Absolute quantification of poly( dl -lactide- co -glycolide) in microspheres using quantitative 1 H NMR spectroscopy

Zhang, Qi; Guo, Ningzi; Sun, Yue; Li, Xiaodong; Hua-xin, Yang

doi:10.1016/j.jpba.2017.08.046

Cited by 10 publications

(7 citation statements)

References 25 publications

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“…Despite the high interest in PLGA, a convenient method for the quantification of the polymer matrix is still lacking. Usually, the PLGA system is estimated by gravimetric methods after sample lyophilization or, for increasing the sensitivity, by more complex methods like mass spectrometry, nuclear magnetic resonance or other analysis methods [13], [14], [15], [16], [17]. However, these approaches suffer partly from sensitivity, as the pure polymer matrix cannot be quantified selectively or the required equipment for improving the sensitivity is expensive and the quantification is time consuming.…”

Section: Introductionmentioning

confidence: 99%

Development of a fast and precise method for simultaneous quantification of the PLGA monomers lactic and glycolic acid by HPLC

Pourasghar

Koenneke

Meiers

et al. 2019

Journal of Pharmaceutical Analysis

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Poly(lactide- co -glycolide acid) (PLGA) is an extraordinary well-described polymer and has excellent pharmaceutical properties like high biocompatibility and good biodegradability. Hence, it is one of the most used materials for drug delivery and biomedical systems, also being present in several US Food and Drug Administration-approved carrier systems and therapeutic devices. For both applications, the quantification of the polymer is inalienable. During the development of a production process, parameters like yield or loading efficacy are essential to be determined. Although PLGA is a well-defined biomaterial, it still lacks a sensitive and convenient quantification approach for PLGA-based systems. Thus, we present a novel method for the fast and precise quantification of PLGA by RP-HPLC. The polymer is hydrolyzed into its monomers, glycolic acid and lactic acid. Afterwards, the monomers are derivatized with the absorption-enhancing molecule 2,4′-dibromoacetophenone. Furthermore, the wavelength of the derivatized monomers is shifted to higher wavelengths, where the used solvents show a lower absorption, increasing the sensitivity and detectability. The developed method has a detection limit of 0.1 µg/mL, enabling the quantification of low amounts of PLGA. By quantifying both monomers separately, information about the PLGA monomer ratio can be also directly obtained, being relevant for degradation behavior. Compared to existing approaches, like gravimetric or nuclear magnetic resonance measurements, which are tedious or expensive, the developed method is fast, ideal for routine screening, and it is selective since no stabilizer or excipient is interfering. Due to the high sensitivity and rapidity of the method, it is suitable for both laboratory and industrial uses.

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Section: Introductionmentioning

confidence: 99%

Development of a fast and precise method for simultaneous quantification of the PLGA monomers lactic and glycolic acid by HPLC

Pourasghar

Koenneke

Meiers

et al. 2019

Journal of Pharmaceutical Analysis

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“…Small amounts of acetic acid from the synthesis are visible at 1.9 ppm. In the spectrum of the electrospun PLGA fibers (Figure 4B) there is a signal at $1.5 ppm which we attribute to the CH 3 groups of lactic acid, the signals at 5.2 and 4.8 ppm are assigned to the CH of lactic acid and CH 2 from glycolic acid, respectively 18,43. These characteristic peaks confirm the chemical integrity of the PLGA copolymer after the electrospinning process.…”

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confidence: 58%

“…Characteristic resonances appear also at 2995, 2946, and 1454 cm −1 and were assigned to CH 2 , CH 3 and CH stretching vibrations of the functional groups of PLGA 18‐20 . In the IR spectrum of the TSC there is a signal at 779 cm −1 attributed to the CS stretching 43 . Moreover, there is a sharp signal at 1517 cm −1 due to CN vibration band and the absorption at 3359 cm −1 assigned to NH stretching vibrations in TSC 9,44,45 (for a spectrum of the TSC, see Figure S3).…”

Section: Resultsmentioning

confidence: 99%

“…[18][19][20] In the IR spectrum of the TSC there is a signal at 779 cm −1 attributed to the C S stretching. 43 Moreover, there is a sharp signal at 1517 cm −1 due to C N vibration band and the absorption at 3359 cm −1 assigned to N H stretching vibrations in TSC 9,44,45 (for a spectrum of the TSC, see Figure S3). There is a resonance at 1520 cm −1 in the PLGA-TSC fibers, which we attribute to the C N vibration of TSC.…”

Section: Resultsmentioning

confidence: 99%

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Sustained release of a thiosemicarbazone from antibacterial electrospun poly(lactic‐co‐glycolic acid) fiber mats

