title: A comparative study of functional monomer and crosslinker ratios in the synthesis of  catechin-selective MIPs via suspension polymerisation

authors: Pitaduwa Gamage, Sandeepa  Thathsarani Wickramasinghe

subjects: molecularly imprinted polymers

abstract: Catechin contamination in food and environmental samples presents challenges for selective extraction and analysis, requiring advanced polymeric materials with high specificity and capacity. This study investigates the synthesis of catechin-selective molecularly imprinted polymers (MIPs) using suspension polymerisation, with a systematic evaluation of crosslinker-to-monomer (CL:M) and template-to-monomer (T:M) ratios. Polymers were prepared with CL:M ratios ranging from 1:1 to 4:1 and T:M ratios from 0 to 0.5, and characterised by particle size analysis, BET surface area and pore measurements, and scanning electron microscopy (SEM). Adsorption experiments were conducted at initial catechin concentrations of 2.5–10 mg/L, and binding isotherm models were applied to interpret the adsorption mechanisms.
Polymers synthesised at CL:M ratios of 1:1 and 2:1 with T:M = 0.125 exhibited the highest adsorption capacities, consistently achieving values above 0.080 mg/g at 10 mg/L catechin. These optimal conditions also produced polymers with yields up to 94.7%, median particle diameters between 1100–1500 μm, and average pore radii approaching 10 Å. In addition, SEM analysis revealed that optimal samples displayed uniform, spherical morphology with well-developed surface porosity, whereas non-optimal samples showed increased aggregation and denser, less accessible surfaces. Notably, the Temkin isotherm provided the best fit for the adsorption data (R² = 0.9807), indicating heterogeneous binding sites and significant adsorbate–adsorbate interactions. In contrast, higher crosslinker (CL:M= 4:1 and 3:1) or template ratios (T:M= 0.375 and 0.5) led to reduced adsorption capacity and, in some cases, persistent template leaching. These results indicate that extraction conditions must be carefully optimised, such as by increasing Soxhlet extraction time or adjusting solvent parameters, to ensure complete template removal and improve polymer performance in practical applications. Overall, these findings establish suspension polymerisation, combined with carefully optimised synthesis and extraction conditions, as an effective strategy for producing catechin-selective MIPs with enhanced selectivity, capacity, and reproducibility.

text: A comparative study of functional monomer and crosslinker ratios in the synthesis of  catechin-selective MIPs via suspension polymerisation Catechin contamination in food and environmental samples presents challenges for selective extraction and analysis, requiring advanced polymeric materials with high specificity and capacity. This study investigates the synthesis of catechin-selective molecularly imprinted polymers (MIPs) using suspension polymerisation, with a systematic evaluation of crosslinker-to-monomer (CL:M) and template-to-monomer (T:M) ratios. Polymers were prepared with CL:M ratios ranging from 1:1 to 4:1 and T:M ratios from 0 to 0.5, and characterised by particle size analysis, BET surface area and pore measurements, and scanning electron microscopy (SEM). Adsorption experiments were conducted at initial catechin concentrations of 2.5–10 mg/L, and binding isotherm models were applied to interpret the adsorption mechanisms.
Polymers synthesised at CL:M ratios of 1:1 and 2:1 with T:M = 0.125 exhibited the highest adsorption capacities, consistently achieving values above 0.080 mg/g at 10 mg/L catechin. These optimal conditions also produced polymers with yields up to 94.7%, median particle diameters between 1100–1500 μm, and average pore radii approaching 10 Å. In addition, SEM analysis revealed that optimal samples displayed uniform, spherical morphology with well-developed surface porosity, whereas non-optimal samples showed increased aggregation and denser, less accessible surfaces. Notably, the Temkin isotherm provided the best fit for the adsorption data (R² = 0.9807), indicating heterogeneous binding sites and significant adsorbate–adsorbate interactions. In contrast, higher crosslinker (CL:M= 4:1 and 3:1) or template ratios (T:M= 0.375 and 0.5) led to reduced adsorption capacity and, in some cases, persistent template leaching. These results indicate that extraction conditions must be carefully optimised, such as by increasing Soxhlet extraction time or adjusting solvent parameters, to ensure complete template removal and improve polymer performance in practical applications. Overall, these findings establish suspension polymerisation, combined with carefully optimised synthesis and extraction conditions, as an effective strategy for producing catechin-selective MIPs with enhanced selectivity, capacity, and reproducibility.

year: 2025-07-05

title: Ecological response differentials: An alternative benchmark to inform stream and river bioassessment

authors: Collier, Kevin J.

