Ethylenediamine, Diethylenetriamine or N,N,N′,N′,N″-Pentamethyldiethylene Triamine in Aqueous Solution

Solution equilibrium studies on Cu2+–L1–L2 ternary systems have been performed by pH-potentiometry, UV–Vis spectrophotometry and EPR methods {where L1 corresponds to a polyamine such as ethylenediamine (en), diethylenetriamine (dien), N,N,N′,N′,N″-pentamethyldiethylenetriamine (Me5dien)} and L2 denotes 2-aminoethylphosphonic acid (β-alaninephosphonic acid)}. The results suggest the formation of heteroligand complexes with [Cu(L1)(β-Ala(P))] stoichiometry in all of the studied systems. Additionally, in the system with en, [Cu(en)(β-Ala(P))H−1]− is formed in basic solutions. Our spectroscopic results indicate tetragonal geometry for the [Cu(en)(β-Ala(P))] species, a geometry slightly deviated from square pyramidal for the [Cu(dien)(β-Ala(P))] complex, and somewhat stronger geometry distortion was present for the [Cu(Me5dien)(β-Ala(P))] complex. The coordination modes in these heteroligand complexes are discussed.

Relative binding affinity of carboxylate-, phosphonate-, and bisphosphonate-functionalized gold nanoparticles targeted to damaged bone tissue

Functionalized Au NPs have received considerable recent interest for targeting and labeling cells and tissues. Damaged bone tissue can be targeted by functionalizing Au NPs with molecules exhibiting affinity for calcium. Therefore, the relative binding affinity of Au NPs surface functionalized with either carboxylate (l-glutamic acid), phosphonate (2-aminoethylphosphonic acid), or bisphosphonate (alendronate) was investigated for targeted labeling of damaged bone tissue in vitro. Targeted labeling of damaged bone tissue was qualitatively verified by visual observation and backscattered electron microscopy, and quantitatively measured by the surface density of Au NPs using field-emission scanning electron microscopy. The surface density of functionalized Au NPs was significantly greater within damaged tissue compared to undamaged tissue for each functional group. Bisphosphonate-functionalized Au NPs exhibited a greater surface density labeling damaged tissue compared to glutamic acid- and phosphonic acid-functionalized Au NPs, which was consistent with the results of previous work comparing the binding affinity of the same functionalized Au NPs to synthetic hydroxyapatite crystals. Targeted labeling was enabled not only by the functional groups but also by the colloidal stability in solution. Functionalized Au NPs were stabilized by the presence of the functional groups, and were shown to remain well dispersed in ionic (phosphate buffered saline) and serum (fetal bovine serum) solutions for up to 1 week. Therefore, the results of this study suggest that bisphosphonate-functionalized Au NPs have potential for targeted delivery to damaged bone tissue in vitro and provide motivation for in vivo investigation.

PhnY and PhnZ Comprise a New Oxidative Pathway for Enzymatic Cleavage of a Carbon–Phosphorus Bond

The sequential activities of PhnY, an α-ketoglutarate/Fe(II)-dependent dioxygenase, and PhnZ, a Fe(II)-dependent enzyme of the histidine-aspartate motif hydrolase family, cleave the carbon-phosphorus bond of the organophosphonate natural product 2-aminoethylphosphonic acid. PhnY adds a hydroxyl group to the α-carbon, yielding 2-amino-1-hydroxyethylphosphonic acid, which is oxidatively converted by PhnZ to inorganic phosphate and glycine. The PhnZ reaction represents a new enzyme mechanism for metabolic cleavage of a carbon-phosphorus bond.

A group of glycosphingolipids found in an invertebrate: Their structures and biological significance

A novel group of glycosphingolipids was identified in the nervous tissue and skin of the mollusc, Aplysia kurodai, which lacks gangliosides. More than 30 glycolipids were detected on HPTLC plates and the structures of 9 major glycolipids were determined. They were pentaosylglycosphingolipids and their common core structure was GalNAcα1→3Galβ1→4Glcβ1→1ceramide, except for one glycolipid in which Galβ of the core structure was replaced by Galα. 3-O-MeGalβ or 4-O-MeGlcNAcα or 3,4-O-carboxyethylideneGalβ was at their non-reducing ends. Galα or Fucα binds to Gal of the core structure at 2C as a side chain sugar. One to three 2-aminoethylphosphonic acids and/or phosphoethanolamine link to the glycolipids. Immunohistochemically, glycolipids having carboxyethylideneGal at their non-reducing ends were localized exclusively in nerve bundles. Glycolipids activated cAMP-dependent protein kinase in the rat brain and may directly activate cAMP-dependent protein kinase in a manner similar, but not identical, to that of cAMP. The biological functions of glycolipids may share neurobiological functions proposed for gangliosides in vertebrates.

Binding affinity of surface functionalized gold nanoparticles to hydroxyapatite

Gold nanoparticles (Au NPs) have been investigated for a number of biomedical applications, including drug and gene delivery vehicles, thermal ablation therapy, diagnostic sensors, and imaging contrast agents. Surface functionalization with molecular groups exhibiting calcium affinity can enable targeted delivery of Au NPs to calcified tissue, including damaged bone tissue. Therefore, the objective of this study was to investigate the binding affinity of functionalized Au NPs for targeted delivery to bone mineral, using hydroxyapatite (HA) crystals as a synthetic analog in vitro. Au NPs were synthesized to a mean particle size of 10-15 nm and surface functionalized with either L-glutamic acid, 2-aminoethylphosphonic acid, or alendronate, which exhibit a primary amine for binding gold opposite carboxylate, phosphonate, or bisphosphonate groups, respectively, for targeting calcium. Bisphosphonate functionalized Au NPs exhibited the most rapid binding kinetics and greatest binding affinity to HA, followed by glutamic acid and phosphonic acid. All functional groups reached complete binding after 24 h. Equilibrium binding constants in de-ionized water, determined by nonlinear regression of Langmuir isotherms, were 3.40, 0.69, and 0.25 mg/L for bisphosphonate, carboxylate, and phosphonate functionalized Au NPs, respectively. Functionalized Au NPs exhibited lower overall binding in fetal bovine serum compared to de-ionized water, but relative differences between functional groups were similar.

Phosphonoacetate biosynthesis: In vitro detection of a novel NADP+-dependent phosphonoacetaldehyde-oxidizing activity in cell-extracts of a marine Roseobacter

A novel phosphonoacetaldehyde-oxidizing activity was detected in cell-extracts of the marine bacterium Roseovarius nubinhibens ISM grown on 2-aminoethylphosphonic acid (2-AEP; ciliatine). Extracts also contained 2-AEP transaminase and phosphonoacetate hydrolase activities. These findings indicate the existence of a biological route from 2-AEP via phosphonoacetaldehyde for the production of phosphonoacetate, which has not previously been shown to be a natural product. The three enzymes appear to constitute a previously-unreported pathway for the mineralization of 2-AEP which is a potentially important source of phosphorus in the nutrient-stressed marine environment.