Barani

Haseloer

Mathur

et al. 2020

Polymers for Advanced Techs

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Antibacterial fiber mats of poly(lactic-co-glycolic acid) (PLGA) were produced in the presence of different amounts of the thiosemicarbazone (TSC) N4-(S)-(1-phenylethyl)-2-(pyridin-2-ylmethylene)hydrazine-1-carbothioamide (HfpyTSCmB) through electrospinning. Increasing amounts (0, 2.5, 5, and 10 wt%) of TSC in the PLGA spinning solution in 2,2,2-trifluoroethanol (TFE) caused an increase up to 230% in conductivity and up to 27% in viscosity. The morphology of the electrospun fibers was studied using scanning electron microscope (SEM) and showed the formation of uniform, bead free, cylindrical, and smooth fiber mats. Increasing amounts of HfpyTSCmB in the polymer solution resulted also in significant shrinking of the diameter and narrowing of the size distribution of the fibers in line with the increased conductivity of the spinning solutions. Nuclear magnetic resonance (NMR) spectroscopy and thermal methods (DSC and TG/DTA) gave proof for the chemical integrity of HfpyTSCmB in the fiber mats after the electrospinning process. The release profile of HfpyTSCmB from the fibers was examined using UV-vis absorption spectroscopy. The observed release data during 21 days was fitted to different mathematical models with the best results obtained from the Higuchi release model. The fiber mat samples showed effective antibacterial properties with inhibition zones of 0.5 to 1.5 mm against the Gram-positive Staphylococcus aureus and the Gram-negative Escherichia coli. K E Y W O R D S bacteriostatic properties, controlled drug release, nano fiber mats, PLGA, thiosemicarbazone 1 | INTRODUCTION There is an increasing demand for novel antimicrobial materials in many application areas, due to threatening human health with the growth of drug-resistant pathogens due to the biological and morphological modifications. This has led the high demand for novel drugs with enhanced, targeted activity. Thiosemicarbazones (TSC) are very promising molecules having interesting pharmacological properties with remarkable antioxidant, antiviral, antibacterial, anticancer, antitumor, antimalarial, ribonucleotide reductase enzyme inhibition, and antifungal activities when coordinated to metals but also in their absence. 1-7 TSC are synthesized through condensation of thiosemicarbazides with aldehydes or ketones. 1-3 The source thiosemicarbazides are synthesized either from secondary amines in a substitution reaction with methyl hydrazinecarbodithioate or from the addition of hydrazine to isothiocyanates. 6-13 TSC can act as ligands coordinating metal ions through their azomethine nitrogen and thiocarbonyl sulfur atoms (Scheme 1). The title TSC N4-(S)-(1-phenylethyl)-2-(pyridin-2-ylmethylene)hydrazine-1-carbothioamide (HfpyTSCmB) potentially coordinates metals through three (NNS)

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“…1 H NMR has conjointly been applied as a quantitative analytical tool for the quantification owing to the fact that the signal intensity in 1 H NMR corresponds directly to the number of proton nuclei responsible for that signal (Rizzo and Pinciroli, 2005). Quantitative 1 H NMR (qHNMR) has emerged as an effective analytical tool for quality analysis in various fields such as natural drugs (Yan et al, 2016), food, and beverages (Cao et al, 2014), PLGA‐based microspheres (Zhang et al, 2017), medicinal components (Göğer et al, 1999; Hollis, 1963), and dietary supplements (Phansalkar et al, 2017). Apart from qHNMR, HPLC and GC are widely used chromatographic techniques for the quantification of the molecules (Gelbard et al, 1995).…”

Section: Introductionmentioning

confidence: 99%

Proton Nuclear Magnetic Resonance‐Based Method for the Quantification of Epoxidized Methyl Oleate

Kaur

Bhardwaj

Kaur

et al. 2020

J Americ Oil Chem Soc

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Epoxidized methyl esters (EMO) with their high oxirane ring reactivity, acts as a raw material in the synthesis of various industrial chemicals including polymers, stabilizers, plasticizers, glycols, polyols, carbonyl compounds, biolubricants etc. EMO has been generally quantified by the gas chromatography (GC) and high‐performance liquid chromatography (HPLC) techniques. Taking into the account of the limitations of these techniques, two qHNMR‐based equations have been proposed for the quantification of EMO in the mixture of EMO and methylesters (MO). The validity of the proposed method was determined using standard mixtures of MO and EMO having different molar concentrations. The developed equations have been applied on the samples of EMO prepared from oleic acid in two‐step process viz., esterification followed by epoxidation. The qHNMR‐based EMO quantification showed acceptable agreement with the results obtained from HPLC analysis.

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Absolute quantification of poly( dl -lactide- co -glycolide) in microspheres using quantitative 1 H NMR spectroscopy

Cited by 10 publications

References 25 publications

Development of a fast and precise method for simultaneous quantification of the PLGA monomers lactic and glycolic acid by HPLC

Development of a fast and precise method for simultaneous quantification of the PLGA monomers lactic and glycolic acid by HPLC

Sustained release of a thiosemicarbazone from antibacterial electrospun poly(lactic‐co‐glycolic acid) fiber mats

Proton Nuclear Magnetic Resonance‐Based Method for the Quantification of Epoxidized Methyl Oleate

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