Relationship between protonation and ion condensation for branched poly(ethylenimine)

Nagaya, Jiro; Homma, Masahiro; Tanioka, Akihiko; Minakata, Akira

doi:10.1016/0301-4622(95)00143-3

Cited by 66 publications

(57 citation statements)

References 34 publications

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“…S2), indicating that BPEI played an effective template role for the formation of the BPEI-CuNCs. As nitrogen atoms of BPEI had different degree of protonation on the various pH [35,36], the coordination between BPEI and Cu 2+ ions varied at different pH medias. Under acidic conditions, BPEI was protonated and H + effectively competed with Cu 2+ for binding with amine groups.…”

Section: Characterization Of the Bpei-cuncsmentioning

confidence: 98%

Polyethyleneimine-templated copper nanoclusters via ascorbic acid reduction approach as ferric ion sensor

Feng

Liu

et al. 2015

Analytica Chimica Acta

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Section: Characterization Of the Bpei-cuncsmentioning

confidence: 98%

Polyethyleneimine-templated copper nanoclusters via ascorbic acid reduction approach as ferric ion sensor

Feng

Liu

et al. 2015

Analytica Chimica Acta

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“…Many studies of gene delivery with PEI use the value of PEI protonation provided by titrations of branched PEI performed by Suh et al in 1994,7 who found that only 10–20% of PEI amine groups are protonated at physiological pH (~7.4). Nagaya et al8 reported that approximately 30% of branched PEI amines are protonated at pH 7.4, while others9, 10 have reported chain length dependent pK a ’s for a series of PEI samples in the range of 8.2 to 9.5, indicating that most PEI amine would be protonated at physiological pH. One recent review article11 on non-viral based gene delivery cited that linear PEI has 90% amines protonated at pH~7.…”

Section: Introductionmentioning

confidence: 99%

Understanding the Protonation Behavior of Linear Polyethylenimine in Solutions through Monte Carlo Simulations

2009

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The success of polyethyleneimine (PEI) as a non-viral based gene delivery vector has been attributed to its proton buffering capacity. Despite the great interest in PEI for its use in non-viral based gene delivery, the protonation behavior of PEI in solution is not well understood. Earlier experimental studies have reported inconsistent values of the protonation state of PEI. In this work, we report our investigation of the protonation behavior of a realistic linear PEI (lPEI) with computational approaches. Reported experimental pKa values of several diamine compounds are first examined. A screened coulombic interaction with a distance dependence dielectric is shown to reproduce the shifted pKa values of the model diamine compounds. Then atomistic molecular dynamics simulations of lPEI chain with 20 repeating units are performed and the results are used to provide parameters for a coarse-grained polyamine model. The screened coulombic interaction is then incorporated in the coarse-grained lPEI chain and computational titrations are performed. The obtained computational titration curves of lPEI in solutions were found to be in best agreement with experimental results by Smits et al, but the computational titration curves have too strong of a dependence on salt concentration compared to the experimental results by Smits et al. Disregarding the discrepancy in the salt dependence, our computational titrations reveal that approximately 55% of the lPEI amine groups are protonated under physiological conditions in solution with a nearly alternating arrangement of protonated and non-protonated amines. Titrations of lPEI in the presence of a polyanion are also performed to determine how the charge state of lPEI could be affected by complexation with DNA in gene therapy preparations. While the presence of the polyanion increases the degree of protonation of the PEI, many of PEI amines remain unprotonated under physiological conditions, providing evidence that PEI complexed with DNA could still have proton buffering capacity. Potential sources of error that have resulted in the inconsistency of previously reported protonation states of PEI were also discussed.

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“…Owing to their high charges, BPEI and phytate can be considered as model molecules for the study of the interactions between natural polycations and polyanions. The problems that can be encountered in such a study are connected to the interpretation/elaboration of the experimental data; different methods were used to explain the acid-base properties of BPEI: by applying the Ising model to short-range interactions [29], by relating the BPEI protonation with ion condensation [30] and by calculating the deprotonation quotient at different pHs [31]. In our previous work [23], we used a new approach to study the acid-base properties of BPEI; using this approach the branched poly(ethylenimine) was treated as a simple aliphatic tetramine.…”

Section: Accepted Manuscriptmentioning

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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Relationship between protonation and ion condensation for branched poly(ethylenimine)

Cited by 66 publications

References 34 publications

Polyethyleneimine-templated copper nanoclusters via ascorbic acid reduction approach as ferric ion sensor

Polyethyleneimine-templated copper nanoclusters via ascorbic acid reduction approach as ferric ion sensor

Understanding the Protonation Behavior of Linear Polyethylenimine in Solutions through Monte Carlo Simulations

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

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