Dr Mounir Maafi

Job: Senior Lecturer

Faculty: Health and Life Sciences

School/department: Leicester School of Pharmacy

Address: De Montfort University, The Gateway, Leicester, LE1 9BH.

T: +44 (0)116 257 7704

E: mmaafi@dmu.ac.uk

W: www.dmu.ac.uk/hls

 

Personal profile

Mounir Maafi is a senior lecturer at the Leicester School of Pharmacy and he is an active researcher in drugs photostability and stabilisation. He holds an engineer degree from the National Institute of Industrial Chemistry (Algeria), a DEA in Spectrochemical Analysis of Organic and Biological Materials from Paris 6 - Paris 7 Universities, and a PhD in physical/analytical chemistry from Paris 7 University. Dr Maafi has held several Research Fellow/postdoctoral positions including at the Institute of Topology and System Dynamics (Paris, France), the Department of Analytical Chemistry (Badajoz, Spain), the Karolinska Institute at the Karolinska Hospital (Stockholm, Sweden), and at the University of Glamorgan (Cardiff, UK). He has also held university teaching positions as an Associate Professor at Marne La Vallée University, Paris 7 university and CPCM-Paris in France, and at University of Glamorgan at Cardiff. Dr Maafi is an editor for E-Journal of chemistry and a referee for several journals. He speaks five languages and hopes to learn a few more.

