MOMO - multi-objective metabolic mixed integer optimization: application to yeast strain engineering.

Background: In this paper, we explore the concept of multi-objective optimization in the field of metabolic engineering when both continuous and integer decision variables are involved in the model. In particular, we propose a multi-objective model that may be used to suggest reaction deletions that maximize and/or minimize several functions simultaneously. The applications may include, among others, the concurrent maximization of a bioproduct and of biomass, or maximization of a bioproduct while minimizing the formation of a given by-product, two common requirements in microbial metabolic engineering.

Physical and chemical immobilization of choline oxidase onto different porous solid supports: Adsorption studies.

This work carries out for the first time the comparison between the physical and chemical immobilization of choline oxidase onto aminated silica-based porous supports. The influence on the immobilization efficiency of concentration, pH, temperature and contact time between the support and choline oxidase, was evaluated. The immobilization efficiency was estimated taking into consideration the choline oxidase activity, which was assessed by using cadmium telluride (CdTe) quantum dots (QDs), obtained by hydrothermal synthesis, as photoluminescent probes.

Nanoparticle-based assays in automated flow systems: A review.

Nanoparticles (NPs) exhibit a number of distinctive and entrancing properties that explain their ever increasing application in analytical chemistry, mainly as chemosensors, signaling tags, catalysts, analytical signal enhancers, reactive species generators, analyte recognition and scavenging/separation entities. The prospect of associating NPs with automated flow-based analytical is undoubtedly a challenging perspective as it would permit confined, cost-effective and reliable analysis, within a shorter timeframe, while exploiting the features of NPs. This article aims at examining state-of-the-art on continuous flow analysis and microfluidic approaches involving NPs such as noble metals (gold and silver), magnetic materials, carbon, silica or quantum dots.

[The National Comprehensive Health Policy for the Black Population: implementation, awareness and socioeconomic aspects from the perspective of this ethnic group].

The scope of the National Comprehensive Health Policy for the Black Population is to ensure equitable health care to this population. This policy is to compensate for the discrimination suffered by this ethnic group throughout the history of Brazil. The black population presents higher social and economic vulnerability, leading to shorter life expectancy and an increased susceptibility to diseases.

Antioxidant capacity automatic assay based on inline photogenerated radical species from L-glutathione-capped CdTe quantum dots.

This work aimed at the development of a methodology implemented in an automatic flow system for determination of the antioxidant capacity in food samples, based on the luminol oxidation by inline photogenerated radical species from cadmium telluride nanoparticles capped with L-glutathione. Radical species were generated inline by a high-power visible light obtained by Light Emitting Diodes (LEDs) assembled in a multipumping flow system (MPFS). The use of visible light instead of UV radiation allowed the development of a new methodology for antioxidant capacity determination, more environment friendly and to circumvent the risk for UV photo-induced degradation of sample antioxidant compounds.

Immobilization of Distinctly Capped CdTe Quantum Dots onto Porous Aminated Solid Supports.

Immobilization of quantum dots (QDs) onto solid supports could improve their applicability in the development of sensing platforms and solid-phase reactors by allowing the implementation of reusable surfaces and the execution of repetitive procedures. As the reactivity of QDs relies mostly on their surface chemistry, immobilization could also limit the disruption of solution stability that could prevent stable measurements. Herein, distinct strategies to immobilize QDs onto porous aminated supports, such as physical adsorption and the establishment of chemical linking, were evaluated.

Enhancing reactive species generation upon photo-activation of CdTe quantum dots for the chemiluminometric determination of unreacted reagent in UV/S2O8(2-) drug degradation process.

A new chemiluminescence (CL) flow method for persulfate determination was developed based on luminol oxidation by in-line generated radicals. Reactive oxygen species (ROS) generated by CdTe quantum dots (QDs) under a low energetic radiation (visible light emitted by LEDs) promoted the decomposition of persulfate ion (S2O8(2-)) into sulfate radical (SO4(∙-)), leading to subsequent radical chain reactions that yield the emission of light. Due to the inherent radical short lifetimes and the transient behavior of CL phenomena an automated multi-pumping flow system (MPFS) was proposed to improve sample manipulation and reaction zone implementation ensuring reproducible analysis time and high sampling rate.

Fluorescence enhancement of CdTe MPA-capped quantum dots by glutathione for hydrogen peroxide determination.

The manipulation of the surface chemistry of semiconductor nanocrystals has been exploited to implement distinct sensing strategies in many analytical applications. In this work, reduced glutathione (GSH) was added at reaction time, as an electron-donor ligand, to markedly increase the quantum yield and the emission efficiency of MPA-capped CdTe quantum dots. The developed approach was employed in the implementation of an automated flow methodology for hydrogen peroxide determination, as this can oxidize GSH preventing its surface passivating effect and producing a manifest fluorescence quenching.

