Papers by Malama Chisanga
Frontiers in Chemistry, 2019
With more than a million seizures of illegal drugs reported annually across Europe, the variety o... more With more than a million seizures of illegal drugs reported annually across Europe, the variety of psychoactive compounds available is vast and ever-growing. The multitude of risks associated with these compounds are well-known and can be life threatening. Hence the need for the development of new analytical techniques and approaches that allow for the rapid, sensitive, and specific quantitative detection and discrimination of such illicit materials, ultimately with portability for field testing, is of paramount importance. The aim of this study was to demonstrate the application of Raman spectroscopy and surface-enhanced Raman scattering (SERS) combined with chemometrics approaches, as rapid and portable techniques for the quantitative detection and discrimination of a wide range of novel psychoactive substances (methcathinone and aminoindane derivatives), both in powder form and in solution. The Raman spectra of the psychoactive compounds provided clear separation and classification of the compounds based on their core chemical structures; viz. methcathinones, aminoindanes, diphenidines, and synthetic cannabinoids. The SERS results also displayed similar clustering patterns, with improved limits of detections down to ∼2 mM (0.41 g L −1). As mephedrone is currently very popular for recreational use we performed multiplexed quantitative detection of mephedrone (4-methylmethcathinone), and its two major metabolites (nor-mephedrone and 4-methylephedrine), as tertiary mixtures in water and healthy human urine. These findings readily illustrate the potential application of SERS for simultaneous detection of multiple NPS as mixtures without the need for lengthy prior chromatographic separation or enrichment methods.
Biophotonics in Point-of-Care II
Sensors & Diagnostics
Monitoring antibody response to SARS-CoV-2 is critical for assessing the humoral response, especi... more Monitoring antibody response to SARS-CoV-2 is critical for assessing the humoral response, especially important considering the emergence of multiple SARS-CoV-2 variants of concern (VOCs). Herein, we developed microfluidics-integrated multiplexed SERS...
Applied spectroscopy, 2018
The microbial world forms a huge family of organisms that exhibit the greatest phylogenetic diver... more The microbial world forms a huge family of organisms that exhibit the greatest phylogenetic diversity on Earth and thus colonize virtually our entire planet. Due to this diversity and subsequent complex interactions, the vast majority of microorganisms are involved in innumerable natural bioprocesses and contribute an absolutely vital role toward the maintenance of life on Earth, whilst a small minority cause various infectious diseases. The ever-increasing demand for environmental monitoring, sustainable ecosystems, food security, and improved healthcare systems drives the continuous search for inexpensive but reproducible, automated and portable techniques for detection of microbial isolates and understanding their interactions for clinical, environmental, and industrial applications and benefits. Surface-enhanced Raman scattering (SERS) is attracting significant attention for the accurate identification, discrimination and characterization and functional assessment of microbial c...
Faraday discussions, Jan 4, 2017
Jürgen Popp opened a general discussion of the paper by Roy Goodacre: What is the advantage of us... more Jürgen Popp opened a general discussion of the paper by Roy Goodacre: What is the advantage of using SERS instead of ordinary Raman spectroscopy? Roy Goodacre replied: Raman and SERS in the context of using stable isotopically labeled substrates to investigate metabolism within the environment are complementary, and we have indeed used Raman and FT-IR in very similar systems. 1 Raman will measure the whole cell and give information on, for example, protein labeling inside the bacteria as seen in shis in the ring vibration in phenylalanine. By contrast, SERS generally provides highly selective and specic information on the cell surface, 2 which is of course the part of the cell in contact with the environment and is therefore sensitive to changes within the immediate area surrounding the cell. Some bacteria are able to reduce metal ions inside the cell 3 and this can be used to probe within the cell as well.
Faraday discussions, Jan 4, 2017
Ashish Tripathi opened a discussion of the paper by Volker Deckert: TERS imaging of the triangula... more Ashish Tripathi opened a discussion of the paper by Volker Deckert: TERS imaging of the triangular shaped nanoparticle with a D3ATP monolayer is shown in Fig. 3 of your paper. 1 The chemical map of the 1438 cm À1 band of the D3ATP monolayer suggests that the signal intensities are higher at the edges than near the centre (Fig. 3, bottom le). Can you comment?
Faraday Discuss.
