Application of a Simple Three-Parameter Model to Titration Data for Some Linear Polyelectrolytes.

Högfeldt, Erik; Miyajima, Tohru; Marinsky, Jacob A.; Muhammed, Mamoun; Ruiz, José Manuel Medina; Colacio, Enrique; Mulichak, A. M.; Alminger, Tomas; Erickson, Magnus; Grundevik, Inger; Hagin, Inger; Hoffman, Kurt-Jürgen; Johansson, Svante; Larsson, Sam; Löfberg, Ingalil; Ohlson, Kristina; Persson, Björn; Skånberg, Inger; Tekenbergs-Hjelte, Lija

doi:10.3891/acta.chem.scand.43-0496

Cited by 55 publications

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“…2). The different binding capacity at both pH values is explained by the dissociation constants of the PAA reported in the literature; pK a,1 =4.8-5.4, and pK a,2 =6.5-7.5 extrapolated to I=0 M at 25°C for PAA with molecular weights from 2 to 750 kDa (Katchalsky 1954;Hogfeldt et al 1989;de Stefano et al 2000de Stefano et al , 2003David et al 2008;Crea et al 2009;de Stefano et al 2010). Accordingly with these values the largest dissociation degree of the PAA, and, therefore, the largest binding capacity for Cd would be expected at pH 8.5.…”

Section: Qd-only Effect Of Phmentioning

confidence: 99%

Stability of core/shell quantum dots—role of pH and small organic ligands

Domingos¹,

Franco²,

Pinheiro

2013

Environ Sci Pollut Res

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The improvement of knowledge about the toxicity and even processability, and stability of quantum dots (QD) requires the understanding of the relationship between the QD binding head group, surface structure, and interligand interaction. The scanned stripping chronopotentiometry and absence of gradients and Nernstian equilibrium stripping techniques were used to determine the concentration of Cd dissolved from a polyacrylate-stabilized CdTe/ CdS QD. The effects of various concentrations of small organic ligands such as citric acid, glycine, and histidine and the roles of pH (4.5-8.5) and exposure time (0-48 h) were evaluated. The highest QD dissolution was obtained at the more acidic pH in absence of the ligands (52 %) a result of the CdS shell solubility. At pH 8.5 the largest PAA ability to complex the dissolved Cd leads to a further QD solubility until the equilibrium is reached (24 % of dissolved Cd vs. 4 % at pH 6.0). The citric acid presence resulted in greater QD dissolution, whereas glycine, an amino acid, acts against QD dissolution. Surprisingly, the presence of histidine, an amino acid with an imidazole functional group, leads to the formation of much strong Cd complexes over time, which may be non-labile, inducing variations in the local environment of the QD surface.

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Section: Qd-only Effect Of Phmentioning

confidence: 99%

Stability of core/shell quantum dots—role of pH and small organic ligands

Domingos¹,

Franco²,

Pinheiro

2013

Environ Sci Pollut Res

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“…[37][38][39] Naime, osim ponekad izrazito dobrog slaganja izračunatih i eksperimentalno određenih prividnih konstanti deprotonacije, spomenuti načini obrade omogućuju procjenu intrinzičkih pK-vrijednosti.…”

Section: -45unclassified

“…Pored opisanog načina obrade protonske ravnoteže linearnih polikiselina nerijetko se primjenjuju i semiempirijske jednadžbe poput jednadžbe Katchalskog, 36 Högfeldta, [37][38][39] odnosno Mandela. 20 Katchalsky za ovisnost prividnih, koncentracijskih konstanti ravnoteže protonacije predlaže sljedeći izraz:…”

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Protonacijske ravnoteže linearnih homopolikiselina

Požar

2015

Kem. Ind.

