Molecularly Imprinted Polymers for Pharmaceutical Compounds: Synthetic Procedures and Analytical Applications

In this chapter, the synthetic procedures for molecularly imprinted polymers (MIPs) for pharmaceutical compounds are discussed. Regardless of its limitations, such as production of irregular particles and loss of sample during processing (crushing and sieving), bulk polymerization has been widely used compared to say precipitation and suspension polymerization partly due to its simplicity in synthesis and robustness. A comparison of indomethacin removal from aqueous solution by MIP particles prepared using bulk polymerization to those obtained from suspension polymerization showed that the particles from the former exhibited higher adsorption capacity. Furthermore, the chapter explores the strengths and limitations relating the use of pharmaceutical compounds as uni-templates, multi-templates and dummy templates. Also, the analytical applications of MIPs are discussed in more details with particular focus on molecularly imprinted solid-phase extraction (MISPE) of pharmaceuticals from environmental samples. This application (MISPE) is currently the most exploited in literature as more pharmaceutical drugs find their way into environmental water bodies

Metal Adsorption by Coal Fly Ash: The Role of Nano-sized Materials

Nano-sized particles (1–100 nm) comprise a considerable fraction of coal fly ash (CFA). They are unique due to their large surface area and higher reactivity compared to larger CFA particles. As they are formed by nucleation of volatilised elements or through chemical reactions, nano-scale CFA particles have been shown to take up greater quantities of elemental ions and bind them more strongly than larger particles, diminishing the fraction of desorbed ions. Despite this and the large volume of literature on acid mine drainage (AMD) treatment using CFA, little is described about the specific role of nanoparticles in this process. This chapter therefore sets out to highlight this, beginning by delineating nanoparticle characteristics that make them good adsorbents followed by details of their formation and action in metal adsorption

The integration of previously hospital based Antiretroviral sites into Primary Health Care clinics in Lukhanji sub district of Chris Hani District Municipality

The first country to take note of HIV/AIDS was United States of America in the report published by Atlanta based Centers for Disease Control (CDC) and Prevention (Barnett and Whiteside, 2006). In the past years ARV program was largely hospital-based where clients were assessed by doctors, discussed with multidisciplinary team which involved social workers, dieticians and pharmacists before initiated on treatment. The integration of ARV services into PHC was one of the strategies proposed to increase access to treatment for people living with HIV/AIDS (WHO, 2010). The study sought to describe the integration of previously hospital based ARV sites into PHC clinics in Lukhanji sub-district of Chris Hani Health District in Eastern Cape. A qualitative research design was followed and a phenomenological approach was used to examine the experiences of clients who previously took ARV treatment at Frontier hospital and were transferred to take treatment at Ezibeleni, Ilinge, Philani and Sada clinics. An interview guide was used for data collection. Participants were sampled through purposive sampling. The study was composed of four focus groups for clients with a total of forty (18 males and 22 females) and 10 professional nurses for semi structured individual interviews. In the analysis of data, the collected data from voice recordings were transcribed verbatim and translated from isiXhosa to English. The researcher immersed herself into the data, re read, and themes and sub-themes emerged. Related topics to each other were grouped together in order to reduce the number of categories and to create themes. The similar categories were grouped and analyzed. Findings indicated that integration of ART sites into PHC clinics was a strategy put in place to increase accessibility and availability of ARV treatment to all communities. Both participants stated that integration brought services nearer to people and caused much relief from spending more money for travelling long distances. Ambulance delays were reported by both participants as the major challenge in the referral system between clinics and the hospital. Other challenges facing integration of ART services into PHC clinics included long waiting times caused by shortage of staff in the clinics, lack of consulting rooms for nurses and waiting areas for clients. Also lack of other health care professionals including social workers, dieticians, and psychologists was mentioned. The recommendations made by the researcher on the conclusion of this study addressed all the challenges mentioned by participants. The aim was to increase accessibility and availability of ART services to all the communities

Genotoxicity and tumor inducing potential of roadside soil samples exposed to heavy traffic emissions at Amritsar (Punjab), India

Noxious gases released from vehicles adversely affect the microbial population of the roadside soil as well as exerts influence on plant growth and development. Considering the increasing vehicular pollution in Amritsar, a holy city of Punjab (India) and their serious consequences in terms of health problems, the present study was planned to estimate genotoxic and tumor inducing potentials of soil samples from Golden temple (GT) and Putlighar Chowk (PG) by employing Allium cepa root chromosomal aberration assay (AlRCAA) and Potato disc tumor assay (PDTA), respectively. The genotoxic potential in terms of percent aberrant cells in A. cepa was found to be 29.24 % (GT) and 29.24 % (PG) during in situ treatment and 39.00 % (GT) and 39.48 % (PG) during root dip treatment. The average number of tumors was found to be 14.4 in PG sample, followed by 13.0 in GT sample. Both samples have shown high content of lead viz., 39.81 (GT) and 56.48 (PG) during physicochemical analysis of the samples