It is clear that investigating how bacterial cells work by analysing their functional roles in mi... more It is clear that investigating how bacterial cells work by analysing their functional roles in microbial communities is very important in environmental, clinical and industrial microbiology. The benefits of linking genes to their respective functions include the reliable identification of the causative agents of various diseases, which would permit appropriate and timely treatment in healthcare systems. In industrial and municipal wastewater treatment and management, such knowledge may allow for the manipulation of microbial communities, such as through bioaugmentation, in order to improve the efficiency and effectiveness of bioremediation processes. Stable isotope probing coupled with identification techniques has emerged to be a potentially reliable tool for the discrimination, identification and characterization of bacteria at community and single cell levels, knowledge which can be utilized to link microbially mediated bioprocesses to phylogeny. Development of the surface-enhanc...
This dataset contains all the spectra used in "Surface Enhanced Raman Spectroscopy for quant... more This dataset contains all the spectra used in "Surface Enhanced Raman Spectroscopy for quantitative analysis: results of a large-scale European multi-instrument interlaboratory study". Data are available in 2 different formats: - a compressed archive with 1 folder ("Dataset") cointaining all the 3516 TXT files (1 file = 1 spectrum) uploaded by all participants (all spectra of the Interlaboratory study); - 1 single CSV file ("ILSspectra.csv") with all the 3516 spectra uploaded by all participants in the form of a table. The data are structured as follow, with each row being 1 spectrum, preceded by metadata: "labcode", "substrate", "laser", "method", "sample", "type", "conc", "batch", "replica". Note that for those spectra starting after 400 cm-1 and/or ending before 2000 cm-1 missing values were expressed as NAs.
Frontiers in Chemistry, Jun 19, 2019
With more than a million seizures of illegal drugs reported annually across Europe, the variety o... more With more than a million seizures of illegal drugs reported annually across Europe, the variety of psychoactive compounds available is vast and ever-growing. The multitude of risks associated with these compounds are well-known and can be life threatening. Hence the need for the development of new analytical techniques and approaches that allow for the rapid, sensitive, and specific quantitative detection and discrimination of such illicit materials, ultimately with portability for field testing, is of paramount importance. The aim of this study was to demonstrate the application of Raman spectroscopy and surface-enhanced Raman scattering (SERS) combined with chemometrics approaches, as rapid and portable techniques for the quantitative detection and discrimination of a wide range of novel psychoactive substances (methcathinone and aminoindane derivatives), both in powder form and in solution. The Raman spectra of the psychoactive compounds provided clear separation and classification of the compounds based on their core chemical structures; viz. methcathinones, aminoindanes, diphenidines, and synthetic cannabinoids. The SERS results also displayed similar clustering patterns, with improved limits of detections down to ∼2 mM (0.41 g L −1). As mephedrone is currently very popular for recreational use we performed multiplexed quantitative detection of mephedrone (4-methylmethcathinone), and its two major metabolites (nor-mephedrone and 4-methylephedrine), as tertiary mixtures in water and healthy human urine. These findings readily illustrate the potential application of SERS for simultaneous detection of multiple NPS as mixtures without the need for lengthy prior chromatographic separation or enrichment methods.
Analytical Chemistry
Surface-enhanced Raman scattering (SERS) is a powerful and sensitive technique for the detection ... more Surface-enhanced Raman scattering (SERS) is a powerful and sensitive technique for the detection of fingerprint signals of molecules and for the investigation of a series of surface chemical reactions. Many studies introduced quantitative applications of SERS in various fields, and several SERS methods have been implemented for each specific application, ranging in performance characteristics, analytes used, instruments, and analytical matrices. In general, very few methods have been validated according to international guidelines. As a consequence, the application of SERS in highly regulated environments is still considered risky, and the perception of a poorly reproducible and insufficiently robust analytical technique has persistently retarded its routine implementation. Collaborative trials are a type of interlaboratory study (ILS) frequently performed to ascertain the quality of a single analytical method. The idea of an ILS of quantification with SERS arose within the framework of Working Group 1 (WG1) of the EU COST Action BM1401 Raman4Clinics in an effort to overcome the problematic perception of quantitative SERS methods. Here, we report the first interlaboratory SERS study ever conducted, involving 15 laboratories and 44 researchers. In this study, we tried to define a methodology to assess the reproducibility and trueness of a quantitative SERS method and to compare different methods. In our opinion, this is a first important step toward a "standardization" process of SERS protocols, not proposed by a single laboratory but by a larger community.
ABSTRACT: There is no doubt that the contribution of microbially mediated bioprocesses toward mai... more ABSTRACT: There is no doubt that the contribution of microbially mediated bioprocesses toward maintenance of life on earth is vital. However, understanding these microbes in situ is currently a bottleneck, as most methods require culturing these microorganisms to suitable biomass levels so that their phenotype can be measured. The development of new culture-independent strategies such as stable isotope probing (SIP) coupled with molecular biology has been a breakthrough toward linking gene to function, while circumventing in vitro culturing. In this study, for the first time we have combined Raman spectroscopy and Fourier transform infrared (FT-IR) spectroscopy, as metabolic fingerprinting approaches, with SIP to demonstrate the quantitative labeling and differentiation of Escherichia coli cells. E. coli cells were grown in minimal medium with fixed final concentrations of carbon and nitrogen supply, but with different ratios and combinations of 13C/12C glucose and 15N/14N ammonium ...
