La pollution des milieux aquatiques par les métaux lourds demande une évaluation du risque des effets toxiques chez des espèces aquatiques. En particulier, le cadmium est connu pour être un métal non essentiel pour le fonctionnement cellulaire et toxique à faible concentration. Environ 25 000 tonnes de cadmium par année sont rejetées dans l'environnement via les activités industrielles, d'extraction de métaux, par l'emploi de pesticides et autres. Dans ce contexte, tant la formation que l'activité de l'appareil photosynthétique représente une cible importante pour les contaminants métalliques parce que l'inhibition des processus biochimiques et biophysiques de la photosynthèse affectent en entier la physiologie des plantes. Dans cette étude, la biosynthèse de la chlorophylle et la fluorescence chlorophyllienne ont été utilisées afin d'évaluer les effets toxiques du cadmium sur la formation de l'appareil photosynthétique et son activité. Dans un premier temps, l'effet toxique du cadmium a été évalué sur l'activité photosynthétique de l'algue verte. Dans cette partie, la fluorescence chlorophyllienne des algues est utilisée comme une approche pour évaluer le risque de toxicité du cadmium. Une altération de la capacité photosynthétique induite par les métaux lourds se reflète dans le rendement et la cinétique de fluorescence. Deux souches de cette espèce, une souche «sauvage» (CC-125 WT mt+) avec paroi cellulaire et une souche «mutante» (CC-400 CW 15 mt+) sans paroi, ont été employées pour étudier les effets de la paroi cellulaire sur l'absorption du cadmium et son effet toxique après 24 et 48 heures de traitement. Les courbes dose-réponse obtenues pour ces deux souches ont permis d'identifier une grande sensibilité des effets toxiques du cadmium pour les algues sans paroi par rapport à celles avec paroi en présence d'une même concentration nominale de cadmium. Les paramètres photosynthétiques de fluorescence ont indiqués que le site d'inhibition au cadmium a été au complexe enzymatique du dégagement d'oxygène associé au photosystème II. Dans la seconde partie, afin d'évaluer la capacité à synthétiser la chlorophylle dans un environnement contaminé au cadmium, la phototransformation de la protochlorophyllide (PChlide) en chlorophyllide (Chlide) par l'enzyme protochlorophyllide oxydoréductase (POR) a été étudié chez l'algue unicellulaire Chlamydomonas reinhardtii. Une souche mutante ne synthétisant pas la chlorophylle à l'obscurité a du être utilisé afin d'obtenir des cellules étiolées, c'est-à-dire que les chloroplastes de ces cellules ne sont pas encore formés. La fluorescence à basse température (77 °K) est l'outil permettant de suivre dans le temps la phototransformation des pigments et la formation des photosystèmes. Les spectres de fluorescence ont permis d'évaluer un certain retard dans la phototransformation de la protochlorophyllide en chlorophyllide ce qui a une répercussion sur la formation des photosystèmes. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Cadmium, Chlamydomonas reinhardtii, Chlorophillide, Chlorophylle, Cytométrie de flux, Fluorescence, Métaux lourds, NADPH-protochlorophyllide oxydoréductase, Photosynthèse, Protochlorophillide, Toxicité.

Oil from flaxseed (Linum usitatisssimum L.) contains hydrophobic cyclic peptides or cyclolinopeptides (CLs) comprising eight or nine amino acids. These bioactive compounds have potential therapeutic applications and may be used as scaffolds for increased utility. Two steps were undertaken to increase the potential utility of these compounds. Initially multigram quantities of flax CLs were highly enriched from flax oil. Subsequently new synthetic procedures were developed for modification of the CLs through the methionine group (Met). Finally, the utility of the modified CLs was tested in a number of applications. CLs were recovered from a crude oil extract that contain five CLs (CLA, CLC, CLE, CLJ and CLK). Oxidation of this mixture reduced the complexity of the mix to just three CLA, CLJ and CLK. CLJ and CLK were enriched then characterized by NMR and MS-MS methods. CLs containing methionine sulfoxide groups (Mso), CLC and CLE were isolated from crude mixture then selectively reduced to afford Met containing analogs: CLB and CLE'. The Met of modified CLs was used as a point for attachment of tags and couplers for various applications. Cyclic peptide modification through Met groups has not been reported previously. Synthetic methods were devised to introduce activating functional groups such as -CN, -COOH, -OH and -NH2 to the sulfur atom of Met. The modified CL conjugates were characterized using spectrometric techniques including 1D and 2D NMR spectrometry, as well as mass spectrometry. After activation the CLs were covalently linked to molecules or materials of interest including fluorescence tags (coumarin), affinity chromatography media and bovine serum albumin (BSA) for production of polyclonal antibodies. Fluorescence studies were performed in methanol, ethanol, dimethylformamide and acetonitrile to study the solvent effect. CLs attached to solid affinity matrix showed specific binding to apolipoprotein A1 after incubation with chicken serum. These CLs also act as hapten and have been used to couple BSA to produce polyclonal antibodies. Met modification was a satisfactory approach to produce a range of useful peptide products where more conventional methods of molecule attachment are not available.