Development and application of imprinted polymers for selective adsorption of metal Ions and flavonols in complex Samples

Presence of heavy metals in the environment is a worldwide known contamination problem. Depending on their chemistries and level of contamination, these heavy metals can have severe effects on the ecosystem, aquatic life and eventually humans. Researchers have been particularly interested in finding methods for the removal of these pollutants from the environment. Several methods have been proposed and some have been used with some degree of success. Methods used for trace metal removal include, chemical precipitation, chemical reduction, solvent extraction, micellar ultrafiltration, organic and inorganic ion exchange, adsorption processes, etc. However, the matrix in which these heavy metals are present in is sometimes very complex and some of these heavy metals are present in the environment at very low concentrations, say ppb levels. However, they can have adverse effects even at such low-level concentrations. The above-mentioned methods usually suffer from the effects of the matrix and by-products produced after treatment such as sludge in the case of precipitation. Hence, in this study molecularly imprinted polymers (MIPs) were used. MIPs are highly cross-linked polymers prepared with the presence of template molecule. Once the template has been removed it leaves behind a cavity that can only fit the template, hence MIPs are very selective for the template molecule. Metals of interest in this study were uranium (VI) and chromium (VI). Therefore, two separate imprinted polymers were prepared using chromium and uranium as template molecules for selective extraction of these oxy-ions from aqueous samples. Beside removal of heavy metals, the study also focussed on developing MIPs for selective recovery of high value compounds from plant materials (onion and Moringa oleifera). Three separate imprinted polymers using chromium, uranium or quercetin templates were prepared by bulk polymerization method. Functional monomers used were 4-vinylpyridine; 1-(prop-2-en-1-yl)-4-(pyridin-2-ylmethyl)piperazine (PPMP) and methacrylic acid; and 4-vinylpyridine for chromium, uranium and quercetin imprinted polymers, respectively. For all imprinted polymers, ethylene glycol dimethacrylate (EDMA) and 1,1‘-azobis(cyclohexanecarbonitrile) (ACCN) were used as the cross-linking monomer and initiator, respectively. Control polymers (CP) or non-imprinted polymers (NIP) for each imprinted polymer were prepared and treated exactly the same as imprinted polymers but with omission of respective templates. Following removal of respective templates with appropriate solutions, various parameters that affect selective adsorption such as solution pH, initial concentration, aqueous phase volume, sorbent dosage, contact time, breakthrough volumes etc., were optimized to get optimal adsorption of the imprinted polymers. Optimal parameters for Cr (VI) adsorption were as follows: solution pH, 3; contact time, 120 min; eluent, 20 mL of 0.1 M NaOH; and sorbent amount, 125 mg. Maximum retention capacity of IIP and CP was 37.58 and 25.44 mg g-1, respectively. The observed selectivity order was as follows, Cr (VI) > SO4 2- > F- > PO4 3- > NO2 - > NO3 - > Cl-. However, in the presence of high concentrations of sulphate ions, the selectivity on the CP completely collapsed. For uranium VI removal, the optimal pH was 4.0-8.0, sorbent amount was 20 mg, contact time was 20 min and the retention capacity was 120 mg of uranyl ion per g of IIP. The selectivity order observed was as follows, UO2 2+ > Fe3+ >> Cu2+ > Co2+ > Mn2+ > Zn2+ ~ Ni2+. The binding capacity of quercetin MIPs was investigated at 25 and 84°C, respectively, in batch mode. The slopes for the effect of extraction time revealed that the mass transfer of the analytes was higher at 84°C than at 25°C. Also, the binding capacity for the most promising MIP and its corresponding NIP increased at 84°C but the MIP had higher binding capacity. The increase in binding capacity for the MIP was from ~30 μmol g-1 at 25°C to ~120 μmol g-1 at 84°C. For the corresponding NIP, the binding capacity values were ~15 and ~90 μmol g-1, at 25 and 84°C, respectively. A demonstration of MIP selectivity at higher temperature using standard solutions of selected flavonols showed that the MIP still retained its selectivity for quercetin. Similar selectivity was observed when preliminary application studies on aqueous yellow onion extracts were investigated. The study clearly demonstrated the suitability of the developed imprinted polymers (for chromium, uranium and quercetin) for selective adsorption of Cr (VI), UO2 2+ and quercetin from their respective complex matrices. Breakthrough volume of molecular imprinted polymer solid-phase extraction (MISPE) was investigated using a mixture of myricetin, quercetin and kaempferol. The breakthrough volumes for quercetin, kaempferol and myricetin were 22, 27 and 8 mL, respectively. The number of theoretical plates (N) for the MISPE column corresponding to these volumes were 18, 47 and 4 for quercetin, kaempferol and myricetin, respectively. Using these results, selectivity of MIP and its retention capacity was evaluated. The extractions of Moringa leaves and flowers were carried out using a MISPE cartridge and various solvents were investigated for the selective elution of quercetin from the MIP sorbents. For identification and quantification of quercetin and other flavonols, a high performance liquid chromatography (HPLC) was used. Recoveries of quercetin from different Moringa extracts ranged from 87 – 92% and this demonstrated that the MISPE method can be used for the recovery of quercetin and kaempferol from the Moringa extracts. Amount of quercetin found in Moringa leaves was 1555 mg kg-1. All the imprinted and non-imprinted polymers prepared in the study were characterized with Fourier Transform Infrared (FTIR) spectroscopy. Scanning electron microscopy (SEM) was used for recording surface morphology of all the polymers. Surface area and pore size analysis were recorded on Micromeritic Tristar BET. For quercetin MIP, thermogravimetric analysis (TGA) was also used in addition to the mentioned techniques. In additional studies, the concentrations of metals in the soil and, in the leaves and flowers of Moringa plant grown in South Africa were examined. The investigation included heavy metals, major and trace nutrient elements. The analysis of metals was achieved after total digestion of soils or leaves using a microwave, and the concentrations of metals were determined using inductively coupled plasma-optical emission spectroscopy (ICP-OES). These results were compared to those obtained from some selected vegetables like spinach, cabbage, cauliflower, broccoli, and peas. No toxic heavy metals were detected in the leaves and flowers of Moringa. On average Moringa contained higher concentration of Ca (18500 mg kg-1) and Mg (5500 mg kg-1) than other vegetables compared with in the study. Other major nutrients contained in Moringa were much similar to other vegetables. Besides metals, the concentrations of flavonols (myricetin, quercetin, kaempferol) determined from Moringa leaves and flowers were also compared to selected vegetables. Plant and vegetable materials were extracted under reflux using acidified methanol (1% HCl) solution. Following which, the flavonols were identified and quantified using reverse phased-high performance liquid chromatography method equipped with UV detection. Moringa leaves exhibited highest concentrations of myricetin (1296.6 mg kg-1), quercetin (1362.6 mg kg-1), kaempferol (1933.7 mg kg-1) than vegetables (spinach: myricetin 620.0 mg kg-1, quercetin 17.9 mg kg-1, kaempferol 215.3 mg kg-1). Lastly, the antioxidant activity of Moringa flowers and leaves were compared to that of the aforementioned selected vegetables. The antioxidant activity was studies by analyzing the total phenolic content (TPC), total flavonoid content (TFC), reducing power, radical scavenging activity, and the 2,2-diphenyl-1- picrylhydrazyl free radical (DPPH) method. Moring contained almost twice the TPC and thrice the TFC than the vegetables. Also, Moringa demonstrated higher reducing power and lower percentage of free radicals remaining (DPPH method). Hence, Moringa showed to be a good antioxidant source than the selected vegetables compared with

