Separation and preconcentration of riboflavin from human plasma using polythionine coated magnetite/hydroxyapatite nanocomposite prior to analysis by surfactant-enhanced fluorimetry

Conductive Polymer-Based Nanocomposites as Powerful Sorbents: Design, Preparation and Extraction Applications

Conductive polymers as composite materials have been attracted tremendous attention due to their versatile and excellent features such as tunable conductivity, facile synthesis and fabrication, high chemical and thermal stability etc. These characteristics make them versatile and let them being used in numerous fields including microelectronics, optics and biosensors. Throughout the mentioned fields, conductive polymers particularly perform as effective sorbents. Although tremendous efforts have been put into this topic, to the best of our knowledge, a comprehensive up-to-date review on the applications of conductive polymers as efficient sorbents has not been reported. The main objective of this paper is to make a significant contribution to the recent literature toward the synthesis and extraction applications of conductive polymers as efficient sorbents.

Application of magnetic nanomaterials in bioanalysis

The importance of magnetic nanomaterials and magnetic hybrid materials, which are classified as new generation materials, in analytical applications is increasingly understood, and research on the adaptation of these materials to analytical methods has gained momentum. Development of sample preparation techniques and sensor systems using magnetic nanomaterials for the analysis of inorganic, organic and biomolecules in biological samples, which are among the samples that analytical chemists work on most, are among the priority issues. Therefore in this review, we focused on the use of magnetic nanomaterials for the bioanalytical applications including inorganic and organic species and biomolecules in different biological samples such as primarily blood, serum, plasma, tissue extracts, urine and milk. We summarized recent progresses, prevailing techniques, applied formats, and future trends in sample preparation-analysis methods and sensors based on magnetic nanomaterials (Mag-NMs). First, we provided a brief introduction of magnetic nanomaterials, especially their magnetic properties that can be utilized for bioanalytical applications. Second, we discussed the synthesis of these Mag-NMs. Third, we reviewed recent advances in bioanalytical applications of the Mag-NMs in different formats. Finally, recently literature studies on the relevance of Mag-NMs for bioanalysis applications were presented.

Greenness of magnetic nanomaterials in miniaturized extraction techniques: A review

Green analytical chemistry principles should be followed, as much as possible, and particularly during the development of analytical sample preparation methods. In the past few years, outstanding materials such as ionic liquids, metal-organic frameworks, carbonaceous materials, molecularly imprinted materials, and many others, have been introduced in a wide variety of miniaturized techniques in order to reduce the amount of solvents and sorbents required during the analytical sample preparation step while pursuing more efficient extraction methods. Among them, magnetic nanomaterials (MNMs) have gained special attention due to their versatile properties. Mainly, their ability to be separated from the sample matrix using an external magnetic field (thus enormously simplifying the entire process) and their easy combination with other materials, which implies the inclusion of a countless number of different functionalities, highly specific in some cases. Therefore, MNMs can be used as sorbents or as magnetic support for other materials which do not have magnetic properties, the latter permiting their combination with novel materials. The greenness of these magnetic sorbents in miniaturized extractions techniques is generally demonstrated in terms of their ease of separation and amount of sorbent required, while the nature of the material itself is left unnoticed. However, the synthesis of MNMs is not always as green as their applications, and the resulting MNMs are not always as safe as desired. Is the analytical sample preparation field ready for using green magnetic nanomaterials? This review offers an overview, from a green analytical chemistry perspective, of the current state of the use of MNMs as sorbents in microextraction strategies, their preparation, and the analytical performance offered, together with a critical discussion on where efforts should go.

Signalling probe displacement electrochemical aptasensor for malignant cell surface nucleolin as a breast cancer biomarker based on gold nanoparticle decorated hydroxyapatite nanorods and silver nanoparticle labels

Nucleolin is a multifunctional protein that is markedly overexpressed on the surface of most cancer cells. By taking advantage of the high affinity and specificity of the AS1411 aptamer for nucleolin, a signalling probe displacement electrochemical aptasensor was developed. The thiolated AS1411 aptamer was conjugated to hydroxyapatite nanorods (HApNRs) decorated with gold nanoparticles (AuNPs). To further increase the electrical conductivity of the interface, the ionic liquid 1-ethyl-3-methylimidazolium alanine with its high ion conductivity was placed on the electrode surface. Then, the aptamer was immobilized on the modified electrode and conjugated to signalling c-DNA tagged with AgNPs (c-DNA@AgNPs). In the presence of the MCF7 target cells, the signalling probe is displaced and released from the electrode surface. This leads to a decrease in the current that is proportional to the concentration of cancer cells in the range from 10 to 106 cells mL-1, with a detection limit as low as 8 ± 2 cells mL-1 (n = 3) (based as 3σ/m, where σ is the standard deviation of the blank and m is the slope of the calibration plot). This method presents a promising tool for highly sensitive and selective detection of surface nucleolin on MCF7 cancer cells. Graphical abstract HApNR-AuNP-AS1411 aptamer nanocomposite as an electrochemical sensing interface was immobilized on the gold electrode surface and conjugated to signaling c-DNA tagged with AgNPs for determination of surface nucleolin on MCF7 cancer cells.

A review: Aptamer-based analytical strategies using the nanomaterials for environmental and human monitoring of toxic heavy metals

Recent developments in biotechnology offer the new methods for the sensitive detection of heavy metals based on the affinity and specificity of aptamers, as nucleic acid ligands selected from random sequence pools in vitro. Heavy metals have received considerable importance as the most toxic metallic pollutants which may cause serious environmental damages. They are classified as trace elements because of their presence in trace concentrations in various environmental matrices. Thus, the precise and sensitive methods to detect heavy metals are important to ensure human and environment safety. Aptamers as the biological probes, show high binding affinity which can often be directly translated into high detection sensitivity. On the other hand, high selectivity and stability make them possible to detect a wide range of targets, especially metallic ions. This review provides current progress of aptamers for environmental and biological monitoring of heavy metals using the nanomaterials mainly in two groups: (i) aptamer based biosensors (aptasensors) and (ii) aptamer based biosorbents (aptasorbents). The introduction of nanomaterials can efficiently increase the immobilization quantity of aptamers. Furthermore, they play an important role in the orientation and assembly density controlling of aptamers for the optimized recognition ability.