Evaluation of chemical constituents and antioxidant activity of coconut water (Cocus nucifera L.) and caffeic acid in cell culture.

Coconut water contains several uncharacterized substances and is widely used in the human consumption. In this paper we detected and quantified ascorbic acid and caffeic acid and total phenolics in several varieties of coconut using HPLS/MS/MS (25.8 ± 0.

A soft strategy for covalent immobilization of glutathione and cysteine capped quantum dots onto amino functionalized surfaces.

A novel strategy for immobilization of CdTe quantum dots (QDs) onto amino functionalized solid supports was developed. QDs capped with compounds holding an amino group were covalently bonded to the substrate under mild reaction conditions, exhibiting great stability and strong luminescence.

Chemiluminometric determination of captopril in a multi-pumping flow system.

In this work, a simple, versatile and fully automated analytical methodology for the chemiluminometric determination of captopril - an angiotensin II-converting-enzyme (ACE) inhibitor - in pharmaceutical formulations, is proposed. The developed methodology was based on the enhancement by captopril of the chemiluminescence emission of tris(2,2'-bipyridyl)ruthenium(II). In sulphuric acid medium tris(2,2'-bipyridyl)ruthenium(II) was oxidized by cerium(IV) and converted into a reactive oxidant specie [Ru(bpy)(3)](3+), which was subsequently reduced with captopril in order to yield a significant enhancement of the original chemiluminescence emission that was directly related to captopril concentration.

Evaluation of acetylcysteine promoting effect on CdTe nanocrystals photoluminescence by using a multipumping flow system.

A simple and straightforward quantification method integrated in a fully automated multi-pumping flow system (MPFS) using water-soluble mercaptopropionic acid (MPA)-capped CdTe quantum dots (QDs) was implemented for the fluorescence quantification of N-acetyl-L-cysteine (NAC) in pharmaceutical formulations. The developed approach was based on NAC ability to establish surface interactions that result in enhanced nanocrystals fluorescence intensity, proportional to analyte concentration. Size and concentration of QDs, ageing, composition, concentration and pH of the buffer solution revealed to have a noticeable effect on the enhancing efficiency affecting sensitivity and linear working range of the methodology.

Photoactivation by visible light of CdTe quantum dots for inline generation of reactive oxygen species in an automated multipumping flow system.

Quantum dots (QD) are semiconductor nanocrystals able to generate free radical species upon exposure to an electromagnetic radiation, usually in the ultraviolet wavelength range. In this work, CdTe QD were used as highly reactive oxygen species (ROS) generators for the control of pharmaceutical formulations containing epinephrine. The developed approach was based on the chemiluminometric monitoring of the quenching effect of epinephrine on the oxidation of luminol by the produced ROS.

Application of quantum dots as analytical tools in automated chemical analysis: a review.

Colloidal semiconductor nanocrystals or quantum dots (QDs) are one of the most relevant developments in the fast-growing world of nanotechnology. Initially proposed as luminescent biological labels, they are finding new important fields of application in analytical chemistry, where their photoluminescent properties have been exploited in environmental monitoring, pharmaceutical and clinical analysis and food quality control. Despite the enormous variety of applications that have been developed, the automation of QDs-based analytical methodologies by resorting to automation tools such as continuous flow analysis and related techniques, which would allow to take advantage of particular features of the nanocrystals such as the versatile surface chemistry and ligand binding ability, the aptitude to generate reactive species, the possibility of encapsulation in different materials while retaining native luminescence providing the means for the implementation of renewable chemosensors or even the utilisation of more drastic and even stability impairing reaction conditions, is hitherto very limited.

Exploiting adsorption and desorption at solid-liquid interface for the fluorometric monitoring of glibenclamide in adulterated drinks.

Nowadays, the use of a drug to modify a person's behavior with criminal intentions has become a growing public concern. In fact, stealthy drink spiking with certain drugs can cause the incapacitation of a potential victim of assault and in extreme cases can even lead to death. Belonging to the group of drugs used to commit drug-facilitated crimes is glibenclamide, which not only exhibits high sedation secondary effects but when subject to an overdose intake can lead to intense hypoglycemic episodes that could end with death.

Chemiluminometric evaluation of melatonin and selected melatonin precursors' interaction with reactive oxygen and nitrogen species.

Melatonin is a hormone, a derivative of tryptophan, that possesses a potent scavenging capacity for the most reactive and dangerous free radicals, being an important protection against oxidative stress. In this work, an automated flow-based procedure for assessment of melatonin, tryptophan, and 5-hydroxytryptophan scavenging capacity was developed. The presented methodology involved a multi-pumping flow system and exploited the ability of selected compounds to inhibit the chemiluminescence reaction of luminol with hydrogen peroxide, hydroxyl radical, and peroxynitrite anion.

Automatic multi-pumping flow system for the chemiluminometric screening of scavenging capacity against singlet oxygen.

