Mesoporous silica coated spicules for photodynamic therapy of metastatic melanoma.

We report on the fabrication of mesoporous silicon dioxide coated Haliclona sp. spicules (mSHS) to enhance the delivery of the insoluble photosensitizer protoporphyrin IX (PpIX) into deep skin layers and mediate photodynamic therapy for metastatic melanoma in mice. The mSHS are dispersed sharp edged and rod-like micro-particles with a length of approximate 143.6 ± 6.4 µm and a specific surface area of 14.9 ± 3.4 m2/g. The mSHS can be topically applied to the skin, adapting to any desired skin area and lesion site. The insoluble PpIX were incorporated into the mesoporous silica coating layers of mSHS (mSHS@PpIX) with the maximum PpIX loading capacity of 120.3 ± 3.8 µg/mg. The mSHS@PpIX significantly enhanced the deposition of PpIX in the viable epidermis (5.1 ± 0.4 µg/cm2) and in the dermis (0.5 ± 0.2 µg/cm2), which was 154 ± 11-fold and 22 ± tenfold higher than those achieved by SHS, respectively. Topical delivery of PpIX using mSHS (mSHS@PpIX) completely eradicated the primary melanoma in mice in 10 days without recurrence or metastasis over 60 days. These results demonstrate that mSHS can be a promising topical drug delivery platform for the treatment of diverse cutaneous diseases, such as metastatic melanoma.

Compact Spatial Heterodyne Spectrographs for Future Space-Based Observations: Instrument Modeling and Applications.

High-resolution spectroscopy employing spatial heterodyne spectrographs (SHS) holds significant promise for forthcoming space missions, building upon its established track record in science applications. Notably, it offers exceptional performance and cost- effectiveness in the ultraviolet-visual (UV-Vis) region compared to contemporary instruments. SHS instruments provide high-resolution capabilities and substantially larger etendues than similar resolving power instruments. This study introduces a comprehensive Python-based SHS model integrated with a user-friendly web scraping interface for target star selection, parameter generation, and 2D interferogram creation. Our SHS model demonstrates double the resolving power of a grating spectrometer and a throughput comparable to a Fourier transform spectrometer (FTS) but without moving parts, enhancing robustness for deployment in space. The interferogram processing algorithm includes flat-fielding, bias removal, apodization, and an inverse Fourier transform (IFT) for accurate spectrum retrieval. Despite bandwidth limitations due to resolving power constraints, SHS models excel in applications requiring high spectral resolution over narrow wavelength ranges, such as studying isotopic emission lines. The model provides optimization results and trade-offs for system parameters, ensuring precise spectral recovery with realistic signal-to-noise ratio (SNR) values. SHS is versatile and effective for various scientific applications, including investigating atomic and molecular emissions from comets, planetary atmospheres, the Earth's atmosphere, the Sun, and the interstellar medium (ISM). This research significantly contributes to expediting the development and deployment of SHS instruments, demonstrating their potential across numerous scientific domains.

Trajectories of health-related quality of life and fatigue during vedolizumab therapy in inflammatory bowel disease.

BACKGROUND AND AIM: Normalizing health-related quality of life (QoL) and fatigue are important long-term treatment targets in inflammatory bowel disease (IBD). We examined their evolution in relation to changes in disease activity during vedolizumab therapy. METHODS: Cohort study of biologically refractory IBD patients treated with vedolizumab. Patients were prospectively evaluated at all infusions by Short Health Scale (SHS) (QoL questionnaire covering four health dimensions) (n = 79), visual analogous scale for fatigue (VAS-F) (n = 30), and clinical disease activity. Objective disease assessment was carried out after 1 year or at treatment failure. RESULTS: Patients in steroid-free clinical remission at end of induction improved significantly in all SHS items already from week 2 with full implementation by week 14 ("Symptoms" 59% improvement, P < 0.001; "Function" 63%, P < 0.001; "Worries" 59%, P < 0.001; "Well-being" 40%, P < 0.01). Then, SHS remained stable at background levels (< 20) for 1 year (improvements 67%; 65%; 62%; 57%; P < 0.001). Combined clinical-objective remission at 1 year was associated with highest SHS improvements (64-72%; P < 0.001). Of note, early SHS improvements preceded manifestation of clinical remission in most patients (22 of 33; 67%). Clinical response materialized into late (week 6 or later) and minor SHS improvements (31-46%, P < 0.001). Fatigue improved steadily over 6 months to background levels (VAS-F < 4) among patients in clinical remission (45% decrease) or clinical-objective remission (41%). SHS and VAS-F impairment remained elevated in patients without effect of therapy. CONCLUSION: QoL rapidly improves and predicts later significant clinical-objective efficacies of vedolizumab at end of induction and 1 year. Fatigue improves slowly after remission is attained.

