Preparation, characterization, and optimization of primaquine-loaded solid lipid nanoparticles

Wesley Nyaigoti Omwoyo,1,2 Bernhards Ogutu,3,4 Florence Oloo,3,5 Hulda Swai,6 Lonji Kalombo,6 Paula Melariri,6 Geoffrey Maroa Mahanga,2 Jeremiah Waweru Gathirwa3,4 1Department of Chemistry, Maasai Mara University, Narok, Kenya; 2Department of Chemistry, Jaramogi Oginga Odinga University of Science and Technology, Bondo, Kenya; 3Center for Research in Therapeutic Sciences, Strathmore University, Nairobi, Kenya; 4Kenya Medical Research Institute, Nairobi, Kenya; 5Department of Chemical Sciences and Technology, Technical University of Kenya, Nairobi, Kenya; 6Department of Polymers and Composites, Council for Scientific and Industrial Research, Pretoria, South Africa Abstract: Primaquine (PQ) is one of the most widely used antimalarial drugs and is the only available drug that combats the relapsing form of malaria. PQ use in higher doses is limited by severe tissue toxicity including hematological- and gastrointestinal-related side effects. Nanoformulation of drugs in an appropriate drug carrier system has been extensively studied and shown to have the potential to improve bioavailability, thereby enhancing activity, reducing dose frequency, and subsequently reducing toxicity. The aim of this work was to design, synthesize, and characterize PQ-loaded solid lipid nanoparticles (SLNs) (PQ-SLNs) as a potential drug-delivery system. SLNs were prepared by a modified solvent emulsification evaporation method based on a water-in-oil-in-water (w/o/w) double emulsion. The mean particle size, zeta potential, drug loading, and encapsulation efficiency of the PQ-SLNs were 236 nm, +23 mV, 14%, and 75%, respectively. The zeta potential of the SLNs changed dramatically, from -6.54 mV to +23.0 mV, by binding positively charged chitosan as surface modifier. A spherical morphology of PQ-SLNs was seen by scanning electron microscope. In vitro, release profile depicted a steady drug release over 72 hours. Differential scanning calorimeter thermograms demonstrated presence of drug in drug-loaded nanoparticles along with disappearance of decomposition exotherms, suggesting increased physical stability of drug in prepared formulations. Negligible changes in characteristic peaks of drug in Fourier transform infrared spectra indicated absence of any interaction among the various components entrapped in the nanoparticle formulation. The nanoformulated PQ was 20% more effective as compared with conventional oral dose when tested in Plasmodium berghei-infected Swiss albino mice. This study demonstrated an efficient method of forming a nanomedicine delivery system for antimalarial drugs. Keywords: double emulsion, nanomedicine drug-delivery system, antimalarial, nanotechnolog

The effectiveness of mathematics teaching: a cross-national investigation in primary schools in England and China

This study focuses on the effectiveness of mathematics teaching to children aged 9-10 years, applies a mixture of six methods to classroom-level data collected in England and China, correlates observable teacher behaviours with pupil mathematics performance and collects multiple perceptions that indirectly connect with the differences of teaching and learning cross-nationally. It has been found in the study that 9-to 10-year-olds (n = 343) from China outscored their English peers (n = 236) at the same age by over 20 per cent in each of two mathematics tests derived from TIMSS 2003. Structured analysis of lesson videos has revealed that Chinese mathematics teachers scored much higher than their English colleagues on an internationally validated observation instrument which focused on the quality of six dimensions of teacher behaviours. Furthermore, the quantity of teacher behaviours was also measured and the subsequent correlational analysis on pooled data indicated a positive effect of whole-class interactive teaching (r = 0.97, p < 0.01) and pupil time on task (r = 0.95, p < 0.01) and a negative impact of whole-class lecture (r = -0.91, p < 0.01), individual/group work (r=-0.81, p < 0.05) and classroom management (r = -0.77, p < 0.05) on pupils’ mathematics performance cross-nationally. Qualitative findings are connected with quantitative results to explain how teachers think, how this relates to the way they teach and how the differences of teaching result in the performance gap cross-nationally. The study replicated previous TER findings from the West across two geographically and culturally different countries, suggested possible directions for future enquiries, and recommended potential ways for practice and policy innovations