Electrochemical aptasensor based on anisotropically modified (Janus-type) gold nanoparticles for determination of C-reactive protein

Review of Advances in Coating and Functionalization of Gold Nanoparticles: From Theory to Biomedical Application

Nanoparticles, especially gold nanoparticles (Au NPs) have gained increasing interest in biomedical applications. Used for disease prevention, diagnosis and therapies, its significant advantages in therapeutic efficacy and safety have been the main target of interest. Its application in immune system prevention, stability in physiological environments and cell membranes, low toxicity and optimal bioperformances are critical to the success of engineered nanomaterials. Its unique optical properties are great attractors. Recently, several physical and chemical methods for coating these NPs have been widely used. Biomolecules such as DNA, RNA, peptides, antibodies, proteins, carbohydrates and biopolymers, among others, have been widely used in coatings of Au NPs for various biomedical applications, thus increasing their biocompatibility while maintaining their biological functions. This review mainly presents a general and representative view of the different types of coatings and Au NP functionalization using various biomolecules, strategies and functionalization mechanisms.

The Fabrication of a Probe-Integrated Electrochemiluminescence Aptasensor Based on Double-Layered Nanochannel Array with Opposite Charges for the Sensitive Determination of C-Reactive Protein

The effective and sensitive detection of the important biomarker, C-reactive protein (CRP), is of great significance in clinical diagnosis. The development of a convenient and highly sensitive electrochemiluminescence (ECL) aptasensor with an immobilized emitter probe is highly desirable. In this work, a probe-integrated ECL aptamer sensor was constructed based on a bipolar silica nanochannel film (bp-SNF) modified electrode for the highly sensitive ECL detection of CRP. The bp-SNF, modified on an ITO electrode, consisted of a dual-layered SNF film, including the negatively charged inner SNF (n-SNF) and the outer SNF with a positive charge and amino groups (p-SNF). The ECL emitter, tris(bipyridine) ruthenium (II) (Ru(bpy)32+), was stably immobilized in a nanochannel of bp-SNF using the dual electrostatic interactions with n-SNF attracting and p-SNF repelling. The amino groups on the outer surface of bp-SNF were aldehyde derivatized, allowing for the covalent immobilization of recognitive aptamers (5'-NH2-CGAAGGGGATTCGAGGGGTGATTGCGTGCTCCATTTGGTG-3'), leading to the recognition interface. When CRP bound to the aptamer on the recognition interface, the formed complex increased the interface resistance and reduced the diffusion of the co-reactant tripropylamine (TPA) into the nanochannels, leading to a decrease in the ECL signal. Based on this mechanism, the constructed aptamer sensor could achieve a sensitive ECL detection of CRP ranging from 0.01 to 1000 ng/mL, with a detection limit (DL) of 8.5 pg/mL. The method for constructing this probe-integrated ECL aptamer sensor is simple, and it offers a high probe stability, good selectivity, and high sensitivity.

PEG-functionalized black phosphorus quantum dots as stable and biocompatible electrochemiluminescence luminophores for sensitive detection of tumor biomarker

Despite black phosphorous (BP) QDs possess the merits of size-tunable band-gap, high electron mobility, and intrinsic defects, the spontaneous agglomeration and rapid oxidation of BP QDs in aqueous solution caused low electrochemiluminescence (ECL) efficiency and unstable ECL signal, which confined its further application of biological analysis. Herein, polyethylene glycol-functionalized BP QDs (PEG@BP QDs) were prepared showing an efficient and stable ECL response, which is attributed to the fact that PEG as protectant not only effectively prevented the spontaneous agglomeration, but also restrained the rapid oxidation of BP QDs in aqueous solution. As proof-of-concept, PEG@BP QDs were used as an efficient ECL emitter to combine with palindrome amplification-induced DNA walker to construct a sensitive ECL aptasensing platform for detecting cancer marker mucin 1 (MUC1). Interestingly, with the aid of positively charged thiolated PEG, the reaction rate of DNA walker on the electrode interface was clearly increased for the recovery of the ECL signal. The ECL aptasensor provides sensitive determination with the detection limit of 16.5 fg/mL. The proposed strategy paves a path for the development of efficient and stable ECL nanomaterials to construct biosensors for biosensing and clinical diagnosis.

Application of Janus Particles in Point-of-Care Testing

Janus particles (JPs), named after the two-faced Roman god, are asymmetric particles with different chemical properties or polarities. JPs have been widely used in the biomedical field in recent years, including as drug carriers for targeted controlled drug release and as biosensors for biological imaging and biomarker detection, which is crucial in the early detection and treatment of diseases. In this review, we highlight the most recent advancements made with regard to Janus particles in point-of-care testing (POCT). Firstly, we introduce several commonly used methods for preparing Janus particles. Secondly, we present biomarker detection using JPs based on various detection methods to achieve the goal of POCT. Finally, we discuss the challenges and opportunities for developing Janus particles in POCT. This review will facilitate the development of POCT biosensing devices based on the unique properties of Janus particles.