Quality of life and outcomes after rubber band ligation for haemorrhoidal disease.

PURPOSE: The main objective of this study was to assess the impact on quality of life after rubber band ligation (RBL) in patients with symptomatic grade II-III haemorrhoids who did not improve after 6 months of conservative treatment, using quality of life scores. METHODS: This was a prospective cohort observational study where patients with haemorrhoidal disease and indication for RBL were included between December 2019 and December 2020. RBL was offered as first-line treatment in this group. Patient´s quality of life was assessed by scores: HDSS (Hemorrhoidal Disease Symptom Score) and SHS (Short Health Scale).Secondary objectives were: to evaluate the rate of patients requiring one or more RBL procedures, to establish the overall success rate of RBL and to analyse complications. RESULTS: A total of 100 patients were finally included. Regarding the impact on quality of life after RBL, a significant reduction was found in the HDSS and SHS scores (p < 0.001). The main improvement was found in the first month and it was maintained until the sixth month. A high degree of satisfaction with the procedure was reported by 76% of patients. The overall success rate of banding was 89%. A 12% complication rate was detected, the most frequent complication was severe anal pain (58.3%) and self-limiting bleeding (41.7%). CONCLUSION: Rubber band ligation, as a treatment for symptomatic grade II-III haemorrhoids that do not respond to medical treatment, leads to a significant improvement in patients' symptoms and quality of life. It also has a high degree of satisfaction between patients.

Inflammatory Cytokine Elaboration Following Secondhand Smoke (SHS) Exposure Is Mediated in Part by RAGE Signaling.

The receptor for advanced glycation end products (RAGE) is a key contributor to immune and inflammatory responses in myriad diseases. RAGE is a transmembrane pattern recognition receptor with a special interest in pulmonary anomalies due to its naturally abundant pulmonary expression. Our previous studies demonstrated an inflammatory role for RAGE following acute 30-day exposure to secondhand smoke (SHS), wherein immune cell diapedesis and cytokine/chemokine secretion were accentuated in part via RAGE signaling. However, the chronic inflammatory mechanisms associated with RAGE have yet to be fully elucidated. In this study, we address the impact of long-term SHS exposure on RAGE signaling. RAGE knockout (RKO) and wild-type (WT) mice were exposed to SHS using a nose-only delivery system (Scireq Scientific, Montreal, Canada) for six months. SHS-exposed animals were compared to mice exposed to room air (RA) only. Immunoblotting was used to assess the phospho-AKT and phospho-ERK activation data, and colorimetric high-throughput assays were used to measure NF-kB. Ras activation was measured via ELISAs. Bronchoalveolar lavage fluid (BALF) cellularity was quantified, and a mouse cytokine antibody array was used to screen the secreted cytokines. The phospho-AKT level was decreased, while those of phospho-ERK, NF-kB, and Ras were elevated in both groups of SHS-exposed mice, with the RKO + SHS-exposed mice demonstrating significantly decreased levels of each intermediate compared to those of the WT + SHS-exposed mice. The BALF contained increased levels of diverse pro-inflammatory cytokines in the SHS-exposed WT mice, and diminished secretion was detected in the SHS-exposed RKO mice. These results validate the role for RAGE in the mediation of chronic pulmonary inflammatory responses and suggest ERK signaling as a likely pathway that perpetuates RAGE-dependent inflammation. Additional characterization of RAGE-mediated pulmonary responses to prolonged exposure will provide a valuable insight into the cellular mechanisms of lung diseases such as chronic obstructive pulmonary disease.

Volatile organic compounds from second-hand smoke may increase susceptibility of children through oxidative stress damage.