L'utilisation des nanoparticules (NPs) métalliques en nanotechnologie entraîne un risque de contamination de l'environnement qui est difficile à évaluer en raison du manque de connaissance toxicologique sur les NPs. La compréhension des mécanismes de toxicité des NPs peut favoriser leur utilisation sécuritaire. Dans cette optique, l'objectif principal de cette thèse est de mieux comprendre la toxicité des NPs métalliques. Le premier objectif visait à évaluer les effets des NPs de CuO sur la photosynthèse à l'aide de bioindicateurs basés sur la fluorescence chlorophylienne. Les NPs de CuO encapsulées dans un polymère, modèle des NPs pouvant être libérées des peintures antisalissures, induisent une inhibition de la photosynthèse du macrophyte aquatique Lemna gibba. L'imagerie de fluorescence chlorophyllienne est montrée comme une approche utile pour évaluer la toxicité des NPs. De plus, en utilisant deux approches complémentaires de fluorescence chlorophyllienne, le cuivre ionique et les NPs de CuO ont montré des effets similaires sur l'activité photosynthétique. La solubilisation des NPs de CuO est donc proposée comme principal mécanisme d'action des NPs de CuO sur la photosynthèse. Le deuxième objectif consistait à déterminer comment l'encapsulation dans un polymère modifie la toxicité des NPs. La toxicité de NPs de CuO nues ou encapsulées a été évaluée chez l'algue Chlamydomonas reinhardtii. L'encapsulation augmente la toxicité des NPs encapsulées en augmentant leur pénétration dans la cellule, ce qui indique que la toxicité des NPs de CuO est associée à des interactions intracellulaires. Les mécanismes cellulaires d'action des NPs ont été étudiés chez L. gibba en évaluant la toxicité en relation avec l'accumulation de cuivre dans l'organisme. Cette relation indique que les NPs de CuO nues et encapsulées n'ont pas le même mode d'action au niveau cellulaire. La modification des propriétés de surface des NPs par l'encapsulation modifie le mécanisme d'action cellulaire en augmentant la formation d'espèces réactives de l'oxygène. Les NPs métalliques peuvent donc avoir des mécanismes d'action différents selon leurs propriétés physico-chimiques. Le dernier objectif était de caractériser la toxicité des NPs métalliques chez différents modèles biologiques. Pour les NPs d'or stabilisées par un dendrimère poly(amidoamine) (PAMAM), la toxicité était liée au changement des propriétés physico-chimiques des NPs dans le milieu. Ces NPs étaient toxiques pour l'algue C. reinhardtii et la bactérie Vibrio fischeri alors que les cellules animales Neuro-2A et Vero n'étaient pas affectées. La différence de sensibilité était liée à l'altération des propriétés des NPs dans le milieu, soulignant ainsi le besoin de caractériser les NPs dans le milieu utilisé pour évaluer la toxicité. Pour les NPs de CuO, la toxicité a été étudiée en conditions in vitro chez la lignée cellulaire Neuro-2A. Les NPs de CuO ont montré des effets cytotoxiques et génotoxiques sur ces cellules. La formation de micronoyaux était l'indicateur de toxicité le plus sensible, ce qui montre que la génotoxicité est un aspect important de la toxicité des NPs de CuO. Cette thèse permet de conclure que l'évaluation du risque toxicologique des NPs métalliques doit être réalisée en considération du changement de leurs propriétés physicochimiques selon le milieu utilisé et les modifications apportés aux NPs. La compréhension des liens entre les propriétés des NPs et leur toxicité peut permettre une utilisation plus sécuritaire des nanomatériaux dans les applications issues de la nanotechnologie. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : nanotoxicologie, génotoxicité, photosynthèse, fluorescence chlorophyllienne.

