Population of SPION@SiO 2 nanoparticles refers to the percentage of the total measured population of particles which exist as single-core@shell particles. The regression analysis of population of SPION@SiO 2 NPs was performed using the data collected from TEM analysis (Table and Table , ESI †). The regression model correlation coefficient (r 2 ) was 0.32, indicating that the experi-Table Parameter estimates deemed to be active in effecting the population of SPION@SiO 2 formed. The parameter estimates were calculated from the regression analysis and used in the prediction expression. In the case below, the number of moles of TEOS and number of moles of NH 4 OH are still included as a parameter they are active in the (TEOS-1.43 The prediction expression for population, as determined by regression analysis, is given by: Pop. = 51.97 + 1.80