Research group affiliations

Chemistry for Health

Publications and outputs 

  • Φ-order spectrophotokinetic characterisation and quantification of trans-cis oxyresveratrol reactivity, photodegradation and actinometry.
    Φ-order spectrophotokinetic characterisation and quantification of trans-cis oxyresveratrol reactivity, photodegradation and actinometry. Maafi, Mounir; Alqarni, M. A new Φ-order kinetic method was proposed in this study for the investigation of trans-cis photoisomerization reaction of Oxyresveratol (ORVT) subjected to non-isosbestic irradiation. In ethanolic media, it has been proven that forward (Φ_(A→B)^(l_irr )) and reverse (Φ_(B→A)^(l_irr )) reaction quantum yields were dependent on the monochromatic irradation wavelength according to a sigmoid pattern over the spectral ranges of their electronic absorption (260-360 nm). An 11.4‐ and 6.6-fold increases were recorded for Φ_(B→A)^(_irr ) and Φ_(A→B)^(_irr ), respectively. The efficiencies of the former (Φ_(B→A)^(_irr ), ranging between 2.3 × 10-2 and 26.3 × 10-2) were 33 to 60 % smaller than those of the respective Φ_(A→B)^(l_irr ) measured at the irradiation wavelengths selected. Overall, between 57 and 97 % degradation of the initial trans-ORVT was observed under relatively weak light intensities, with the highest values recorded at the longest wavelengths. These findings strongly recommend protection from light in all situations of this biologically important phytomolecule that possesses therapeutic value of interest to pharmaceutical applications. The Φ-order kinetics also offered a simple way to develop a reliable actinometric method that proved ORVT to be an efficient actinometer for the dynamic range 295-360 nm. The usefulness of Φ‐order kinetics for the investigation and quantification of phytoproducts’ photodegradation was discussed. The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.
  • Modeling and Elucidation of the Kinetics of Multiple Consecutive Photoreactions AB4 (4Φ) With Φ-order Kinetics. Application to the Photodegradation of Riboflavin.
    Modeling and Elucidation of the Kinetics of Multiple Consecutive Photoreactions AB4 (4Φ) With Φ-order Kinetics. Application to the Photodegradation of Riboflavin. Maafi, W.; Maafi, Mounir New semi-empirical rate-law system of equations is proposed for the first time for consecutive photoreactions that involve up to 4 photoreaction steps, AB4(4Φ). The equation system was developed, tested, and validated against synthetic kinetic traces generated by fifth-order Runge-Kutta calculations. The model accurately fitted the kinetic traces of Riboflavin photodegradation in ethanol which decomposes via the AB2(2Φ) mechanism involving 2 consecutive photoreaction steps. A kinetic elucidation methodology useful for consecutive photoreactions was also proposed to determine all the kinetic parameters and reaction attributes defining AB2(2Φ) reactions. The quantum yields of photodegradation, determined for wavelengths in the visible region 400-480 nm, ranged from 0.005 to 0.00756 and 0.0012 to 8 10−5 for the first and second photoreaction steps, respectively. They were found to increase with wavelength in defined sigmoid functions. For this monochromatic irradiation range, riboflavin proved to be a useful actinometer. Finally, a photodegradation scale based on pseudo-rate-constant values was also proposed for drugs. This scale (including 4 groups) is thought to contribute to rationalizing photodegradation testing and might prove useful in categorizing drugs' photodegradation reactivity. The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.
  • Determination of Dacarbazine Φ‐Order Photokinetics, Quantum Yields, and Potential for Actinometry.
    Determination of Dacarbazine Φ‐Order Photokinetics, Quantum Yields, and Potential for Actinometry. Maafi, Mounir; Lee, Lok Yan The characterization of drugs’ Photodegradation kinetics is more accurately achieved by means of the recently developed –order kinetics than by the 0th–, 1st– and/or 2nd–order classical treatments. The photodegradation of anti–cancer Dacarbazine (DBZ) in ethanol has been investigated and found to obey –order kinetics when subjected to continuous and monochromatic irradiation of various wavelengths. Its photochemical efficiency was proven to be wavelength–dependent in the 220‐350 nm range, undergoing a 50–fold increase. Albeit this variation was well defined by a sigmoid pattern, the overall photoreactivity of DBZ was proven to depend also on the contributions of reactants’ and experimental attributes. The usefulness of DBZ to serve as a drug–actinometer has been investigated using the mathematical framework of –order kinetics. It has been shown that DBZ in ethanol can represent a good candidate for reliable actinometry in the range 270–350 nm. A detailed and easy–to–implement procedure has been proposed for DBZ–actinometry. This procedure could advantageously be implemented prior to the determination of the photodegradation quantum yields. This approach might be found useful for the development of many drug–actinometers as alternatives to quinine hydrochloride. The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.
  • Novel methods for the characterisation of nanosponges/drug complexes with fluorimetry. Detection and Quantification in human serum
    Novel methods for the characterisation of nanosponges/drug complexes with fluorimetry. Detection and Quantification in human serum Benson, G.; Maafi, Mounir; Grootveld, M. Cyclodextrins are oligosaccharides formed from a cyclic structure of 1,4-linked α-D-glucopyranose units, hydrophilic on the outside, and hydrophobic within they are able to form hydrogen bonds, van der Waals forces and hydrophobic interactions with non-polar guest molecules, including pharmaceuticals, altering their solubility and spectral properties, they are able to overcome biological barriers and be absorbed [1]. Cross-linking β-cyclodextrin with epichlorohydrin can create polymers, with modifiable properties, and greater solubility, which can form stronger inclusion complexes through both encapsulation, and adsorbing guest molecules to their exterior. Although this complexation has been investigated with some pharmaceuticals, enhancing their solubility [2], and yielding higher percentage recoveries than when monomeric β-cyclodextrin was used [3], it has also been found that an increase in the intensity of fluorimetric analytical signal also occurs as a result of this interaction, along with a shift in the maximum wavelength peak [4]. The inclusion complex doesn't appear to have been utilised for analytical chemistry purposes, therefore the drug-β-cyclodextrin polymer-complex was explored through fluorimetry, as it is anticipated that this will allow for lower pharmaceutical detection limits; this technique was then applied for the determination of drugs in human serum and canal water. This poster will illustrate how β-cyclodextrin polymer can be utilised to enhance the fluorimetric signal of drugs, and be applied for the detection of pharmaceuticals in human serum and canal water.
  • Usefulness of Φ-order kinetics for the investigation, characterisation and quantification of photodegradation processes