Applied Sciences
Surface-enhanced Raman scattering (SERS) has recently gained increasing attention for the detecti... more Surface-enhanced Raman scattering (SERS) has recently gained increasing attention for the detection of trace quantities of biomolecules due to its excellent molecular specificity, ultrasensitivity, and quantitative multiplex ability. Specific single or multiple biomarkers in complex biological environments generate strong and distinct SERS spectral signals when they are in the vicinity of optically active nanoparticles (NPs). When multivariate chemometrics are applied to decipher underlying biomarker patterns, SERS provides qualitative and quantitative information on the inherent biochemical composition and properties that may be indicative of healthy or diseased states. Moreover, SERS allows for differentiation among many closely-related causative agents of diseases exhibiting similar symptoms to guide early prescription of appropriate, targeted and individualised therapeutics. This review provides an overview of recent progress made by the application of SERS in the diagnosis of c...
Foodborne disease is a serious and largely preventable public health challenge, specifically desc... more Foodborne disease is a serious and largely preventable public health challenge, specifically described as a global burden. Results from recent WHO estimates show that; 1 in 10 people across the world become ill following the ingestion of contaminated food, 420,000 deaths result from foodborne disease annually, with children below 5 years of age accounting for almost one-third of the total. It is apparent that there is a constant need to develop new methods, as well as refine existing approaches, for the detection and analysis of foodborne bacterial pathogens and food disease outbreaks, especially with the emergence and global threat of antibiotic resistant strains, in order to reduce the burden of foodborne bacteria. Here, in this short overview we offer a brief background introduction to the potential role of omics (genomics, transcriptomics, proteomics, metabolomics, lipidomics) approaches and look at some of the recent research undertaken using these methods for the analysis of s...
Microbial communities play essential functions which drive various ecosystems supporting animal a... more Microbial communities play essential functions which drive various ecosystems supporting animal and aquatic life. However, linking bacteria with specific metabolic functions is difficult, since microbial communities consist of numerous and phylogenetically diverse microbes. Stable isotope probing (SIP) combined with single-cell tools has emerged as a novel culture-independent strategy for unravelling microbial metabolic roles and intertwined interactions in complex communities. In this study, we applied Raman and Fourier-transform infrared (FT-IR) spectroscopies, secondary ion mass spectrometry (SIMS) with SIP to probe the rate of 13C incorporation in Escherichia coli at 37 and 25 °C. Our results indicate quantitative enrichment and flow of 13C into E. coli at various time points. Multivariate and univariate analyses of Raman and FT-IR data demonstrated distinctive 13C concentration-dependent trends that were due to vibrational bands shifting to lower frequencies and these shifts we...
The Analyst
This review compares and contrasts MALDI-MS, FT-IR spectroscopy and Raman spectroscopy for whole ... more This review compares and contrasts MALDI-MS, FT-IR spectroscopy and Raman spectroscopy for whole organism fingerprinting and bacterial typing.
ACS Chemical Biology
Prenylated flavin mononucleotide (prFMN) is a recently discovered modified flavin cofactor contai... more Prenylated flavin mononucleotide (prFMN) is a recently discovered modified flavin cofactor containing an additional nonaromatic ring, connected to the N5 and C6 atoms. This cofactor underpins reversible decarboxylation catalyzed by members of the widespread UbiD enzyme family and is produced by the flavin prenyltransferase UbiX. Oxidative maturation of the UbiX product prFMNH2 to the corresponding oxidized prFMNiminium is required for ferulic acid decarboxylase (Fdc1; a UbiD-type enzyme) activity. However, it is unclear what role the Fdc1 enzyme plays in this process. Here, we demonstrate that, in the absence of Fdc1, prFMNH2 oxidation by O2 proceeds via a transient semiquinone prFMNradical species and culminates in a remarkably stable prFMN-hydroperoxide species. Neither forms of prFMN are able to support Fdc1 activity. Instead, enzyme activation using O2-mediated oxidation requires prFMNH2 binding prior to oxygen exposure, confirming that UbiD enzymes play a role in O2-mediated oxidative maturation. In marked contrast, alternative oxidants such as potassium ferricyanide support prFMNiminium formation both in solution and in Fdc1.
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Papers by Malama Chisanga