Tandem mass spectrometric analysis of novel peptide‐modified gemini surfactants used as gene delivery vectors

Abstract

Diquaternary ammonium gemini surfactants have emerged as effective gene delivery vectors. A novel series of 11 peptide-modified compounds was synthesized, showing promising results in delivering genetic materials. The purpose of this work is to elucidate the tandem mass spectrometric (MS/MS) dissociation behavior of these novel molecules establishing a generalized MS/MS fingerprint. Exact mass measurements were achieved using a hybrid quadrupole orthogonal time-of-flight mass spectrometer, and a multi-stage MS/MS analysis was conducted using a triple quadrupole-linear ion trap mass spectrometer. Both instruments were operated in the positive ionization mode and are equipped with electrospray ionization. Abundant triply charged [M+H] species were observed in the single-stage analysis of all the evaluated compounds with mass accuracies of less than 8 ppm in mass error. MS/MS analysis showed that the evaluated gemini surfactants exhibited peptide-related dissociation characteristics because of the presence of amino acids within the compounds' spacer region. In particular, diagnostic product ions were originated from the neutral loss of ammonia from the amino acids' side chain resulting in the formation of pipecolic acid at the N-terminus part of the gemini surfactants. In addition, a charge-directed amide bond cleavage was initiated by the amino acids' side chain producing a protonated α-amino-ε-caprolactam ion and its complimentary C-terminus ion that contains quaternary amines. MS/MS and MS analysis revealed common fragmentation behavior among all tested compounds, resulting in the production of a universal MS/MS fragmentation pathway. Copyright © 2017 John Wiley & Sons, Ltd.

Mass Spectrometric Detection and Characterization of Metabolites of Gemini Surfactants Used as Gene Delivery Vectors

“…Subsequent dealkylation of this ion, by losing the spacer group with its attached amino acid, results in the formation of the product ion at m/z 270.3153 (Figure a). This fragmentation pattern is consistent with what was previously obtained via collision induced dissociation (CID) on a Q-LIT instrument . In a similar manner, the deuterated gemini surfactant 16-7N­(GK)-16-D 4 produced characteristic product ions with the expected mass shift of 2.0136 Da at m/z 287.2389, 278.7767, 270.3151, and 270.2637 (Figure S8a in Supporting Information).…”

“…This fragmentation pattern is consistent with what was previously obtained via collision induced dissociation (CID) on a Q-LIT instrument. 28 In a similar manner, the deuterated gemini surfactant 16-7N(GK)- The metabolite M-a was proposed to be an acetylation product of 16-7N(GK)-16, with an accurate mass at m/z 432.4238, corresponding to N-acetylation (42.0106 Da) of the original structure. However, the precise location of substitution on the lysine could not be determined (shown for illustration on the lysine side chain), as the acetylation products with both primary amines generate the same characteristic product ions.…”

Establishment of the tandem mass spectrometric fingerprints of taxane‐based anticancer compounds

“…MS/MS analysis confirms the molecular structures of tested compounds and helps in identifying diagnostic product ions that can be used for qualitative and quantitative analyses. For example, CID‐MS/MS analysis of a series of diquaternary ammonium gemini surfactants, used as gene‐delivery systems, was first established 17–19 . Subsequently, multiple reaction monitoring (MRM) MS‐based methods were successfully developed to determine gemini surfactants in biological samples 20–22 .…”

Tandem mass spectrometric analysis of novel caffeine scaffold‐based bifunctional compounds for Parkinson's disease

“…In addition, CID‐MS/MS analysis allows for the selection of diagnostic quantifier and qualifier ions for the development of multiple reaction monitoring (MRM) quantitative methods. For instance, a generalized MS/MS fingerprint was developed for a series of structurally similar novel drug delivery agents, namely gemini surfactants . Subsequently, the established CID‐MS/MS fingerprint was used to develop a targeted MS method for the quantification of these compounds within cellular lysate …”

“…For instance, a generalized MS/MS fingerprint was developed for a series of structurally similar novel drug delivery agents, namely gemini surfactants. [25][26][27] Subsequently, the established CID-MS/MS fingerprint was used to develop a targeted MS method for the quantification of these compounds within cellular lysate. [28][29][30] In this present study, we evaluated the CID-MS/MS fragmentation behavior of three novel bifunctional compounds, which were designed as potential diagnostics or therapeutics for PD.…”