MIP-based protein profiling: A method for interspecies discrimination

Due to recent public concern and interest in the authenticity and origin of meat, for example, the 2013 “horsemeat scandal” in the human food chain, novel sensor strategies for the discrimination between protein species are highly sought after. In this work, molecularly imprinted polymers (MIPs) are utilised for protein discrimination using electrochemical sensor and spectrophotometric techniques. MIP selectivity between two proteins of similar molecular weight (haemoglobin and serum albumin) were compared across three different species, namely pork, beef and human. Bulk MIPs resulted in Kd and Bmax values of 184±23 µM, and 582 µmol g-1 for BHb, 246.3±26 µM, and 673 µmol g-1 for HHb; 276±31 µM, and 467 µmol g-1 for PHb. With the aid of chemometrics, i.e. multivariate analysis and pattern recognition, distinctive protein profiles have been achieved for species discrimination in both spectrophotometric and electrochemical analysis experiments. MIP suitability and selectivity within complex matrices was also assessed using urine, human plasma and human serum. Pattern recognition MIP-based protein profiling demonstrated positive outputs yielding either a ‘bovine’ or ‘not-bovine’ outcome (p = 0.0005) for biological samples spiked with/without bovine using respective bovine haemoglobin MIPs

Highly selective BSA imprinted polyacrylamide hydrogels facilitated by a metal-coding MIP approach

We report the fabrication of metal-coded molecularly imprinted polymers (MIPs) using hydrogel-based protein imprinting techniques. A Co(II) complex was prepared using (E)-2-((2 hydrazide-(4-vinylbenzyl) hydrazono)methyl)phenol; along with iron(III) chloroprotoporphyrin (Hemin), vinylferrocene (VFc), zinc (II) protoporphyrin (ZnPP) and protoporphyrin (PP), these complexes were introduced into the MIPs as co-monomers for metal-coding of non-metalloprotein imprints. Results indicate a 66% enhancement for bovine serum albumin (BSA) protein binding capacities (Q, mg/g) via metal-ion/ligand exchange properties within the metal-coded MIPs. Specifically, Co(II)-complex-based MIPs exhibited 92 ± 1% specific binding with Q values of 5.7 ± 0.45 mg BSA/g polymer and imprinting factors (IF) of 14.8 ± 1.9 (MIP/non-imprinted (NIP) control). The selectivity of our Co(II)-coded BSA MIPs were also tested using bovine haemoglobin (BHb), lysozyme (Lyz), and trypsin (Tryp). By evaluating imprinting factors (K), each of the latter proteins was found to have lower affinities in comparison to cognate BSA template. The hydrogels were further characterised by thermal analysis and differential scanning calorimetry (DSC) to assess optimum polymer composition

Evaluation of electropolymerized molecularly imprinted polymers (E-MIPs) on disposable electrodes for detection of SARS-CoV-2 in saliva

We investigate electropolymerized molecularly imprinted polymers (E-MIPs) for the selective recognition of SARS-CoV-2 whole virus. E-MIPs imprinted with SARS-CoV-2 pseudoparticles (pps) were electrochemically deposited onto screen printed electrodes by reductive electropolymerization, using the water-soluble N-hydroxmethylacrylamide (NHMA) as functional monomer and crosslinked with N,N′-methylenebisacrylamide (MBAm). E-MIPs for SARS-CoV-2 showed selectivity for template SARS-CoV-2 pps, with an imprinting factor of 3:1, and specificity (significance = 0.06) when cross-reacted with other respiratory viruses. E-MIPs detected the presence of SARS-CoV-2 pps in <10 min with a limit of detection of 4.9 log10 pfu/mL, suggesting their suitability for detection of SARS-CoV-2 with minimal sample preparation. Using electrochemical impedance spectroscopy (EIS) and principal component analysis (PCA), the capture of SARS-CoV-2 from real patient saliva samples was also evaluated. Fifteen confirmed COVID-19 positive and nine COVID-19 negative saliva samples were compared against the established loop-mediated isothermal nucleic acid amplification (LAMP) technique used by the UK National Health Service. EIS data demonstrated a PCA discrimination between positive and negative LAMP samples. A threshold real impedance signal (ZRe) ≫ 4000 Ω and a corresponding charge transfer resistance (RCT) ≫ 6000 Ω was indicative of absence of virus (COVID-19 negative) in agreement with values obtained for our control non-imprinted polymer control. A ZRe at or below a threshold value of 600 Ω with a corresponding RCT of <1200 Ω was indicative of a COVID-19 positive sample. The presence of virus was confirmed by treatment of E-MIPs with a SARS-CoV-2 specific monoclonal antibody