Although humans are generally exposed to second-hand smoke (SHS), volatile organic compounds (VOCs) exposure derived from SHS and its health hazard to non-smokers are rarely investigated. Thus, we examined the effects of SHS on VOCs exposure and oxidative stress damage via a passive smoking simulation experiment in 6 children and 7 adults. To further validate the studied urinary VOC metabolites as biomarkers for passive smoking, 259 children were recruited. The levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG), malonaldehyde (MDA), trans-3'-hydroxycotinine (OH-Cot) and 31 VOC metabolites in urine were determined. The results showed that the geomean concentrations of 17 VOC metabolites in urine of children were 26.5%-138% higher than those of adults after passive smoking. The levels of urinary 8-OHdG, MDA and OH-Cot increased by 24.6%, 18.8% and 600% in children, but only 1.25%, 10.3% and 116% in adults, respectively. Therefore, children are more vulnerable to SHS than adults. After exposure to SHS, the levels of 8 urinary VOC metabolites of benzene, acrylonitrile, 1-bromopropane, propylene oxide, toluene, methyl methacrylate and cyanide increased by 60.9%-538% within 23 h. These 8 VOC metabolites were also significantly associated with 8-OHdG or MDA in urine (p < 0.01). Therefore, exposure to VOCs caused by SHS increases body oxidative stress damage. OH-Cot level higher than 2.00 µg/g Cr can be used as a threshold of passive smoking. The levels of urinary s-benzylmercapturic acid (BMA) and s-phenylmercapturic acid (PMA) in children increased by 494% and 728% within 6 h after passive smoking, respectively. Population validation study indicated that BMA and PMA levels were significantly elevated in children exposed to SHS. Therefore, in addition to OH-Cot, urinary BMA and PMA are potentially useful short-term biomarkers of passive smoking. Future studies should focus on the differences in VOC metabolism and detoxification mechanisms between children and adults.

Review on factors affecting coffee volatiles: from seed to cup.

The objective of this review is to evaluate the influence of six factors on coffee volatiles. At present, the poor aroma from robusta or low-quality arabica coffee can be significantly improved by advanced technology, and this subject will continue to be further studied. On the other hand, inoculating various starter cultures in green coffee beans has become a popular research direction for promoting coffee aroma and flavor. Several surveys have indicated that shade and altitude can affect the content of coffee aroma precursors and volatile organic compounds (VOCs), which remain to be fully elucidated. The emergence of the new roasting process has greatly enriched the aroma composition of coffee. Cold-brew coffee is one of the most popular trends in coffee extraction currently, and its influence on coffee aroma is worthy of in-depth and detailed study. Omics technology will be one of the most important means to analyze coffee aroma components and their quality formation mechanism. A better understanding of the effect of each parameter on VOCs would assist coffee researchers and producers in the optimal selection of post-harvest parameters that favor the continuous production of flavorful and top-class coffee beans and beverages. © 2021 Society of Chemical Industry.

Urinary biomarkers for secondhand smoke and heated tobacco products exposure.

Concerns have recently grown about the health effects of secondhand smoke exposure and heated tobacco products. The analysis of tobacco smoke biomarkers is critical to assess the health effects of tobacco smoke exposure. For this purpose, the simultaneous determinations of exposure markers and health effect markers would provide a better evaluation of smoke exposure. In this study, nicotine metabolites (nicotine, cotinine, trans-3'-hydroxycotinine) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol in urine were analyzed as exposure markers. The DNA damage markers, 7-methylguanine and 8-hydroxy-2'-deoxyguanosine, were simultaneously measured as health effect markers. The results revealed significant levels of urinary nicotine metabolites and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol in the subjects exposed to secondhand smoke and heated tobacco products. In addition, the urinary levels of 7-methylguanine and 8-hydroxy-2'-deoxyguanosine tended to be high for secondhand smoke and heated tobacco products exposures, as compared to those of non-smokers. These biomarkers will be useful for evaluating tobacco smoke exposure.

The impact of implementation of a national smoke-free prisons policy on indoor air quality: results from the Tobacco in Prisons study.

OBJECTIVE: To determine secondhand smoke (SHS) concentrations in prisons during the week of implementation of a new, national prisons smoke-free policy. DESIGN: Repeated measurement of SHS concentrations immediately before and after implementation of smoke-free policies across all 15 prisons in Scotland, and comparison with previously gathered baseline data from 2016. METHODS: Fine particulate matter (PM2.5) measurements at a fixed location over a continuous 6-day period were undertaken at the same site in each prison as previously carried out in 2016. Outdoor air quality data from the nearest local authority measurement station were acquired to determine the contribution of outdoor air pollution to indoor prison measurement of PM2.5. RESULTS: Air quality improved in all prisons comparing 2016 data with the first full working day postimplementation (overall median reduction -81%, IQR -76% to -91%). Postimplementation indoor PM2.5 concentrations were broadly comparable with outdoor concentrations suggesting minimal smoking activity during the period of measurement. CONCLUSIONS: This is the first evaluation of changes in SHS concentrations across all prisons within a country that has introduced nationwide prohibition of smoking in prisons. All prisons demonstrated immediate substantial reductions in PM2.5 following policy implementation. A smoke-free prisons policy reduces the exposure of prison staff and prisoners to SHS.

