Dopamine-loaded liposome and its application in electrochemical DNA biosensor

Synthetic Cells from Droplet-Based Microfluidics for Biosensing and Biomedical Applications

Synthetic cells function as biological mimics of natural cells by mimicking salient features of cells such as metabolism, response to stimuli, gene expression, direct metabolism, and high stability. Droplet-based microfluidic technology presents the opportunity for encapsulating biological functional components in uni-lamellar liposome or polymer droplets. Verified by its success in the fabrication of synthetic cells, microfluidic technology is widely replacing conventional labor-intensive, expensive, and sophisticated techniques justified by its ability to miniaturize and perform batch production operations. In this review, an overview of recent research on the preparation of synthetic cells through droplet-based microfluidics is provided. Different synthetic cells including lipid vesicles (liposome), polymer vesicles (polymersome), coacervate microdroplets, and colloidosomes, are systematically discussed. Efforts are then made to discuss the design of a variety of microfluidic chips for synthetic cell preparation since the combination of microfluidics with bottom-up synthetic biology allows for reproductive and tunable construction of batches of synthetic cell models from simple structures to higher hierarchical structures. The recent advances aimed at exploiting them in biosensors and other biomedical applications are then discussed. Finally, some perspectives on the challenges and future developments of synthetic cell research with microfluidics for biomimetic science and biomedical applications are provided.

Recent advancements in biosensor designs toward the detection of intestine cancer miRNA biomarkers

Cancer diagnosis and treatment have been of broad interest among scientists in the last decades due to the high death rate, widespread occurrence, and recurrence after treatment. The survival rate of cancer patients depends greatly on early detection and appropriate treatments. Therefore developing new technologies applicable to sensitive and specific methods of cancer detection is an inevitable task for cancer researchers. Abnormal miRNA expression is contributed to severe diseases such as cancers and since their expression level and type differ strictly during carcinogenesis and later metastasis and treatments, the improved detection accuracy of these miRNAs would undoubtedly lead to early diagnosis, prognosis, and targeted therapy. Biosensors are accurate and straightforward analytical devices that have had practical applications especially in the last decade. Their domain is still growing through a combination of attractive nanomaterials and amplification methods, leading to innovative biosensing platforms for the efficient detection of miRNAs as diagnostic and prognostic biomarkers. In this review, we will provide the recent developments in biosensors to detect intestine cancer miRNA biomarkers and also discuss the challenges and outcomings of this field.

Overview on the Design of Magnetically Assisted Electrochemical Biosensors

Electrochemical biosensors generally require the immobilization of recognition elements or capture probes on the electrode surface. This may limit their practical applications due to the complex operation procedure and low repeatability and stability. Magnetically assisted biosensors show remarkable advantages in separation and pre-concentration of targets from complex biological samples. More importantly, magnetically assisted sensing systems show high throughput since the magnetic materials can be produced and preserved on a large scale. In this work, we summarized the design of electrochemical biosensors involving magnetic materials as the platforms for recognition reaction and target conversion. The recognition reactions usually include antigen-antibody, DNA hybridization, and aptamer-target interactions. By conjugating an electroactive probe to biomolecules attached to magnetic materials, the complexes can be accumulated near to an electrode surface with the aid of external magnet field, producing an easily measurable redox current. The redox current can be further enhanced by enzymes, nanomaterials, DNA assemblies, and thermal-cycle or isothermal amplification. In magnetically assisted assays, the magnetic substrates are removed by a magnet after the target conversion, and the signal can be monitored through stimuli-response release of signal reporters, enzymatic production of electroactive species, or target-induced generation of messenger DNA.

Development of novel aptasensor for ultra-sensitive detection of myoglobin via electrochemical signal amplification of methylene blue using poly (styrene)-block-poly (acrylic acid) amphiphilic copolymer