This thesis focuses on the design of a versatile, portable, and cost-effective fluorescence detection system for LOC devices. Components that are widely available are used, such as LEDs for excitation and a microcontroller for processing. In addition, a photoresistor is tested for the feasibility of being used as a fluorescence detector, instead of the more commonly used photomultiplier tubes. The device also focuses on upgradeability and versatility, meaning that most of the major components can be replaced as long as power requirements remain unaffected. This allows for future additions to the device once they are available, as well as giving the user the power to choose which add-ons are needed since not all users may have the same requirements. The performance of the device after testing with fluorescein dyes and stained yeast cells indicate that it is capable of executing simple tasks, such as determining the presence and concentration of an analyte if given a sufficient amount. It also provided similar readings to commercial fluorescence analysers, which proves its ability to function as a fluorescence detector device. The thesis also proposes a MEMS diffraction grating that can be used for wavelength tuning. By being able to selectively measure across a range of wavelengths, the capability of the device is increased. Examples include being able to detect multiple fluorescent emissions, which will complement the multicoloured excitation LED nicely. In addition, the device will not be limited to a predetermined set of filters. This effectively allows more fluorescent dyes to be used with the device since any wavelength in the visible range can be selectively filtered for. Simulations of the proposed diffraction grating were performed in ANSYS to confirm the validity of the calculated values. In addition, tests were performed on a slide fabricated with diffraction gratings using values as close to the calculated values as possible. All of the results indicate that there is great promise in the proposed diffraction grating design and that it should be further investigated.

Membrane filtration of protein solutions is influenced by a wide range of processing and physicochemical conditions. Monitoring and optimizing membrane filtration may have advantages for achieving, in a cost effective manner, improved bioproduct purification and membrane performance which is relevant to pharmaceutical and biochemical applications. The motivation of this work was to examine the feasibility of applying two-dimensional fluorescence spectroscopy in conjunction with chemometric techniques for monitoring and possibly optimizing the performance of membrane processes. Preliminary work focused on assessing the use of multivariate calibration tools in conjunction with the sensitivity of intrinsic protein fluorescence towards changes in environmental conditions was to predict protein concentration and aggregation behavior. A model protein, β-lactoglobulin (β-LG), was used as a first simple case scenario. Results showed very good agreement between the fluorescence based predictions and measurements obtained by HPLC and gravimetric analysis regardless of the conditions. PLS analysis of excitation-emission matrices revealed unique spectral fingerprints that are most likely associated with the heat-induced denaturation and aggregation. Standard Normal Variate, a signal preprocessing and filtering tool, was shown to have a significant effect on enhancing the predictive accuracy and robustness of the PLS model as it reduced the effect of instrumental noise. The methodology was then extended to a two-component protein system consisting of α- lactlalbumin (α-LA) and β-lactoglobulin (β-LG). The process of thermal induced aggregation of β-LG and α-LA protein in mixtures, which involves the disappearance of native-like proteins, was studied under various treatment conditions including different temperatures, pH, total initial protein concentration and proportions of α-LA and β-LG. A Partial Least Squares (PLS) regression algorithm was used to correlate the concentrations of α-LA and β-LG to the fluorescence spectra obtained for mixtures.The results illustrated that multivariate models could effectively deconvolute multiwavelength fluorescence spectra collected for the protein mixtures and thereby provide a fairly accurate quantification of respective native-like α-LA and β-LG despite the significant overlap between their emission profiles. It was also demonstrated that a PLS model could be used as a black-box prediction tool for estimating protein aggregation when combined with simple mass balances. Ultrafiltration experiments of the whey protein isolate solutions were carried out in dead-end filtration mode and fluorescence measurements of permeate and retentate solutions were acquired in synchronous scanning mode using a fiber optic probe. By implementing a dilution strategy for the retentate side, the fluorescence based PLS model encompassed a low protein concentration range where fluorescence was not expected to be significantly influenced by concentration-dependent interferences. It was also demonstrated that synchronous spectra can provide good predictions and consequently the use of the full spectrum may not be necessary for monitoring with corresponding savings in acquisition time. Membrane performance variables that are difficult to measure, such as individual protein transmission and membrane selectivity could be estimated directly from fluorescence-based predictions of protein concentrations in the retentate and permeate streams. Multiwavelength light scattering spectra, acquired using the fiber optic probe, were shown to be a useful indicator for protein self-association behavior, which is known to influence the membrane filtration. High fouling potential were observed for protein solutions that exhibited significant Rayleigh scattering. A predictive PLS model for estimating protein aggregation from Rayleigh scattering measurements was developed and it was tested by using molecular weight experimental values obtained from the literature. Although this comparison was only partial due to the limited amount of molecular weight data available, the findings verified the possibility of estimating the aggregate size from multiwavelength Rayleigh scattering spectra acquired using a conventional spectrofluorometer. Thus, the results implied that both intrinsic fluorescence and light scattering multiwavelength measurements could provide complementary information about the filtration process.