    Usefulness of Φ-order kinetics for the investigation, characterisation and quantification of photodegradation processes Maafi, Mounir; Alqarni, M. Φ-order kinetics has been shown to be the best tool to study photokinetics [1 – 6]. Various species have been studied using this approach including photochromes [1, 2] and drugs [3 – 6]. The unimolecular photodegradation processes of the form AB (1Φ) and photoreversible systems AB (2Φ), where A, the initial species phototransforms into a product B (A→B) which itself can return to A (A→B) via two distinct photoprocesses, each characterized each by an individual efficiency (Φ), have been mathematically described by integrated rate-law equations which express the so called 'Φ-order' kinetics [1 – 6]. The application of this novel approach was found to be useful to determine a number of photoreaction attributes. The reaction's photochemical quantum yield(s), the effects of initial species concentration, or the impact of competitive absorbers on the rate-constant of the photoactive species were all made readily accessible by simple methods. More importantly, the Φ-order kinetics has proven to facilitate the development of a wide range of actinometers from AB (1Φ) and AB (2Φ) systems [2 – 6]. This novel Φ-order kinetic method clearly has the potential for application in various fields including the photodegradation of natural products. The details of Φ-order elucidation kinetic methods will be discussed here and examples of application presented.
  • Quantitative assessment of photostability and photostabilisation of Fluvoxamine and its design for actinometry.
    Quantitative assessment of photostability and photostabilisation of Fluvoxamine and its design for actinometry. Maafi, Mounir; Maafi, Wassila Despite the numerous concerns that have been raised in relation to considering 0th, 1st and 2nd–order kinetic treatments for drugs’ photodegradation characterisation and assessments, yet they still are employed, as the only tool available for these types of studies. The recently developed –order kinetic models have opened new perspectives in the treatment of photoreaction kinetics that stands as the best known alternative to the classical approach. The –order kinetics have been applied here to Fluvoxamine (Fluvo) with the aim to set out a detailed and comprehensive procedure able to rationalise photodegradation/photostability of drugs and propose a platform for photosafety studies. Our results prove that drugs’ quantum yields (0.0016 <Φ􀮿􀯟􀯨􀯩􀯢 􀰒􀳔􀳝􀳝 < 0.43) should a priori be considered wavelength–dependent, their photostabilisation (up to 75% for Fluvo) by means of absorption competitors could explicitly be related to a decrease of the photokinetic factor, and photoreversible drugs can be developed into efficient actinometers (as Fluvoxamine in the 260–290 nm range). A pseudo– rate–constant factor was proposed as a descriptive parameter, circumventing the limitations of overall rateconstants and allowing comparison between drugs’ kinetic data obtained in different conditions. The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.
  • Actinometric and Φ-order photodegradation properties of anti-cancer Sunitinib.
    Actinometric and Φ-order photodegradation properties of anti-cancer Sunitinib. Maafi, Mounir; Lee, Lok Yan The photodegradation reaction of Sunitinib (SUT), occurring via Z–E photoisomerization, has been evaluated in this study using the recently developed –order kinetics. In ethanol, the forward (Z E) photoreaction of SUT was invariant with irradiation (its quantum yield, 0.019) in contrast to the E Z isomerisation whose undergoes a 30‐fold, sigmoid–shaped, increase with increasing irradiation wavelength. This situation limited usefully the extent of Z– SUT photodegradation at the photostationary state to a maximum of c.a. 30 % of the initial concentration. Nevertheless, these results support a strong recommendation for a complete protection of SUT from light at all stages. Furthermore, a SUT‐actinometer was developed and was proven to be useful for the 320–480 nm spectral range. The latter wavelength interval defined as well SUT photodegradation causative range. The formalism of –order kinetics, proves to be a useful investigative tool for drugs’ photodegradation studies. The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.
  • Quantification of unimolecular photoreaction kinetics: Determination of quantum yields and development of actinometers—The photodegradation case of cardiovascular drug Nisoldipine.
    Quantification of unimolecular photoreaction kinetics: Determination of quantum yields and development of actinometers—The photodegradation case of cardiovascular drug Nisoldipine. Maafi, Mounir; Maafi, Wassila The lack of integrated rate-laws for photoreactions has led to carry out the treatment of drugs photodegradation kinetic data using the classical zeroth-, first- and second-order kinetics that were originally developed for thermal reactions. The recent developments of –order kinetic models has opened new perspectives in the treatment of photoreaction kinetics of systems involving a photolabile molecule (A) transforming into a photochemically and thermally stable product (B), i.e. the AB(1) photoreaction systems. Within this framework, the kinetics of cardiovascular and photosensitive drug Nisoldipine (NIS) has been rationalised. Continuous and monochromatic irradiation of NIS in ethanol obeyed –order kinetics with a sigmoid–shaped quantum yield variation with irradiation wavelength (0.0041–0.35 within 235–390 nm spectral region). Both NIS initial concentration-induced self photostabilisation effect and the photostabilisation by absorption competitors were quantified (up 70 %) and related to a reduction of the photokinetic factor. Finally, the –order kinetics also served to demonstrate the actinometric potential of NIS for the 320–400 nm dynamic range. Open Access article
  • Φ-order kinetics of photoreversible-drug reactions
    Φ-order kinetics of photoreversible-drug reactions Maafi, Mounir; Maafi, W.
  • Ф-order kinetics of photoreversible-drug reactions.
    Ф-order kinetics of photoreversible-drug reactions. Maafi, Mounir; Maafi, Wassila Background: Drug 13 photodegradation data are usually treated by zero–, first– or second– order kinetic equations. Such treatments would lack reliability since the aforementioned equations have been originally developed for pure thermal reactions. In this respect, it has recently been shown that unimolecular photodegradations obey –order kinetics (Maafi and Maafi, 2013). However, no similar information is, thus far, available for other reactions including photoreversible AB(2) systems. This paper aims at filling this gap for AB(2) kinetics. Methods: Runge–Kutta numerical integration data for photoreversible reactions traces were combined with a template equation in order to derive an optimized (semi–empirical) integrated rate–law equation for AB(2) reactions. The proposed model equation was test by examining its ability to fit synthetic Runge–Kutta data that have not been used for the optimization. The obtained fitting parameters are then compared to their theoretical counterparts. Results: Both an integrated rate–law and an analytical equation for the overall reaction rate–constant were set for photoreversible drug reactions. The values of overall reaction rate–constant and initial velocity obtained theoretically correlated well with those obtained by fitting the kinetic traces of reactions with the derived integrated rate–law. AB(2) photodegradation reactions have been proven to obey –order kinetics. The equation proposed describes faithfully their kinetic behaviour in solution. The formula of the overall rate–constant involves both reagents characteristics and experimental parameters. These equations facilitated the rationalisation and prediction of the individual effects of each reaction parameter. Specially, our results proved a self–photostabilisation with increasing initial drug–concentration and demonstrated the potential for actinometry of drugs obeying AB(2) mechanism. The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.