Application of the Baylis-Hillman reaction in the preparation of quinoline derivatives

The reaction of various 2-nitrobenzaldehyde derivatives with methyl vinyl ketone (MVK) in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) has afforded the Baylis-Hillman adducts in moderate to good yield. Dissolution of the catalyst in the solvent before the addition of the aldehyde was observed to improve the yield. Reduction of the Baylis-Hillman adducts was effected by catalytic hydrogenation using a 10% palladium-on- carbon catalyst in ethanol to give quinoline and quinoline-N-oxide derivatives and, in some cases, acyclic reduction products. All products were characterised using NMR and, where appropriate, HRMS methods. Selected quinoline-N-oxides were successfully converted to their corresponding quinoline derivatives using phosphorus tribromide (PBr₃) and DMF as solvent. Conjugate addition of the benzylamine and piperidine nucleophiles to the Baylis-Hillman adducts was also investigated but proved problematic, with one of the substrates undergoing a retro-Baylis-Hillman reaction to afford the aldehyde in ca. 40% yield, but seemingly only traces of the required product. Perkin-type coupling of two 2-methylquinolines with benzaldehyde was successfully effected to afford the desired styrylquinoline derivatives confirming the potential of the Baylis-Hillman approach to the construction of the analogues of known HIV-1 integrase inhibitors. Three ¹³C NMR chemical shift prediction programmes, viz., Chem Window, neural network and HOSE (hierarchically ordered spherical description of environment) methods were applied to selected representative compounds prepared in the project. The results from the three programmes correlated reasonably well with the experimental carbon-13 chemical shift data for each of the selected compounds