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Prirodoslovno-matematički fakultet, Sveučilište u Zagrebu Horvatovac 102a, Zagreb Sažetak U radu je dan sažet pregled dosadašnjih istraživanja termodinamike protonacije linearnih homopolikiselina, posebice onih visoke gustoće naboja. Pored prikaza eksperimentalnih rezultata koji se mogu naći u literaturi, u radu su opisani i teorijski modeli za obradu ovisnosti protonacijskih konstanti ravnoteže o stupnju disocijacije monomera, odnosno o ionskoj jakosti (cilindrični model temeljen na Poisson-Boltzmannovoj jednadžbi, Sternov cilindrični model, Isingov model, Högfeldtov model, Mandelov model i model Katchalskoga). Primjenjivost navedenih modela za opis protonacijske ravnoteže linearnih homopolikiselina razmatrana je s obzirom na gustoću naboja poliiona, koncentraciju dodanog elektrolita i vrstu protuiona koji kompenziraju naboj makroiona. Ukratko su prikazani i rezultati Monte Carlo simulacija protonacijske ravnoteže. Dodatno, dan je osvrt na česte pogreške vezane uz baždarenje elektrokemijskih članaka prilikom određivanja specijacije polikiselina u otopinama. Polimer, polielektrolit, homopolikiselina, protonacija, protuioni * Dr. sc. Josip Požar e-pošta: pozar@chem.pmf.hr J. POŽAR: Protonacijske ravnoteže linearnih homopolikiselina, Kem. Ind. 64 (7-8) (2015) 353−362 354 suprotnog naboja i mogućnost adsorpcije navedenih spojeva na suprotno nabijene koloidne čestice preduvjet su za izgradnju složenih nanokompozita postupkom sukcesivne adsorpcije makroiona na podlogu od oksida metala, odnosno polumetala. Navedenu činjenicu prvi je prepoznao G. Decher. Godine 1991. sukcesivnom adsorpcijom linearnih sintetskih polielektrolita suprotnoga naboja na pločicu od silicijeva dioksida priredio je prvi polielektrolitni višesloj. 10 Od tada do današnjih dana priređeni su mnogobrojni višeslojevi izgrađeni u pravilu od najmanje jednog polielektrolita visoke gustoće naboja i različitih električki nabijenih makromolekula (proteini, sintetski i prirodni poliioni različite gustoće naboja), odnosno koloidnih čestica s iznimnim fizikalno-kemijskim svojstvima. Ključne riječi10-12 U novije vrijeme polielektrolitni višeslojevi zaokupili su velik broj istraživača zbog mogućnosti njihove praktične primjene u biotehnologiji 13,14 i biomedicini, 15 ali i industriji. 11 U tijeku su i istraživanja biokompatibilnosti višeslojeva 11 i polielektrolitnih kapsula 16 poradi mogućnosti njihove upotrebe za ciljanu dostavu manjih molekula i lijekova u tkiva zahvaće-na tumorom ili nekom drugom bolesti. Primjerice, zamijećeno je da se mnoge molekule mogu ugraditi u višeslojeve iz kojih se potom postupno otpuštaju. Čak je moguća i ugradnja enzima u višeslojeve bez gubitka njihove aktivnosti.11,17 Štoviše, neki su se enzimi u višeslojevima pokazali aktivnijima nego u otopini.17 Razumljivo, istraživanja više-slojeva intenzivirala su i istraživanja interpolielektrolitne neutralizacije u otopinama, odnosno protonacijske ravnoteže polikiselina i polibaza. Međutim, za razliku od istraži-vanja interpolielektrolitne neutralizacije, istraživanja protonacijske r...

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“…For the determination of high molecular weight polyelectrolytes protonation constants [6 and references therein], the dependence of log K H on the degree of protonation (or on the degree of ionisation) must be taken into account; this implies the use of different calculation methods [38][39]. Nevertheless, in a previous work [23], a simple new approach to calculate the protonation constants, and enthalpy changes, of BPEI was proposed.…”

Section: Protonation Constantsmentioning

confidence: 99%

Sequestering ability of phytate towards protonated BPEI and other polyammonium cations in aqueous solution

Crea

Stefano

Porcino

et al. 2008

Biophysical Chemistry

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Please cite this article as: Francesco Crea, Concetta De Stefano, Nunziatina Porcino, Silvio Sammartano, Sequestering ability of phytate towards protonated BPEI and other polyammonium cations in aqueous solution, Biophysical Chemistry (2008Chemistry ( ), doi: 10.1016Chemistry ( /j.bpc.2008 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT AbstractThe interaction between protonated branched poly(ethylenimine) [BPEI] and phytate (1,2,3,4,5,6 hexakis (di-hydrogen phosphate) myo-inositol) [Phy] was studied potentiometrically. The measurements were carried out at t = 25 °C and at low ionic strength values, without addition of supporting electrolyte, to avoid interferences with other anions and cations. In order to simplify the data treatment, BPEI was considered as a simple tetramine. Different species Phy(BPEI)H j , with j = 6,7,8, and Phy(BPEI) 2 H 7 were found, having quite high stability. The ability of phytate to sequester BPEI was quantified by considering the parameter pL 50 , namely the concentration (-log [Phy] tot ) necessary to bind 50% of polyammonium cation (as trace). In our experimental conditions, for the system phytate-BPEI-proton we have pL 50 = 7.01, at pH = 7.4 and I = 0.04 mol L -1 . As for other phytate-polyammonium cation systems, the stability of the phytate-BPEI species is strictly proportional to the charges involved in the formation reactions. Therefore, it was possible to calculate the free energy contribution per bond, 0 b G Δ = 4.4±0.4 kJ mol -1 . The dependence on temperature and ionic strength of the stability of phytate-low/high molecular weight polyammonium cations species, was studied using some semiempirical equations and enthalpy data for the protonation of both components. The dependence on temperature of the stability is quite low and the variation of pL 50 in the range 15 ≤ t/°C ≤ 37 is less than 0.5 log units. On the contrary, the effect of ionic strength is highly significant, with a lowering of pL 50 of ≈ 2 log units (I = 0 to 0.15 mol L -1 ).

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Application of a Simple Three-Parameter Model to Titration Data for Some Linear Polyelectrolytes.

Cited by 55 publications

References 0 publications

Stability of core/shell quantum dots—role of pH and small organic ligands

Stability of core/shell quantum dots—role of pH and small organic ligands

Protonacijske ravnoteže linearnih homopolikiselina

Sequestering ability of phytate towards protonated BPEI and other polyammonium cations in aqueous solution

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