The Laurentian Great Lakes are the largest system of freshwater on earth containing 22% of the world’s supply. Although part of a single system, each lake shows substantial variation regarding physical, chemical and biological parameters. The main goals of this thesis were to characterize the nutrient status of natural phytoplankton communities while comparing several commonly used measurements of nutrient status and Chlorophyll a (Chl a) fluorescence measurements. The study sites include the western basin (WB), west-central basin (WCB), and central basin (CB) of Lake Erie, the Bay of Quinte in Lake Ontario, and Colpoys Bay in Lake Huron. Independent measures of nutrient status were assessed by measurements of nitrogen (N) debt, phosphorus (P) debt, particulate C:N:P ratios, and alkaline phosphatase activity (APA). Variable fluorescence of chlorophyll a was measured by pulse amplitude modulated (PAM) fluorometry and fast repetition rate (FRR) fluorometry in parallel with the independent measures. In 2005, the phytoplankton communities in Lake Erie were generally N deficient in May, P deficient in June, and neither N nor P deficient in September. The maximum dark adapted quantum yield (Fv/Fm) measured by PAM or FRRF was lower in May and June, and maximal in September, while the functional absorption cross section of photosystem II (σPSII) was maximal in May and June, and minimal in September. Relationships between the variable fluorescence indicators and independent measures of nutrient status showed strong associations with N or P deficient sites having low Fv/Fm and high σPSII. In 2006, the electron transport rate (ETR) and the initial slope (α) derived from the PAM fluorescence rapid light-response curves (RLC) were compared to independent measures and Fv/Fm measurements in Lake Erie. Relationships between ETR, α, independent measures of nutrient status, and Fv/Fm measurements revealed strong associations with nutrient status. Confirming previous reports, N deficiency was highest in the WB during isothermal conditions while P deficiency was highest in the CB during summer stratification. The fluorescence parameters generally decreased as the severity of N and P deficiency increased. N and P enrichment assays also revealed increased values of Fv/Fm, ETR, and α from N and P deficient samples over twenty-four hours. Additionally, spatial variability of P status was evaluated during summer stratification. Colpoys Bay, the most oligotrophic site, had the strongest P deficiency, and evidence for existence of P deficiency was weakest in the Bay of Quinte, the most eutrophic site. Nutrient enrichment assays revealed that all fluorescence parameters showed a positive response to P additions in oligotrophic sites, with no response in eutrophic sites. Community structure was also associated with nutrient status and Chl a fluorescence at all locations. In P deficient sites, nano-flagellates such as chrysophytes and cryptophytes were prevalent; cyanobacteria were dominant at sites that displayed N deficiency.

