Raman spectroscopic analysis of the interaction between squaric acid and dimethylsulfoxide

Georgopoulos, Stéfanos Leite; Edwards, Howell G. M.; Oliveira, Luiz Fernando Cappa de

doi:10.1016/j.saa.2013.03.052

Cited by 15 publications

(18 citation statements)

References 41 publications

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“…Squaric acid was first synthesized by Cohen, et al in 1959 [40] and is currently the most popular cyclic oxocarbon acid. It is typically used as a bioorganic and medicinal compound formed by organic synthetic chemistry [40][41][42][43][44]. Squaric acid is a strong diacid that exhibits two acidic hydroxyl groups with pKa values of 0.5 and 3.5 [42].…”

Section: Introductionmentioning

confidence: 99%

Fabrication of Anodic Porous Alumina by Squaric Acid Anodizing

Kikuchi¹,

Yamamoto²,

Natsui³

et al. 2014

Electrochimica Acta

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The growth behavior of anodic porous alumina formed via anodizing in a new electrolyte, squaric acid (3,4-dihydroxy-3-cyclobutene-1,2-dione), is reported for the first time. A high-purity aluminum foil was anodized in a 0.1 M squaric acid solution at 293 K and a constant applied potential of 100-150 V. Anodic oxides grew on the aluminum foil at applied potentials of 100-120 V, but a burned oxide film was formed at higher voltage. Anodic porous alumina with a cell size of approximately 200-400 nm and sub-100-nm-scale pore diameter was successfully fabricated by anodizing in squaric acid. The cell size of the anodic oxide increased with anodizing time because of the uneven growth of the porous layer. The anodic porous alumina obtained by squaric acid anodizing consists of amorphous Al 2 O 3 containing 5-6 at% carbon from the electrolyte. Fig. 1). The morphology of anodic porous alumina, especially its cell size (identical meaning to interpore distance) and pore diameter in the porous layer, is limited by the electrolyte and voltage (electrochemical potential) applied during anodizing [23,24]. Fig. 1 summarizes the anodizing electrolytes that have been reported to date for porous alumina fabrication. Sulfuric (H 2 SO 4 ), oxalic ((COOH) 2 ), and phosphoric (H 3 PO 4 ) acids are well-known, self-ordering anodizing solutions for porous alumina fabrication, and highly ordered porous alumina can be obtained by anodizing in these solutions at constant voltages of 18-25 V, 40 V, and 160-195 V, respectively [24-29]. Malonic acid (HOOC-CH 2 -COOH) and tartaric acid (HOOC-(CHOH) 2 -COOH), typical dicarboxylic acids, have also been reported to support the fabrication of highly ordered porous alumina fabrication at 120 V and 195 V, respectively [30,31]. In addition, several other electrolytes, such as chromic (H 2 CrO 4 ) [32,33], malic (HOOC-CH(OH)-CH 2 -COOH) [23,34], citric (HOCO-CH 2 -C(OH)(COOH)-COOH)) [23], and glycolic (CH 2 OH-COOH) [23] acids, have been reported as anodizing electrolytes to date. However, the formation of thick porous alumina with straight nanopores by anodizing in chromic acid is difficult because of branching and colony-forming nanopores [35]. Although citric acid anodizing has already been used for nanostructure fabrication [36], other organic electrolytes, including malic and glycolic acid solutions, cause the formation of non-uniform anodic porous alumina [23,34]. Therefore, five self-ordering electrolytes, namely, sulfuric, oxalic, and phosphoric acids, are generally selected for anodic porous alumina fabrication by many researchers.In recent years, new anodizing procedures using an effective experimental approach and optimal anodizing conditions have been reported by several researchers to control the nano-scale features of anodic porous alumina. Lee et al. studied the rapid formation of ordered porous alumina by a hard anodizing procedure involving a powerful cooling stage and obtained an ultra-high aspect ratio (>1,000) of anodic porous alumina by anodizing in oxalic acid at 120-150...