Mapping geographical inequalities in childhood diarrhoeal morbidity and mortality in low-income and middle-income countries, 2000–17 : analysis for the Global Burden of Disease Study 2017

Background Across low-income and middle-income countries (LMICs), one in ten deaths in children younger than 5 years is attributable to diarrhoea. The substantial between-country variation in both diarrhoea incidence and mortality is attributable to interventions that protect children, prevent infection, and treat disease. Identifying subnational regions with the highest burden and mapping associated risk factors can aid in reducing preventable childhood diarrhoea. Methods We used Bayesian model-based geostatistics and a geolocated dataset comprising 15 072 746 children younger than 5 years from 466 surveys in 94 LMICs, in combination with findings of the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2017, to estimate posterior distributions of diarrhoea prevalence, incidence, and mortality from 2000 to 2017. From these data, we estimated the burden of diarrhoea at varying subnational levels (termed units) by spatially aggregating draws, and we investigated the drivers of subnational patterns by creating aggregated risk factor estimates. Findings The greatest declines in diarrhoeal mortality were seen in south and southeast Asia and South America, where 54·0% (95% uncertainty interval [UI] 38·1–65·8), 17·4% (7·7–28·4), and 59·5% (34·2–86·9) of units, respectively, recorded decreases in deaths from diarrhoea greater than 10%. Although children in much of Africa remain at high risk of death due to diarrhoea, regions with the most deaths were outside Africa, with the highest mortality units located in Pakistan. Indonesia showed the greatest within-country geographical inequality; some regions had mortality rates nearly four times the average country rate. Reductions in mortality were correlated to improvements in water, sanitation, and hygiene (WASH) or reductions in child growth failure (CGF). Similarly, most high-risk areas had poor WASH, high CGF, or low oral rehydration therapy coverage. Interpretation By co-analysing geospatial trends in diarrhoeal burden and its key risk factors, we could assess candidate drivers of subnational death reduction. Further, by doing a counterfactual analysis of the remaining disease burden using key risk factors, we identified potential intervention strategies for vulnerable populations. In view of the demands for limited resources in LMICs, accurately quantifying the burden of diarrhoea and its drivers is important for precision public health

Mapping local patterns of childhood overweight and wasting in low- and middle-income countries between 2000 and 2017

A double burden of malnutrition occurs when individuals, household members or communities experience both undernutrition and overweight. Here, we show geospatial estimates of overweight and wasting prevalence among children under 5 years of age in 105 low- and middle-income countries (LMICs) from 2000 to 2017 and aggregate these to policy-relevant administrative units. Wasting decreased overall across LMICs between 2000 and 2017, from 8.4 (62.3 (55.1�70.8) million) to 6.4 (58.3 (47.6�70.7) million), but is predicted to remain above the World Health Organization�s Global Nutrition Target of <5 in over half of LMICs by 2025. Prevalence of overweight increased from 5.2 (30 (22.8�38.5) million) in 2000 to 6.0 (55.5 (44.8�67.9) million) children aged under 5 years in 2017. Areas most affected by double burden of malnutrition were located in Indonesia, Thailand, southeastern China, Botswana, Cameroon and central Nigeria. Our estimates provide a new perspective to researchers, policy makers and public health agencies in their efforts to address this global childhood syndemic. © 2020, The Author(s)

Author Correction: Mapping local patterns of childhood overweight and wasting in low- and middle-income countries between 2000 and 2017 (Nature Medicine, (2020), 26, 5, (750-759), 10.1038/s41591-020-0807-6)

An amendment to this paper has been published and can be accessed via a link at the top of the paper. © 2020, The Author(s)

Author Correction: Mapping local patterns of childhood overweight and wasting in low- and middle-income countries between 2000 and 2017 (Nature Medicine, (2020), 26, 5, (750-759), 10.1038/s41591-020-0807-6)

An amendment to this paper has been published and can be accessed via a link at the top of the paper. © 2020, The Author(s)

Smart materials : towards on-site detection of biomacromolecules using hydrogel-based molecularly imprinted polymers.