Le suivi des interactions entre protéines, localisées à la membrane plasmique ou à l'intérieur de cellules, a été réalisé au cours de cette thèse par imagerie de fluorescence et par l'analyse de processus dits de FRET (Forster Resonance Energy Transfer). Pour quantifier le FRET entre nos protéines d'intérêt, nous avons choisi le contraste de durée de vie de fluorescence car cette méthode est indépendante de la concentration et de l'intensité de fluorescence. Afin d'obtenir une résolution suffisante pour des problématiques neurobiologiques, un microscope TIRFLIM (Total Internal Reflection Fluorescence Lifetime Imaging Microscopy) avait préalablement été développé. Celui-ci nous permet de faire de l'imagerie en plein champ avec une résolution axiale sub-longueur d'onde. Ce dispositif a été calibré et optimisé au cours de cette thèse pour répondre au mieux à des problématiques biologiques. Différentes approches ont ainsi été testées dans le but de calibrer la profondeur de pénétration de l'onde évanescente. Des surfaces plasmoniques ont entre autres été utilisées pour augmenter la sélectivité axiale du montage. Notre microscope a été dédié à l'étude de l'effet du cholestérol sur l'interaction entre la protéine précurseur de l'amyloïde APP, protéine transmembranaire impliquée dans la maladie d'Alzheimer et une de ses enzymes de clivage BACE1. Nous avons ainsi effectué un suivi dynamique de l'effet du cholestérol sur l'interaction entre APP et BACE1 dans des cellules HEK-293 et dans des cultures primaires de neurones d'hippocampe d'embryons de rat, de la membrane plasmique à l'intérieur des cellules grâce à notre dispositif TIRFLIM. La mesure d'anisotropie de fluorescence résolue en temps a également été implémentée sur notre montage. Ces mesures résolues en temps et en polarisation ont permis de mesurer le temps de corrélation rotationnelle de fluorophores et de mettre en évidence de manière qualitative différents niveaux d'homodimérisation de protéines impliquées dans la maladie d'Alzheimer.

Variable fluorescence of chlorophyll a (Fv/Fm), measured by pulse amplitude modulated (PAM) fluorometers, is an attractive target for phytoplankton-related water quality management. Lowered Fv/Fm is believed to reflect the magnitude of nutrient sufficiency or deficiency in phytoplankton. This rapid and specific metric is relevant to Lake Erie, which often experiences problematic Cyanobacteria blooms. It is unknown whether PAMs reliably measure phytoplankton nutrient status or if different PAMs provide comparable results. Water samples collected from Lake Erie and two Lake Ontario sites in July and September 2011 were analysed using alkaline phosphatase assay (APA), P-debt, and N-debt to quantify phytoplankton nutrient status and with three different PAM models (PhytoPAM, WaterPAM and DivingPAM) to determine Fv/Fm. The Lake Ontario, Lake Erie East and Central Basin sites were all N- and P-deficient in July, but only the East and Central Basin and one Lake Ontario site were P-deficient in September. The West Basin sites were P-deficient in July and one West Basin site and a river site were N-deficient in September. Between-instrument Fv/Fm comparisons did not show the expected 1:1 relationship. Fv/Fm from the PhytoPAM and WaterPAM were well-correlated with each other but not with nutrient deficiency. DivingPAM Fv/Fm did not correlate with the other PAM models, but correlated with P-deficiency. Spectral PAM fluorometers (PhytoPAM) can potentially resolve Fv/Fm down to phytoplankton group by additionally measuring accessory pigment fluorescence. The nutrient-induced fluorescent transient (NIFT) is the observation that Fv/Fm drops immediately and recovers when the limiting nutrient is reintroduced to nutrient-starved phytoplankton. A controlled laboratory experiment was conducted on a 2x2 factorial mixture design of P-deficient and P-sufficient Asterionella formosa and Microcystis aeruginosa cultures. Patterns consistent with published reports of NIFT were observed for P-deficient M. aeruginosa in mixtures; the pattern for A. formosa was less clear. This thesis showed that Fv/Fm by itself was not a reliable metric of N or P deficiency and care must be taken when interpreting results obtained by different PAM fluorometers. NIFT analysis using spectral PAM fluorometers may be able to discriminate P-deficiency in M. aeruginosa, and possibly other Cyanobacteria, in mixed communities.