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Section: Introductionmentioning

confidence: 99%

Fabrication of Anodic Porous Alumina by Squaric Acid Anodizing

Kikuchi¹,

Yamamoto²,

Natsui³

et al. 2014

Electrochimica Acta

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“…As shown in Fig. 3, spectrum a, FTIR spectrum of SA shows absorption bands at about 2214 cm −1 , 1812 cm −1 , and 1643 cm −1 , which were ascribed to hydrogen bonding, carbonyl groups, and C--C bonds, respectively (Cohen et al, 1959;Feder, 1980;Baglin & Rose, 1970;Georgopoulos et al, 2013). The broad band at 1512 cm −1 with a slight shoulder at 1544 cm −1 is due to the C--O stretching vibration.…”

Section: Resultsmentioning

confidence: 86%

“…The dianion of squaric acid is absolutely symmetrical as the negative charges are equally distributed between each oxygen atom. Squaric acid represents a new class of aromatic substances, which is supported by the vibrational spectra of C 4 O 2− 4 (Cohen et al, 1959;Feder, 1980;Baglin & Rose, 1970;Georgopoulos et al, 2013;West & Powell, 1963).…”

Section: Introductionmentioning

confidence: 99%

Stable UV absorption material synthesized by intercalation of squaric acid anion into layered double hydroxides

Shen

Zhang

et al. 2015

Chemical Papers

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A novel UV absorption material of squaric acid (SA) anion (C4O 2− 4 ) intercalated layered double hydroxides (LDHs) was successfully synthesized by the co-precipitation method. After intercalation, the interlayer distance of MgAl-SA-LDHs increased to 1.04 nm compared to those of MgAl-CO3-LDHs and SA anions present in form of a monolayer in the interlayer of LDHs. Thermal stability of SA clearly enhanced by the intercalation and the suppression of the deintercalation ability of MgAl-SA-LDHs was superior to that of 4-hydroxy-3-methoxybenzoic acid intercalated LDHs. The results of UV-DRS indicate the potential application of MgAl-SA-LDHs as UV absorbers.

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“…The bioreducible poly- l -lysine (bPLL) was obtained by oxidation of the CKKKKKC monomer (30 mg) by DMSO (200 µL) in PBS (700 µL) for 5 d, followed by purification by dialyzing against water at 4 °C (3.5 kDa cutoff) and freeze-drying. Successful preparation of the desired product was confirmed by 1 H NMR [ 47 ] and Raman spectroscopy (confirming the formation of disulfide bonds, not present in the starting peptide [ 49 , 50 , 51 , 52 , 53 , 54 ]) ( Figure S3 ).…”

Section: Methodsmentioning

confidence: 98%

In Vitro Evaluation of Lipopolyplexes for Gene Transfection: Comparing 2D, 3D and Microdroplet-Enabled Cell Culture

et al. 2020

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Complexes combining nucleic acids with lipids and polymers (lipopolyplexes) show great promise for gene therapy since they enable compositional, physical and functional versatility to be optimized for therapeutic efficiency. When developing lipopolyplexes for gene delivery, one of the first evaluations performed is an in vitro transfection efficiency experiment. Many different in vitro models can be used, and the effect of the model on the experiment outcome has not been thoroughly studied. The objective of this work was to compare the insights obtained from three different in vitro models, as well as the potential limitations associated with each of them. We have prepared a series of lipopolyplex formulations with three different cationic polymers (poly-l-lysine, bioreducible poly-l-lysine and polyethyleneimine), and assessed their in vitro biological performance in 2D monolayer cell culture, 3D spheroid culture and microdroplet-based single-cell culture. Lipopolyplexes from different polymers presented varying degrees of transfection efficiency in all models. The best-performing formulation in 2D culture was the polyethyleneimine lipopolyplex, while lipoplexes prepared with bioreducible poly-l-lysine were the only ones achieving any transfection in microdroplet-enabled cell culture. None of the prepared formulations achieved significant gene transfection in 3D culture. All of the prepared formulations were well tolerated by cells in 2D culture, while at least one formulation (poly-l-lysine polyplex) delayed 3D spheroid growth. These results highlight the need for selecting the appropriate in vitro model depending on the intended application.

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Raman spectroscopic analysis of the interaction between squaric acid and dimethylsulfoxide

Cited by 15 publications

References 41 publications

Fabrication of Anodic Porous Alumina by Squaric Acid Anodizing

Fabrication of Anodic Porous Alumina by Squaric Acid Anodizing

Stable UV absorption material synthesized by intercalation of squaric acid anion into layered double hydroxides

In Vitro Evaluation of Lipopolyplexes for Gene Transfection: Comparing 2D, 3D and Microdroplet-Enabled Cell Culture

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