The effect of prenatal smoke exposure on child neuropsychological function: a prospective mother-child cohort study.

Objective: To study prospectively the effect of prenatal smoke exposure (PSE) on child neuropsychological function and intelligence quotient (IQ).Background: PSE has been associated with adverse effects on child neurodevelopment. However, some studies reported that these associations disappear after adjustment for potential confounders.Methods: A cohortof 248 mothers-child dyad was followed from the first trimester of pregnancy until children were 7.5 years old. PSE was recorded during pregnancy by questionnaire and plasma cotinine. The Wechsler Intelligence Scale for Children, the Neuropsychological Assessment of Executive Functions for Children (ENFEN) and the School Neuropsychological Maturity Questionnaire were administered at 7.5 years of age. The effect of PSE on child IQ and neuropsychological function was assessed with ANCOVA, adjusting for obstetric, neonatal and sociodemographic factors.Results: Children whose mothers smoked throughout pregnancy scored lower in interference (ENFEN) compared to unexposed children (F = 4.1; p = .008). The results showed no differences in other executive functions, verbal and visual memory and IQ between the PSE groups.Conclusion: PSE had little effect on child neuropsychological outcome and was limited to mental flexibility. Nevertheless, these findings support further efforts aimed at encouraging mothers to quit smoking in pregnancy.

Evaluation of Long-Term Performance of a Solar Home System (SHS) Monitoring System on Harsh Environments.

Dataloggers installed in rural regions of developing countries need to be autonomous, robust, and have good recording capacity as they may be exposed to harsh environmental conditions. An extremely hot, dry, and dusty climate can imply additional wear and tear toequipment. A test procedurewas designed and run in a confined space to control climate conditions to test the datalogger. An outdoor campaign lasting more than three years was performed at the Instituto Madrileño de Estudios Avanzados (IMDEA) Water Institute, in Alcalá de Henares (Madrid, Spain) and at the Escuela Politécnica Superior (EPS) Linares (Jaén, Spain) to test the low-cost datalogger under real conditions. The results demonstrated that it was robust and endured extreme weather conditions. In order to avoid the loss of data, a new version with a redundant system based on an SD card was implemented and tested under real conditions.

Highly selective catalytic reduction of NOx by MnOx-CeO2-Al2O3 catalysts prepared by self-propagating high-temperature synthesis.

We first present preparation of MnOx-CeO2-Al2O3 catalysts with varying Mn contents through a self-propagating high-temperature synthesis (SHS) method, and studied the application of these catalysts to the selective catalytic reduction of NOx with NH3 (NH3-SCR). Using the catalyst with 18 wt.% Mn (18MnCe1Al2), 100% NO conversion was achieved at 200°C and a gas hourly space velocity of 15384hr-1, and the high-efficiency SCR temperature window, where NO conversion is greater than 90%, was widened to a temperature range of 150-300°C. 18MnCe1Al2 showed great resistance to SO2 (100 ppm) and H2O (5%) at 200°C. The catalysts were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller (BET) analysis, scanning electron microscopy, Fourier transform infrared spectroscopy, and H2 temperature programmed reduction. The characterization results showed that the surface atomic concentration of Mn increased with increasing Mn content, which led to synergism between Mn and Ce and improved the activity in the SCR reaction. 18MnCe1Al2 has an extensive pore structure, with a BET surface area of approximately 135.4m2/g, a pore volume of approximately 0.16cm3/g, and an average pore diameter of approximately 4.6 nm. The SCR reaction on 18MnCe1Al2 mainly followed the Eley-Rideal mechanism. The performances of the MnOx-CeO2-Al2O3 catalysts were good, and because of the simplicity of the preparation process, the SHS method is applicable to their industrial-scale manufacture.

Frontal Cortex Proteome Perturbation after Juvenile Rat Secondhand Smoke Exposure.