This thesis focuses on the design of a versatile, portable, and cost-effective fluorescence detection system for LOC devices. Components that are widely available are used, such as LEDs for excitation and a microcontroller for processing. In addition, a photoresistor is tested for the feasibility of being used as a fluorescence detector, instead of the more commonly used photomultiplier tubes. The device also focuses on upgradeability and versatility, meaning that most of the major components can be replaced as long as power requirements remain unaffected. This allows for future additions to the device once they are available, as well as giving the user the power to choose which add-ons are needed since not all users may have the same requirements. The performance of the device after testing with fluorescein dyes and stained yeast cells indicate that it is capable of executing simple tasks, such as determining the presence and concentration of an analyte if given a sufficient amount. It also provided similar readings to commercial fluorescence analysers, which proves its ability to function as a fluorescence detector device. The thesis also proposes a MEMS diffraction grating that can be used for wavelength tuning. By being able to selectively measure across a range of wavelengths, the capability of the device is increased. Examples include being able to detect multiple fluorescent emissions, which will complement the multicoloured excitation LED nicely. In addition, the device will not be limited to a predetermined set of filters. This effectively allows more fluorescent dyes to be used with the device since any wavelength in the visible range can be selectively filtered for. Simulations of the proposed diffraction grating were performed in ANSYS to confirm the validity of the calculated values. In addition, tests were performed on a slide fabricated with diffraction gratings using values as close to the calculated values as possible. All of the results indicate that there is great promise in the proposed diffraction grating design and that it should be further investigated.

Membrane filtration of protein solutions is influenced by a wide range of processing and physicochemical conditions. Monitoring and optimizing membrane filtration may have advantages for achieving, in a cost effective manner, improved bioproduct purification and membrane performance which is relevant to pharmaceutical and biochemical applications. The motivation of this work was to examine the feasibility of applying two-dimensional fluorescence spectroscopy in conjunction with chemometric techniques for monitoring and possibly optimizing the performance of membrane processes. Preliminary work focused on assessing the use of multivariate calibration tools in conjunction with the sensitivity of intrinsic protein fluorescence towards changes in environmental conditions was to predict protein concentration and aggregation behavior. A model protein, β-lactoglobulin (β-LG), was used as a first simple case scenario. Results showed very good agreement between the fluorescence based predictions and measurements obtained by HPLC and gravimetric analysis regardless of the conditions. PLS analysis of excitation-emission matrices revealed unique spectral fingerprints that are most likely associated with the heat-induced denaturation and aggregation. Standard Normal Variate, a signal preprocessing and filtering tool, was shown to have a significant effect on enhancing the predictive accuracy and robustness of the PLS model as it reduced the effect of instrumental noise. The methodology was then extended to a two-component protein system consisting of α- lactlalbumin (α-LA) and β-lactoglobulin (β-LG). The process of thermal induced aggregation of β-LG and α-LA protein in mixtures, which involves the disappearance of native-like proteins, was studied under various treatment conditions including different temperatures, pH, total initial protein concentration and proportions of α-LA and β-LG. A Partial Least Squares (PLS) regression algorithm was used to correlate the concentrations of α-LA and β-LG to the fluorescence spectra obtained for mixtures.The results illustrated that multivariate models could effectively deconvolute multiwavelength fluorescence spectra collected for the protein mixtures and thereby provide a fairly accurate quantification of respective native-like α-LA and β-LG despite the significant overlap between their emission profiles. It was also demonstrated that a PLS model could be used as a black-box prediction tool for estimating protein aggregation when combined with simple mass balances. Ultrafiltration experiments of the whey protein isolate solutions were carried out in dead-end filtration mode and fluorescence measurements of permeate and retentate solutions were acquired in synchronous scanning mode using a fiber optic probe. By implementing a dilution strategy for the retentate side, the fluorescence based PLS model encompassed a low protein concentration range where fluorescence was not expected to be significantly influenced by concentration-dependent interferences. It was also demonstrated that synchronous spectra can provide good predictions and consequently the use of the full spectrum may not be necessary for monitoring with corresponding savings in acquisition time. Membrane performance variables that are difficult to measure, such as individual protein transmission and membrane selectivity could be estimated directly from fluorescence-based predictions of protein concentrations in the retentate and permeate streams. Multiwavelength light scattering spectra, acquired using the fiber optic probe, were shown to be a useful indicator for protein self-association behavior, which is known to influence the membrane filtration. High fouling potential were observed for protein solutions that exhibited significant Rayleigh scattering. A predictive PLS model for estimating protein aggregation from Rayleigh scattering measurements was developed and it was tested by using molecular weight experimental values obtained from the literature. Although this comparison was only partial due to the limited amount of molecular weight data available, the findings verified the possibility of estimating the aggregate size from multiwavelength Rayleigh scattering spectra acquired using a conventional spectrofluorometer. Thus, the results implied that both intrinsic fluorescence and light scattering multiwavelength measurements could provide complementary information about the filtration process.