Microchip-based small, dense low-density lipoproteins assay for coronary heart disease risk assessment

Microfluidic-based cardiovascular systems for advanced study of atherosclerosis

Atherosclerosis (AS) is a significant global health concern due to its high morbidity and mortality rates. Extensive efforts have been made to replicate the cardiovascular system and explore the pathogenesis, diagnosis, and treatment of AS. Microfluidics has emerged as a valuable technology for modeling the cardiovascular system and studying AS. Here a brief review of the advances of microfluidic-based cardiovascular systems for AS research is presented. The critical pathogenetic mechanisms of AS investigated by microfluidic-based cardiovascular systems are categorized and reviewed, with a detailed summary of accurate diagnostic methods for detecting biomarkers using microfluidics represented. Furthermore, the review covers the evaluation and screening of AS drugs assisted by microfluidic systems, along with the fabrication of novel drug delivery carriers. Finally, the challenges and future prospects for advancing microfluidic-based cardiovascular systems in AS research are discussed and proposed, particularly regarding new opportunities in multi-disciplinary fundamental research and therapeutic applications for a broader range of disease treatments.

A decade of microchip electrophoresis for clinical diagnostics - A review of 2008-2017

A core element in clinical diagnostics is the data interpretation obtained through the analysis of patient samples. To obtain relevant and reliable information, a methodological approach of sample preparation, separation, and detection is required. Traditionally, these steps are performed independently and stepwise. Microchip capillary electrophoresis (MCE) can provide rapid and high-resolution separation with the capability to integrate a streamlined and complete diagnostic workflow suitable for the point-of-care setting. Whilst standard clinical diagnostics methods normally require hours to days to retrieve specific patient data, MCE can reduce the time to minutes, hastening the delivery of treatment options for the patients. This review covers the advances in MCE for disease detection from 2008 to 2017. Miniaturised diagnostic approaches that required an electrophoretic separation step prior to the detection of the biological samples are reviewed. In the two main sections, the discussion is focused on the technical set-up used to suit MCE for disease detection and on the strategies that have been applied to study various diseases. Throughout these discussions MCE is compared to other techniques to create context of the potential and challenges of MCE. A comprehensive table categorised based on the studied disease using MCE is provided. We also comment on future challenges that remain to be addressed.

Small dense low density lipoprotein-cholesterol and cholesterol ratios to predict arterial stiffness progression in normotensive subjects over a 5-year period

BACKGROUND

Small dense low density lipoprotein-cholesterol (sdLDL-C), cholesterol ratios and carotid-femoral pulse wave velocity (cf-PWV) impart risk for all-cause morbidity and mortality independently of conventional cardiovascular disease (CVD) risk factors. This study was designed to identify feasible indicators for predicting arterial stiffness progression.

METHODS

We followed up 816 normotensive participants without diabetes or CVD for nearly 5.0 years. Cholesterol parameters, ratios and other clinical and laboratory data were collected at baseline. cf-PWV were measured at baseline and the end of follow-up.

RESULTS

PWV progression subjects had higher levels of PWV parameters, sdLDL-C and TG/HDL-C ratio. sdLDL-C and TG/HDL-C were significantly correlated with all PWV parameters. Multiple regression models showed that sdLDL-C was closely associated with follow-up PWV (β = 0.222, p < 0.001) and △PWV (β = 0.275, p < 0.001). TG/HDL-C was only one cholesterol ratios that associated with all PWV parameters. sdLDL-C (OR = 2.070, 95%CI: 1.162 to 3.688, p = 0.014) and TG/HDL-C (OR = 1.355, 95%CI: 1.136 to 1.617, p = 0.001) could significantly determine the progression of PWV after correction for covariates. High sd-LDL-C quantiles subjects were more likely to develop arterial stiffness progression than low quantiles (Tertiles 3 vs Tertiles1, RR = 2.867, 95%CI: 1.106 to 7.434, p = 0.03).

CONCLUSION

We founded that sdLDL-C and TG/HDL-C ratio can independently predict arterial stiffness progression in normotensive subjects, and high level sdLDL-C and TG/HDL-C ratio were associated with a higher risk of arterial stiffness.

Simplified microchip electrophoresis for rapid separation of urine proteins

BACKGROUND

Urine protein test has been widely used in clinics, but to determine the type of proteinuria is usually difficult due to technical limitations.

METHODS

In the current study, a rapid and simple method to separate and determine urine proteins by a microchip electrophoresis (ME) system has been developed in which only 4 min are required.