subjects: macroinvertebrate

abstract: Contemporary patterns of land development mean that suitable reference sites for low-gradient stream and non-wadeable river biomonitoring are difficult to locate, requiring alternative approaches for benchmarking human impacts. We use two strongly harmonised macroinvertebrate data sets for wadeable streams (180 sites) and non-wadeable rivers (30 sites) to (i) quantify metric response differentials across a regional landcover pressure gradient in northern New Zealand; (ii) interpolate reference condition for waterway types lacking comparable reference sites and (iii) inform development of narrative condition bands for data-poor waterway types.
Cumulative distribution functions of per cent waterway length indicated that near-shore littoral samples from non-wadeable rivers had fewer total and EPT (Ephemeroptera, Plecoptera and Trichoptera) taxa than wadeable streams, which had higher % EPT abundance and lower % Crustacea abundance. Community composition differed significantly among non-wadeable river and wadeable hard-bottom and soft-bottom stream samples, reflecting factors associated with catchment altitude, slope, rainfall and landuse intensity.
Ephemeroptera, Plecoptera and Trichoptera richness was the only metric evaluated that significantly reflected landcover across all waterway types. The intercept of the 60th percentile quantile regression line at 100% native vegetation cover provided the best approximation of median EPT taxa richness in an independent reference site data set for hard-bottom streams. Applying the same interpolation to samples from soft-bottom streams and non-wadable rivers that lacked regional reference sites indicated median reference expectations of 9 and 11 EPT taxa, respectively, and a consistent differential across the pressure gradient relative to hard-bottom streams of seven taxa and five taxa, respectively.
The derived response differentials enabled the development of narrative bands for directly comparing ecological condition of data-poor stream and river types. Quantification of ecological response differentials can provide an alternative means of benchmarking macroinvertebrate metrics in the absence of suitable reference sites.

text: Ecological response differentials: An alternative benchmark to inform stream and river bioassessment Contemporary patterns of land development mean that suitable reference sites for low-gradient stream and non-wadeable river biomonitoring are difficult to locate, requiring alternative approaches for benchmarking human impacts. We use two strongly harmonised macroinvertebrate data sets for wadeable streams (180 sites) and non-wadeable rivers (30 sites) to (i) quantify metric response differentials across a regional landcover pressure gradient in northern New Zealand; (ii) interpolate reference condition for waterway types lacking comparable reference sites and (iii) inform development of narrative condition bands for data-poor waterway types.
Cumulative distribution functions of per cent waterway length indicated that near-shore littoral samples from non-wadeable rivers had fewer total and EPT (Ephemeroptera, Plecoptera and Trichoptera) taxa than wadeable streams, which had higher % EPT abundance and lower % Crustacea abundance. Community composition differed significantly among non-wadeable river and wadeable hard-bottom and soft-bottom stream samples, reflecting factors associated with catchment altitude, slope, rainfall and landuse intensity.
Ephemeroptera, Plecoptera and Trichoptera richness was the only metric evaluated that significantly reflected landcover across all waterway types. The intercept of the 60th percentile quantile regression line at 100% native vegetation cover provided the best approximation of median EPT taxa richness in an independent reference site data set for hard-bottom streams. Applying the same interpolation to samples from soft-bottom streams and non-wadable rivers that lacked regional reference sites indicated median reference expectations of 9 and 11 EPT taxa, respectively, and a consistent differential across the pressure gradient relative to hard-bottom streams of seven taxa and five taxa, respectively.
The derived response differentials enabled the development of narrative bands for directly comparing ecological condition of data-poor stream and river types. Quantification of ecological response differentials can provide an alternative means of benchmarking macroinvertebrate metrics in the absence of suitable reference sites.

year: 2013

title: Editorial for “Unmasking Racism and Oppression in Psychology” – Part II

authors: Tan, Kyle K. H.

abstract: Since publishing the first part of the “Unmasking Racism and Oppression in Psychology” special issue in March 2025, we have received immense aroha and gratitude from colleagues and students eager to learn about the perspectives of Indigenous and minoritised groups in psychology and how they can support the development of an anti-racist discipline. Rather than seeking to prove the existence of racism in the field (Crossing et al., 2024), this issue centres on validating our authors’ experiences of navigating oppression, challenging Eurocentric psychology, resisting assimilation, and remaining grounded in Indigenous ontologies and epistemologies while staying accountable to their communities. Racism in psychology has been called out by many colleagues in Aotearoa (to name a few; Levy & Waitoki, 2016; Love, 2008; Pomare et al., 2021), and this issue responds to their concerns by amplifying solutions for change in the teaching, practice, and research of psychology.

text: Editorial for “Unmasking Racism and Oppression in Psychology” – Part II Since publishing the first part of the “Unmasking Racism and Oppression in Psychology” special issue in March 2025, we have received immense aroha and gratitude from colleagues and students eager to learn about the perspectives of Indigenous and minoritised groups in psychology and how they can support the development of an anti-racist discipline. Rather than seeking to prove the existence of racism in the field (Crossing et al., 2024), this issue centres on validating our authors’ experiences of navigating oppression, challenging Eurocentric psychology, resisting assimilation, and remaining grounded in Indigenous ontologies and epistemologies while staying accountable to their communities. Racism in psychology has been called out by many colleagues in Aotearoa (to name a few; Levy & Waitoki, 2016; Love, 2008; Pomare et al., 2021), and this issue responds to their concerns by amplifying solutions for change in the teaching, practice, and research of psychology.

year: 2025