Secondhand smoke remains a global concern for children's health. Epidemiological studies implicate exposure to secondhand smoke as a major risk factor for behavioral disorders, yet biological causation remains unclear. Model studies have mainly focused on secondhand smoke impacts to prenatal neurodevelopment, yet juvenile exposure represents a separate risk. Using ion mobility-enhanced data-independent mass spectrometry, the effect of juvenile secondhand smoke exposure on the prefrontal cortex, a principal part of the brain involved in behavioral control, is characterized. The produced dataset includes 800 significantly responsive proteins within the juvenile orbital frontal cortex, with 716 showing an increase in abundance. The neuroproteomic response reflects a prominent perturbation within the glutamatergic synaptic system, suggesting aberrant, disorganized excitation as observed underlying psychiatric disorders. Also disclosed are impacts to GABAergic and dopaminergic systems. Overall, the dataset provides a wealth of detail, facilitating further targeted research into the causal mechanisms underlying behavioral disorders associated with juvenile exposure to secondhand smoke and other environmental pollutants. All MS data have been deposited to the ProteomeXchange consortium with identifier PXD011744.

Research on a Visual Electronic Nose System Based on Spatial Heterodyne Spectrometer.

Light absorption gas sensing technology has the characteristics of massive parallelism, cross-sensitivity and extensive responsiveness, which make it suitable for the sensing task of an electronic nose (e-nose). With the performance of hyperspectral resolution, spatial heterodyne spectrometer (SHS) can present absorption spectra of the gas in the form of a two dimensional (2D) interferogram which facilitates the analysis of gases with mature image processing techniques. Therefore, a visual e-nose system based on SHS was proposed. Firstly, a theoretical model of the visual e-nose system was constructed and its visual maps were obtained by an experiment. Then the local binary pattern (LBP) and Gray-Level Co-occurrence Matrix (GLCM) were used for feature extraction. Finally, classification algorithms based on distance similarity (Correlation coefficient (CC); Euclidean distance to centroids (EDC)) were chosen to carry on pattern recognition analysis to verify the feasibility of the visual e-nose system.

A Rotational Gyroscope with a Water-Film Bearing Based on Magnetic Self-Restoring Effect.

Stable rotor levitation is a challenge for rotational gyroscopes (magnetically suspended gyroscopes (MSG) and electrostatically suspended gyroscopes (ESG)) with a ring- or disk-shaped rotor, which restricts further improvement of gyroscope performance. In addition, complicated pick-up circuits and feedback control electronics propose high requirement on fabrication technology. In the proposed gyroscope, a ball-disk shaped rotor is supported by a water-film bearing, formed by centrifugal force to deionized water at the cavity of the lower supporting pillar. Water-film bearing provides stable mechanical support, without the need for complicated electronics and control system for rotor suspension. To decrease sliding friction between the rotor ball and the water-film bearing, a supherhydrophobic surface (SHS) with nano-structures is fabricated on the rotor ball, resulting in a rated spinning speed increase of 12.4% (under the same driving current). Rotor is actuated by the driving scheme of brushless direct current motor (BLDCM). Interaction between the magnetized rotor and the magnetic-conducted stator produces a sinusoidal rotor restoring torque, amplitude of which is proportional to the rotor deflection angle inherently. Utilization of this magnetic restoring effect avoids adding of a high amplitude voltage for electrostatic feedback, which may cause air breakdown. Two differential capacitance pairs are utilized to measure input angular speeds at perpendicular directions of the rotor plane. The bias stability of the fabricated gyroscope is as low as 0.5°/h.

The Self-sustained High temperature Synthesis (SHS) technology as novel approach in the management of asbestos waste.

The SHS technique was experimented in chrysotile breakdown. By means of two reactions such as Mg3Si2O5(OH)4 + Fe2O3 + 3 Mg and 2Mg3Si2O5(OH)4 + Fe3O4 + 4 Mg the chrysotile was completely converted into forsterite-rich olivine. Different mixtures of hematite + Mg and magnetite + Mg were tested with chrysotile to establish the maximum chrysotile amount in order to allow the reaction. In comparison with conventional thermal treatments, the SHS process is characterized by a fast reaction, needs low activation energy and the apparatus is simple. For these reasons, the asbestos neutralisation is carried out with positive balance of time and costs of the process. Furthermore, the combustion product can be re-used as secondary material.

Identification of Volatile Compounds and Selection of Discriminant Markers for Elephant Dung Coffee Using Static Headspace Gas Chromatography-Mass Spectrometry and Chemometrics.