Amplification of electrochemical signal in order to betterment of limit of detection in determination of biomarkers has an important role in early detection of some dangerous diseases such as cancers. For this purpose, in this research, two types of poly (styrene)-block-poly (acrylic acid) amphiphilic copolymer (PS₆₁-b-PAA₅₉₆ and PS₅₉₆-b-PAA₆₁) were synthesized by controlled radical polymerization method via reversible addition-fragmentation chain transfer polymerization (RAFT) technique. Chemical structure of block copolymers was confirmed by FT-IR spectroscopy and their surface morphology was assessed by scanning electron microscopy (SEM). Self-assembly of these block copolymers into polymeric vesicles (polymersomes), loading and release efficiency of methylene blue as an electroactive indicator were investigated in DMF and THF solvents. On the basis of our findings PS₆₁-b-PAA₅₉₆ has better capability for loading and release of MB than PS₅₉₆-b-PAA₆₁. Then the obtained methylene blue-loaded polymersome successfully used for development of an aptasensor toward determination of trace amounts of myoglobin. The proposed aptasensor showed a wide linear range from 1.0 aM to 1.0 μM with an ultra-low detection limit of 0.73 aM. Applying this amplification strategy, determination of myoglobin in real samples was successfully performed.

Synthesis of chitosan-grafted poly-acrylic acid (CTS-g-PAA) hydrogel and its potential application in biosensors for signal enhancing and bioanalysis

Nowadays, hydrogels have been attracted a lot of interest due to their immense potential in different fields such as biomedicine and biotechnology. Biodegradable and biocompatible pH-sensitive chitosan-grafted polyacrylic acid (CTS-g-PAA) hydrogel was synthesized by grafting an acrylic acid monomer onto chitosan at the presence of methylene bisacrylamide as a cross-linking agent and ammonium persulphate as an initiator. FT-IR spectroscopy and scanning electron microscopy (SEM) were used to analyze the properties of the obtained hydrogel. The synthesized hydrogel is suitable for the delivery of many hydrophilic drugs or species. Using a multi-walled carbon nanotube modified-glassy carbon electrode (CNT-GCE), the loading and release conditions of Nile Blue (NB) as an electroactive compound were evaluated utilizing the differential pulse voltammetry (DPV) and cyclic voltammetry (CV). The effect of various parameters on the electrochemical signal of NB was investigated, and the optimal conditions for the efficient performance of hydrogel to delivery of NB were obtained. The electrocatalytic current values show linear dependence to NB concentration in the range of 0.098 - 0.971 μM while the detection limit of this electrochemical platform was 12.3 nM. The unique proposed hydrogel with the electroactive NB has a broad range of possible applications in biosensors for signal enhancement and bioanalysis.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10854-021-06939-7.

In vitro investigations on dopamine loaded Solid Lipid Nanoparticles

The progressive degeneration of nigrostriatal neurons leads to depletion of the neurotransmitter dopamine (DA) in Parkinson's disease (PD). The hydrophilicity of DA, hindering its cross of the Blood Brain Barrier, makes impossible its therapeutic administration. This work aims at investigating some physicochemical features of novel Solid Lipid Nanoparticles (SLN) intended to enhance DA brain delivery for PD patients by intranasal administration. For this aim, novel SLN were formulated in the presence of Glycol Chitosan (GCS), and it was found that SLN containing GCS and DA were smaller than DA-loaded SLN, endowed with a slightly positive zeta potential value and, remarkably, incorporated 81 % of the initial DA content. The formulated SLN were accurately characterized by Infrared Spectroscopy in Attenuated Total Reflectance mode (FT-IT/ATR) and Thermogravimetric Analysis (TGA) to highlight SLN solid-state properties as a preliminary step forward biological assay. Overall, in vitro characterization shows that SLN are promising for DA incorporation and stable from a thermal viewpoint. Further studies are in due course to test their potential for PD treatment.

Amperometric Detection of Conformational Change of Proteins Using Immobilized-Liposome Sensor System

An immobilized liposome electrode (ILE)-based sensor was developed to quantify conformational changes of the proteins under various stress conditions. The ILE surface was characterized by using a tapping-mode atomic force microscopy (TM-AFM) to confirm surface immobilization of liposome. The uniform layer of liposome was formed on the electrode. The current deviations generated based on the status of the proteins under different stress were then measured. Bovine carbonic anhydrase (CAB) and lysozyme were tested with three different conditions: native, reduced and partially denatured. For both proteins, a linear dynamic range formed between denatured concentrations and output electric current signals was able to quantify conformational changes of the proteins. The pattern recognition (PARC) technique was integrated with ILE-based sensor to perform data analysis and provided an effective method to improve the prediction of protein structural changes. The ILE-based stress sensor showed potential of leveraging the amperometric technique to manifest activity of proteins based on various external conditions.