An automated multi-pumping flow system was developed for the in-line generation of singlet oxygen ((1)O(2)) and subsequent assessment of the scavenging capacity against this reactive species. (1)O(2) was generated by dismutation of hydrogen peroxide catalyzed by molybdate ions. The evaluation of the scavenging capacity was based on the inhibition of the chemiluminescence reaction of luminol with (1)O(2).

Quantum dots assisted photocatalysis for the chemiluminometric determination of chemical oxygen demand using a single interface flow system.

A novel flow method for the determination of chemical oxygen demand (COD) is proposed in this work. It relies on the combination of a fully automated single interface flow system, an on-line UV photocatalytic unit and quantum dot (QD) nanotechnology. The developed approach takes advantage of CdTe nanocrystals capacity to generate strong oxidizing species upon irradiation with UV light, which fostered a fast catalytic degradation of the organic compounds.

Automatic miniaturized fluorometric flow system for chemical and toxicological control of glibenclamide.

In this work, and for the first time, it was developed an automatic and fast screening miniaturized flow system for the toxicological control of glibenclamide in beverages, with application in forensic laboratory investigations, and also, for the chemical control of commercially available pharmaceutical formulations. The automatic system exploited the multipumping flow (MPFS) concept and allowed the implementation of a new glibenclamide determination method based on the fluorometric monitoring of the drug in acidic medium (λ(ex)=301 nm; λ(em)=404 nm), in the presence of an anionic surfactant (SDS), promoting an organized micellar medium to enhance the fluorometric measurements. The developed approach assured good recoveries in the analysis of five spiked alcoholic beverages.

Cadmium telluride nanocrystals as luminescent sensitizers in flow analysis.

A fully automated multipumping flow system (MPFS) using water-soluble CdTe quantum dots (QD) as sensitizers is proposed for the chemiluminometric determination of the anti-diabetic drugs gliclazide and glipizide in pharmaceutical formulations. The nanocrystals acted as enhancers of the weak CL emission produced upon oxidation of sulphite by Ce(IV) in acidic medium, thus improving sensitivity and expanding the dynamical analytical concentration range. By interacting with the QD, the two analytes prevented their sensitizing effect yielding a chemiluminescence quenching of the Ce(IV)-SO(3)(2-)CdTe QD system.

A reagent-free method based on a photo-induced fluorimetry in a sequential injection system.

According to the current demands of environmentally friendly analytical chemistry and with a view to achieving lower reagent consumption with improved analytical performance, an automatic methodology composed of a photoreactor and fluorimetric detection (λ(exc)=287 nm, λ(em)=378 nm) was developed. To this end, a sequential injection analysis (SIA) system was developed for indomethacin determination using ultra-violet (UV) light which promotes an increase in the fluorescence of indomethacin. This increase in sensitivity makes it possible to apply this methodology to a dissolution test and to determine indomethacin in pharmaceutical formulations.

Automated determination of diazepam in spiked alcoholic beverages associated with drug-facilitated crimes.

In this work, a multipumping flow system (MPFS) coupled to a photodegradation unit was developed, for the first time, for the determination of diazepam (a benzodiazepine) in spiked alcoholic beverages by fluorimetry. The main features of MPFS such as, high portability, versatility and straightforward automation and control combined with the efficiency and simplicity of photodegradation and the selectivity and sensitivity of fluorimetric detection makes the developed analytical methodology an attractive tool and a valuable contribution for the prevention of drug-facilitated crimes (DFC). Drug-facilitated crimes involve the unauthorized administration of strong central nervous system depressant drugs, which have the capability of preventing victims from resist to the action of the perpetrator or fighting off.

Exploitation of a single interface flow system for on-line aqueous biphasic extraction.

The exploitation of aqueous biphasic extraction is proposed for the first time in flow analysis. This extraction strategy stands out for being environmentally attractive since it is based in the utilization of two immiscible phases that are intrinsically aqueous. The organic solvents of the traditional liquid-liquid extractions are no longer used, being replaced by non-toxic, non-flammable and non-volatile ones.

Diazepam fluorimetric monitoring upon photo-degradation in an automatic miniaturized flow system.

The present work describes the fully integration in line of a photo-degradation unit, comprising a low pressure UV lamp, in a Multipumping Flow System (MPFS), for the fluorimetric chemical control of commercially available pharmaceutical formulations containing diazepam. The utilization of an organized micellar medium provided enhanced fluorescence emission. The results allowed to obtain a linear working range for diazepam concentrations of up to 40 mg L(-1) (r = 0.

Oscillating chemiluminescence systems: state of the art.

Oscillating chemiluminescence (CL) was reported for the first time about 30 years ago. Since then several systems based on addition of a chemiluminescent reagent to a known oscillator system or based on the light emitting features of one component of the oscillating system, have been described. This information, scattered in the scientific literature, is compiled in the present paper.