Elephant dung coffee (Black Ivory Coffee) is a unique Thai coffee produced from Arabica coffee cherries consumed by Asian elephants and collected from their feces. In this work, elephant dung coffee and controls were analyzed using static headspace gas chromatography hyphenated with mass spectrometry (SHS GC-MS), and chemometric approaches were applied for multivariate analysis and the selection of marker compounds that are characteristic of the coffee. Seventy-eight volatile compounds belonging to 13 chemical classes were tentatively identified, including six alcohols, five aldehydes, one carboxylic acid, three esters, 17 furans, one furanone, 13 ketones, two oxazoles, four phenolic compounds, 14 pyrazines, one pyridine, eight pyrroles and three sulfur-containing compounds. Moreover, four potential discriminant markers of elephant dung coffee, including 3-methyl-1-butanol, 2-methyl-1-butanol, 2-furfurylfuran and 3-penten-2-one were established. The proposed method may be useful for elephant dung coffee authentication and quality control.

Bioinspired Surfaces with Superwettability for Anti-Icing and Ice-Phobic Application: Concept, Mechanism, and Design.

Ice accumulation poses a series of severe issues in daily life. Inspired by the nature, superwettability surfaces have attracted great interests from fundamental research to anti-icing and ice-phobic applications. Here, recently published literature about the mechanism of ice prevention is reviewed, with a focus on the anti-icing and ice-phobic mechanisms, encompassing the behavior of condensate microdrops on the surface, wetting, ice nucleation, and freezing. Then, a detailed account of the innovative fabrication and fundamental research of anti-icing materials with special wettability is summarized with a focus on recent progresses including low-surface energy coatings and liquid-infused layered coatings. Finally, special attention is paid to a discussion about advantages and disadvantages of the technologies, as well as factors that affect the anti-icing and ice-phobic efficiency. Outlooks and the challenges for future development of the anti-icing and ice-phobic technology are presented and discussed.

Identification of terpenes and essential oils by means of static headspace gas chromatography-ion mobility spectrometry.

Static headspace gas chromatography-ion mobility spectrometry (SHS GC-IMS) is a relatively new analytical technique that has considerable potential for analysis of volatile organic compounds (VOCs). In this study, SHS GC-IMS was used for the identification of the major terpene components of various essential oils (EOs). Based on the data obtained from 25 terpene standards and 50 EOs, a database for fingerprint identification of characteristic terpenes and EOs was generated utilizing SHS GC-IMS for authenticity testing of fragrances in foods, cosmetics, and personal care products. This database contains specific normalized IMS drift times and GC retention indices for 50 terpene components of EOs. Initially, the SHS GC-IMS parameters, e.g., drift gas and carrier gas flow rates, drift tube, and column temperatures, were evaluated to determine suitable operating conditions for terpene separation and identification. Gas chromatography-mass spectrometry (GC-MS) was used as a reference method for the identification of terpenes in EOs. The fingerprint pattern based on the normalized IMS drift times and retention indices of 50 terpenes is presented for 50 EOs. The applicability of the method was proven on examples of ten commercially available food, cosmetic, and personal care product samples. The results confirm the suitability of SHS GC-IMS as a powerful analytical technique for direct identification of terpene components in solid and liquid samples without any pretreatment. Graphical abstract Fingerprint pattern identification of terpenes and essential oils using static headspace gas chromatography-ion mobility spectrometry.

Analysis of Listeria using exogenous volatile organic compound metabolites and their detection by static headspace-multi-capillary column-gas chromatography-ion mobility spectrometry (SHS-MCC-GC-IMS).

Listeria monocytogenes is a Gram-positive bacterium and an opportunistic food-borne pathogen which poses significant risk to the immune-compromised and pregnant due to the increased likelihood of acquiring infection and potential transmission of infection to the unborn child. Conventional methods of analysis suffer from either long turn-around times or lack the ability to discriminate between Listeria spp. reliably. This paper investigates an alternative method of detecting Listeria spp. using two novel enzyme substrates that liberate exogenous volatile organic compounds in the presence of α-mannosidase and D-alanyl aminopeptidase. The discriminating capabilities of this approach for identifying L. monocytogenes from other species of Listeria are investigated. The liberated volatile organic compounds (VOCs) are detected using an automated analytical technique based on static headspace-multi-capillary column-gas chromatography-ion mobility spectrometry (SHS-MCC-GC-IMS). The results obtained by SHS-MCC-GC-IMS are compared with those obtained by the more conventional analytical technique of headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). The results found that it was possible to differentiate between L. monocytogenes and L. ivanovii, based on their VOC response from α-mannosidase activity.