The use of bio-mimetic receptor systems have been considered in a quest for affinities and specificities that are on a par with natural receptors for rapid in-situ analysis based on coupled-sensor techniques. The work describes the experimental optimisation and characterisation of hydrogel-based molecularly imprinted polymers (MIPs) for a range of proteins and pathogens, including plant viruses. A variety of acrylamide-based functional monomers, along with several integrated metal complexes for signal transduction have been exploited in the fabrication of both bulk and surface imprinting of MIPs. Spectrophotochemical, electrochemical and quartz crystal microbalance (QCM) analytical techniques were utilised for quantifying imprinting effects by assessing specific and/or non-specific binding. Bulk imprinting exhibited high selectivities (rebinding efficiencies ≈ 80%) and imprinting factors of ≈ 14 (MIP/NIP ratio) across varied templates. MIP-coupled QCM sensors illustrated binding and elution of target proteins through distinct frequency and impedance transitions at 3 mg mL-1. QCM surface imprinting via electrochemically-induced polymerisation (ECIP) was less successful. Whereas electrochemical ECIP methods using glassy carbon electrodes (GCEs) illustrated good compatibility, higher sensitivities, and a limit of detection (LOD) of 16 μg mL-1 and a limit of quantification (LOQ) of 56 μg mL-1 for BHb. Pattern recognition techniques using multivariate analysis were also implemented to reduce complex data sets. Principle component analysis (PCA) and linear discriminant analysis (LDA) techniques illustrated unique binding pattern profiles depending on the sample matrix analysed, significance (ρ) ≤ 0.0005. The latter ECIP methods were also transposed onto disposable screen-printed carbon electrodes (SPCEs) based on the introduction of redox tracers (both externally and within the MIP matrix). SPCEs offer an attractive opportunity for the development of miniaturised low cost electrochemical sensors. However, several complications arose and little sensitivity was observed in terms of MIP binding. Once fully developed, the benefits of sensitivity, specificity and stability of MIPs coupled with discriminatory sensor techniques, as described here, could be crucial to the future impact of portable diagnostics for personal healthcare and use by health professionals. This technology also presents major potential benefits to environmental and food monitoring as it could provide an inexpensive, fast, and efficient diagnostic method for highly sensitive analytical procedures

Smart materials : towards on-site detection of biomacromolecules using hydrogel-based molecularly imprinted polymers.

The use of bio-mimetic receptor systems have been considered in a quest for affinities and specificities that are on a par with natural receptors for rapid in-situ analysis based on coupled-sensor techniques. The work describes the experimental optimisation and characterisation of hydrogel-based molecularly imprinted polymers (MIPs) for a range of proteins and pathogens, including plant viruses. A variety of acrylamide-based functional monomers, along with several integrated metal complexes for signal transduction have been exploited in the fabrication of both bulk and surface imprinting of MIPs. Spectrophotochemical, electrochemical and quartz crystal microbalance (QCM) analytical techniques were utilised for quantifying imprinting effects by assessing specific and/or non-specific binding. Bulk imprinting exhibited high selectivities (rebinding efficiencies ≈ 80%) and imprinting factors of ≈ 14 (MIP/NIP ratio) across varied templates. MIP-coupled QCM sensors illustrated binding and elution of target proteins through distinct frequency and impedance transitions at 3 mg mL-1. QCM surface imprinting via electrochemically-induced polymerisation (ECIP) was less successful. Whereas electrochemical ECIP methods using glassy carbon electrodes (GCEs) illustrated good compatibility, higher sensitivities, and a limit of detection (LOD) of 16 μg mL-1 and a limit of quantification (LOQ) of 56 μg mL-1 for BHb. Pattern recognition techniques using multivariate analysis were also implemented to reduce complex data sets. Principle component analysis (PCA) and linear discriminant analysis (LDA) techniques illustrated unique binding pattern profiles depending on the sample matrix analysed, significance (ρ) ≤ 0.0005. The latter ECIP methods were also transposed onto disposable screen-printed carbon electrodes (SPCEs) based on the introduction of redox tracers (both externally and within the MIP matrix). SPCEs offer an attractive opportunity for the development of miniaturised low cost electrochemical sensors. However, several complications arose and little sensitivity was observed in terms of MIP binding. Once fully developed, the benefits of sensitivity, specificity and stability of MIPs coupled with discriminatory sensor techniques, as described here, could be crucial to the future impact of portable diagnostics for personal healthcare and use by health professionals. This technology also presents major potential benefits to environmental and food monitoring as it could provide an inexpensive, fast, and efficient diagnostic method for highly sensitive analytical procedures

Electrochemical detection of dioctyl phthalate using molecularly imprinted polymer modified screen-printed electrodes

We report the investigation of electropolymerised molecularly imprinted polymers (E-MIPs) for the determination of dioctyl phthalate (DOP). Low-cost and eco-friendly commercially available screen-printed electrodes (SPEs) were used. E-MIPs were produced using the cyclic voltammetry (CV) technique based on a water-soluble 4-aminophenol as functional monomer. E-MIPs for DOP showed affinity for the template, with 80% binding efficiency and an imprinting factor of 3. The E-MIPs were able to detect absolute levels of DOP in a time-dependent adsorption manner with the presence of 250 μg DOP (equivalent to 12.8 μM) detected in 5 min with a LOD (at 15 min) of 177.1 μg and LOQ of 536.6 μg making them suitable for the measurement of DOP in freshwater when the sample is pre-concentrated