Click here for a full listing of Mounir Maafi's publications and outputs.

Key research outputs

The potential of AB(1) systems for direct actinometry. Diarylethenes as successful actimometers for the visible range. M Maafi, Phys Chem Chem Phys, 2010 12 (40), pp 13248-13254.

A mathematical analysis and elucidation of AB(2k,1φ) thermophotochromic kinetics. An analytical solution using pure kinetic data and considering as unknown The rate constants, quantum yield and both species’ spectra. M Maafi, R G Brown, Int J Chem Kinet, 41(4), pp 255 – 264 2009.

Kinetic analysis and kinetic elucidation options for AB(1k,2) systems. New Spectrokinetic methods for photochromes. M Maafi, R G Brown. Photochem Photobiol Sci, 7, pp 1360 – 1372 2008.

Spectrokinetic Methods for the Investigation of Photochromic and Thermo-Photochromic Spiropyrans. M Maafi, Molecules 13(9), pp 2260-2302 2008.

Comment on “Photokinetic methods: A mathematical analysis of the rate equations in photochromic systems; by G Ottavi, F Ortica, G Favaro, Int J Chem Kinet, 1999 31, 303-313.” M Maafi, Int J Chem Kinet, 40, pp 524-525 2008.

A Fundamental system of equation to describe ABC(3k,6 dynamics. Contribution to the elucdation of [2H]-naphthopyran kinetics. M Maafi, R G Brown, Int J Chem Kinet, 40, pp 268-281 2008.

The kinetic model for AB(1) systems. A Closed-form integration of the differential equation with a variable photokinetic factor. M Maafi, R G Brown, J Photochem Photobiol A:Chem, 187, pp.319-324 2007.

Research interests/expertise

  • Modelling photoreactions and spectrokinetics
  • Thermochromes and photochromic materials
  • Drug phodegradation and stabilisation
  • Drug specials
  • Anticancer, synthetic hormone and cardiovascular drugs
  • Cyclodextrin superamolecular systems
  • Drug delivery systems
  • Development of analytical methods for soil analysis.

Areas of teaching

  • Spectroscopy/spectrochmistry
  • Analytical chemistry
  • Physical chemistry and thermodynamics
  • Drug formulation and stability
  • Project supervision at undergraduate and postgraduate levels MPhil and PhD.

Qualifications

Engineer, DEA, PhD

Honours and awards

  • The Marquise index Who’s Who in the World, Editions 2008
  • The Dictionary of International Biography, 34th edition, Cambridge 2008
  • Nominated for a DMU Vice Chancellors Distinguished Teaching Award.

Conference attendance

Kinetic tools for the investigation of unimolecular and bimolecular photoreactions of drugs. Potential for actinometry. 7th International Meeting on the Photostability of Drugs and Drug Products (1–3 October 2008). M Maafi, London.

A semi empirical kinetic law for AB(2φ) systems. usefulness for direct actinometry. XXII IUPAC Symposium on photochemistry (28 July–1 August 2008), M Maafi, Gothenburg, Sweden.