RESULTS

Optimal separation conditions have been established by using 15 s injection time at 500 and 1,500 V separation voltage in 75 mmol/l borate buffer containing 0.8 mmol/l calcium lactate and 1% ϕ ethylamine (pH 10.55). Relative standard deviation (RSD) of migration time with purified human albumin and human transferring was 2.68% and 2.24%, and RSD of the peak area was 5.85% and 4.96%, respectively. The linear detection range was 1.0-15.0 g/l for purified human albumin and 1.0-10.0 g/l for human transferrin, with the same detection limit (S/N = 3) of 0.4 g/l. Finally, comparing to conventional agarose gel electrophoresis, the same results were obtained by using ME by testing clinical samples including 60 selective proteinuria, 105 nonselective proteinuria, and 6 overflow proteinuria.

CONCLUSION

This newly established ME could have broad applications to determine the type of proteinuria in clinics.

Fraction estimation of small, dense LDL using autocorrelation function of dynamic light scattering

Small, dense low-density lipoprotein (sdLDL) in total LDL is strongly related with the cardiovascular risk level. An optical technique using dynamic light scattering (DLS) measurement is useful for point-of-care testing of sdLDL. However, the sdLDL fraction estimated from the particle size distribution in DLS data is sensitive to noise and artifacts. Therefore, we derived analytical solutions in a closed form to estimate the fraction of scatterers using the autocorrelation function of scattered light from a polydisperse solution. The effect of the undesired large particles can be eliminated by the pre-processing of the autocorrelation function. The proposed technique was verified using latex standard particles and LDL solutions. Results suggest the feasibility of this technique to estimate the sdLDL fraction using optical scattering measurements.

Partial filling affinity capillary electrophoresis with cationic poly(vinylpyrrolidone)-based copolymer coatings for studies on human lipoprotein-steroid interactions

Human plasma lipoproteins have strong hydrophobic interactions with steroids and their fatty acyl derivatives such as estradiol fatty acyl esters. In this work, affinity capillary electrophoresis with the partial filling technique was applied to study the hydrophobic interactions between lipoproteins, which are nanometer-sized particles, and nonconjugated steroids. The capillaries were first rinsed with one of two novel poly(vinylpyrrolidone) (PVP)-based cationic copolymers that were strongly adsorbed onto the fused-silica surface via electrostatic interactions. This surface treatment greatly suppressed the adsorption of lipoproteins. Low-density lipoprotein (LDL) and high-density lipoprotein (HDL) particles were then employed in the coated capillaries as pseudostationary phase in the partial filling mode. The changes in corrected migration times of steroids increased linearly with the filling time of the lipoproteins. The affinity constants between the steroids and lipoproteins were calculated, and the most hydrophobic steroid studied, progesterone, had stronger affinity than testosterone or androstenedione toward both LDL and HDL. Affinity between steroids and LDL was stronger than that between steroids and HDL. Interactions between the steroids and lipoproteins were mainly nonspecific with particle lipid components, whereas some were site specific with the apolipoproteins. The developed technique has great potential for determination of the affinity of various compounds toward lipoproteins.

Application of poly(dimethylsiloxane)/glass microchip for fast electrophoretic separation of serum small, dense low-density lipoprotein

Due to the mounting evidence of altered low-density lipoprotein (LDL) size in several disease states, there has been an increasing interest in developing new analytical methods for small, dense low-density lipoprotein (sdLDL) for diagnosis. The present report demonstrates that sdLDL analysis can be performed in a poly(dimethylsiloxane) (PDMS/glass) microchannel. n-Dodecyl beta-D-maltoside (DDM) was utilized to alter channel surface to make it become hydrophilic and nonionic, thus reducing the interaction between the protein and the surface. Moreover, hydroxypropylcellulose (HPC) was added into the running buffer to suppress the adsorption of analytes and also to serve as a sieving matrix. Under optimal conditions, two baseline separations of lipoproteins including high-density lipoprotein (HDL), sdLDL, and lLDL were achieved with different selectivity. LDL particles shown on the electropherogram were also identified by several procedures. This method affords high separation speed and high reproducibility. The intraassay and interassay RSDs of lipoprotein migration times were in the range of 2.01-2.45%. The variation of serum sdLDL of a patient between prior treatment and post-treatment was assessed by this method. This system has the potential for rapid and sensitive detection of different LDL forms, and thus will be applicable to clinical diagnosis.