Rapid detection of bacterial endotoxins in ophthalmic viscosurgical device materials by direct analysis in real time mass spectrometry

Abstract

Bacterial endotoxins are lipopolysaccharides bound to the bacterial cell wall and released when bacteria rupture or disintegrate. Possible contamination of endotoxin in ophthalmic devices can cause a painful eye inflammation or result in toxic anterior segment syndrome after cataract surgery. Measurement of bacterial endotoxin in medical device materials is difficult since endotoxin binds with polymer matrix and some of the materials are very viscous and non-water soluble, where traditional enzyme-based Limulus amebocyte lysate (LAL) assay cannot be applied. Here we propose a rapid and high throughput ambient ionization mass spectrometric (MS) method using direct analysis in real time (DART) for the evaluation of endotoxin contamination in medical device materials. Large and structurally complex endotoxin instantaneously breaks down into low-mass characteristic fragment ions using DART and is detected by MS in both positive and negative ion modes. This method enables the identification and separation of endotoxin from medical materials with a detection limit of 0.03 ng mL−1 endotoxins in aqueous solution. Ophthalmic viscosurgical device materials including sodium hyaluronate (NaHA), non-water soluble perfluoro-n-octane (PFO) and silicone oil (SO) were spiked with different known concentrations of endotoxin and analyzed by DART MS, where the presence of endotoxin was successfully detected and featured small mass fragment ions were generated for NaHA, PFO and SO as well. Current findings showed the feasibility of measuring endotoxin contamination in medical device materials using DART-MS, which can lead to a one-step analysis of endotoxins in different matrices, avoiding any potential contamination during sample pre-treatment steps.

Novel SH-SAW Biosensors for Ultra-Fast Recognition of Growth Factors

“…There are a lot of methods to measure biomolecules, such as sensitive detection of deoxyribonucleic acid [ 10 ], grow factors [ 11 ], and cells [ 12 ]. Many of them have been used to detect them for a long time to the present, such as those based on fluorometry, spectrophotometry, or chemiluminescence [ 13 ], localized surface plasmon resonance (LSPR) [ 14 ], mass spectrometry [ 15 ], optical methods [ 16 ], the electronic tongue [ 17 ], the voltammetric method [ 18 ], and electrochemistry [ 19 ]. Almost all of them have showed great disadvantages such as: high costs, long operating times, and use of labeled molecules.…”

An aptamer-based shear horizontal surface acoustic wave biosensor with a CVD-grown single-layered graphene film for high-sensitivity detection of a label-free endotoxin

“…Endotoxins are responsible for the toxic effects that cause fevers, 1 septic shock, 2 and sepsis. 3,4 Biosensor based endotoxin detection has been widely investigated recently, 5,6 and many methods have been investigated to identify endotoxins: hydrophobic interactions, 7 localized surface plasmon resonance (LSPR), 8 mass spectrometry, 9 optical methods, 10 the electronic tongue, 11 the voltammetric method, 12 and electrochemistry. [13][14][15][16][17] However, these methods have some disadvantages, such as high costs, a long processing time and the requirement of labeled markers.…”

Direct Analysis in Real Time Mass Spectrometry for Characterization of Large Saccharides

“…Interestingly, a couple of studies have shown that large glycosaminoglycan and lipopolysaccharide can break down into small fragments instantaneously in DART source. 40,41 Nemes et al reported that heparin and its infamous adulterant, oversulfated chondroitin sulfate, can be differentiated through the characteristic small products (m/z < 300) obtained with DART-MS. 40 It is also shown in the literature that large endotoxin molecules can be broken into small fragments (m/z < 450) in the DART source in seconds, and the fragments provide the basis for rapid detection of bacterial endotoxin contamination in medical materials. 41 In the present study, six traditional Chinese herbal medicines, Dendrobium of f icinale (DO), D. nobile (DN), Codonopsis pilosula (CP), Astragalus membranaceus (AM), Poria cocos (PC), and Lentinus edodes (LE) were used to test the potential of using DART-MS-based method for the molecular level characterization of polysaccharides.…”

“…40,41 Nemes et al reported that heparin and its infamous adulterant, oversulfated chondroitin sulfate, can be differentiated through the characteristic small products (m/z < 300) obtained with DART-MS. 40 It is also shown in the literature that large endotoxin molecules can be broken into small fragments (m/z < 450) in the DART source in seconds, and the fragments provide the basis for rapid detection of bacterial endotoxin contamination in medical materials. 41 In the present study, six traditional Chinese herbal medicines, Dendrobium of f icinale (DO), D. nobile (DN), Codonopsis pilosula (CP), Astragalus membranaceus (AM), Poria cocos (PC), and Lentinus edodes (LE) were used to test the potential of using DART-MS-based method for the molecular level characterization of polysaccharides. As a result, DART coupled to high resolution MS produced characteristic fragment ions (m/z < 350) for different types of plant polysaccharides within seconds, providing limit of detection (LOD) ranging from 0.01 to 0.1 ng mL −1 in aqueous solution.…”