A complete elucidation of AB(2k,1φ) ThermoPhoto-Chromic Kinetics. A Mathematically Analytical method based on Pure Kinetic Data. XXII IUPAC Symposium on photochemistry (28 July–1 August 2008), M Maafi, R G Brown, Gothenburg, Sweden.

Current research students

First supervisor for the following PhD students: Damerdji Wassila, Lok Yan Lee, Leonie Hough.

Externally funded research grants information

In preparation: a research project on drugs stability.

Professional esteem indicators

E-Journal of chemistry and a referee for several journals.

Case studies

Citation in international journals in the year 2011.

Angewandte Chemie - International Edition : Imprinting chemical and responsive micropatterns into metal-organic frameworks, Han S, Wei Y, Valente C, Forgan R S, Gassensmith J J, Smaldone R A, Nakanishi H, (...), Grzybowski B A, 50 (1), pp 276-279 2011.

Journal of Photochemistry and Photobiology C: Photochemistry Reviews : Quantitative analysis of the dynamic behaviour of photochromic systems. Delbaere, S, Vermeersch,G, Micheau,J-C, 12(2), pp 74–105 2011.

Phys Chem Chem Phys: Tuning of switching properties and excited-state dynamics of fulgides by structural modifications, Ron Siewertsen, Frank Strübe, Jochen Mattay, Falk Renth and Friedrich Temps, 13, pp 3800-3808 2011.

European Journal of Organic Chemistry : Photochromism of Rotation-Hindered Furylfulgides Influenced by Steric Modifications, Frank Strübe, Ron Siewertsen, Frank D. Sönnichsen, Falk Renth, Friedrich Temps, Jochen Mattay, pp 1947–1955 2011.

Chemical Physics Letters : Deciphering the host–guest chemistry of Acridine Yellow and Cucurbit[7]uril: An integrated spectroscopic and calorimetric study, Brotati Chakraborty, Samita Basu, 507(1-3), pp 74-79 2011.

Photochemistry : Photochemistry of aromatic compounds. Mizuno,K, 38, pp 168-209 2011.

Journal of Molecular Liquids: Solvent effect on the spectroscopic properties of 6MAMC and 7MAMC, Melavanki,R M, Patil,N R, Kapatkar,S B, Ayachit,N H, Umapathy,S, Thipperudrappa,J, Nataraju,A R, 158 (2), pp 105-110 2011.

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy : Comments on the determination of excited state dipole moment of molecules using the method of solvatochromism A Kawski, P Bojarski, 82 (1), pp 527-528 2011.

Photochemistry: Photochemistry of aromatic compounds. Mizuno,K, 38, pp 168-209 2011.

Photochemistry: Alkenes, alkynes, dienes, polyenes. Tsuno,T, 38, pp 110-142, 2011.

Book: Dey,D, Kumar Sarangi,M and Basu,S (2011) Chapter 9 : Hydrogen Bonding on Photoexcitation, in Hydrogen Bonding and Transfer in the Excited State, Volume I & II (eds K.-L. Han and G.-J. Zhao), John Wiley & Sons Ltd, Chichester, UK.

Book : Timcheva,I and Nikolov,P (2011) Chapter 12 : Intermolecular Hydrogen Bonding in the Fluorescence Excited State of Organic Luminophores Containing Both Carbonyl and Amino Groups, in Hydrogen Bonding and Transfer in the Excited State, Volume I & II (eds K.-L. Han and G.-J. Zhao), John Wiley & Sons Ltd, Chichester, UK.

Journal of Advanced Research in Physics: Solvent effects on the electronic absorption and fluorescence spectra, Mihaela Homocianu1, Anton Airinei and Dana Ortansa Dorohoi, 2(1), 011105, 2011.

Journal of Photochemistry and Photobiology A: Chemistry: Chemical reactions of benzophenone photoirradiated in 1,2-polybutadiene. Barboiu,V, Avadanei,M I, 222(1), pp 170-179 2011.

Journal of Molecular Liquids: On the ground and excited state dipole moments of dansylamide from solvatochromic shifts of absorption and fluorescence spectra. Tewari,N, Joshi,N K, Rautela,R, Gahlaut,R, Joshi,H C, Pant,S, 160(3), pp 150-153 2011.

Research Advance in the Effects of β-Cyclodextrin and Its Derivatives on Fluorescence Enhancement, Zhang Min, Zhang Yu-hao, Ma Liang , Vol 32, No 01 297 2011.

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