Selective removal of chromium (VI) from sulphates and other metal anions using an ion-imprinted polymer

A linear copolymer was prepared from 4-vinylpyridine and styrene. An ion-imprinted polymer (IIP) specific for Cr (VI) adsorption was prepared by copolymerisation of the quaternised linear copolymer (quaternised with 1,4-chlorobutane), 2-vinylpyridine functional monomer and ethylene glycol dimethacrylate (EGDMA), as the cross-linking monomer, in the presence of 1,1’-azobis(cyclohexanecarbonitrile) as initiator. Ammonium dichromate and aqueous methanol were used as a template and porogenic solvent, respectively. Leaching of the chromate template from the polymer particles was achieved with successive stirring of the ion-imprinted polymer (IIP) particles in 4 M HNO3 solutions to obtain leached materials, which were then used for selective rebinding of Cr (VI) ions from aqueous solutions. Similarly, the non-imprinted polymer/ control polymer (NIP/CP) material was also prepared under exactly the same conditions as the IIP but without the chromate anion template. Various parameters, such as solution pH, initial concentration, aqueous phase volume, sorbent dosage, contact time and leaching solution volumes, were investigated. Scanning electron microscopy (SEM), Fourier Transform Infrared (FTIR) spectroscopy, BET surface area and pore size analysis were used for the characterisation of IIP (both unleached and leached) and CP materials. Optimal parameters were as follows: solution pH, 3; contact time, 120 min; eluent, 20 mℓ of 0.1 M NaOH; and sorbent amount, 125 mg. Maximum retention capacity of IIP and CP was 37.58 and 25.44 mg∙g-1, respectively. The extraction efficiencies of the IIP and CP were compared using a batch and SPE mode of extraction. In the absence of high concentrations of ions, especially sulphate ions, both CP and IIP demonstrated no differences in binding of Cr (VI), which was almost 100%. However, in the presence of high concentrations of sulphate ions, the selectivity on the CP completely collapsed. The study clearly demonstrates the suitably of the developed IIP for selective extraction of Cr (VI) in complex samples such as those from acid mine drainage. The selectivity was also compared by direct injection of the real-world sample, both spiked and non-spiked, into that obtained after IIP selective extraction. Despite the method’s very low detection limits for direct injection (below 1 μg∙ℓ-1), no Cr (VI) was obtained. However, after IIP selective extraction, spiked Cr (VI) was detected in the spiked sample

Elucidation of the complex Baylis-Hillman reaction of 3-methoxy-2-nitrobenzaldehyde with methyl vinyl ketone

DABCO-catalyzed reaction of 3-methoxy-2-nitrobenzaldehyde with methyl vinyl ketone (MVK) affords a mixture of products, comprising the ‘normal’ Baylis-Hillman adduct, theMVKdimer and a pair of diastereomeric bis-(MVK)Baylis-Hillman adducts. 1HNMRspectroscopy-based kinetic studies have provided clear insights into the competing pathways and product distribution in this complex reaction

Adult antiretroviral therapy guidelines 2017

These guidelines are intended as an update to those published in the Southern African Journal of HIV Medicine in 2014 and the update on when to initiate antiretroviral therapy in 2015. Since the release of the previous guidelines, the scale-up of antiretroviral therapy (ART) in southern Africa has continued. New antiretroviral drugs have become available with improved efficacy, safety and robustness. The guidelines are intended for countries in the southern African region, which vary between lower and middle income

Why COVID-19 recovery must be gender-responsive

This summary highlights key learning from research from the Covid-19 Responses for Equity (CORE) initiative focusing on the impact the pandemic is having across different vulnerable groups and how gender intersects and often exacerbates these effects. Supported by the International Development Research Centre (IDRC), CORE brings together 21 projects to understand the socioeconomic impacts of the pandemic, improve existing responses, and generate better policy options for recovery. The research is being led primarily by local researchers, universities, thinktanks and civil society organisations across 42 countries in Africa, Asia, Latin America, and the Middle East