Electrochemistry for Atom Transfer Radical Polymerization

Electrochemical biosensor for highly sensitive detection of cTnI based on a dual signal amplification strategy of ARGET ATRP and ROP

Cardiac troponin I (cTnI), a gold biomarker for the diagnosis of acute myocardial infarction (AMI), plays a vital role in the early diagnosis, treatment and prognosis analysis of AMI. In this paper, an electrochemical biosensor for the highly sensitive determination of cTnI was fabricated based on the dual signal amplification strategy of electron transfer atom transfer radical polymerization (ARGET ATRP) and ring-opening polymerization (ROP) for the first time. Briefly, the thiolate cTnI-aptamer 1, which was bonded to the electrode via Au-S bonds, specifically captured cTnI to the electrode surface. Then, cTnI-aptamer 2 (Apt2) was successfully introduced to the electrode surface to form Apt-cTnI-Apt sandwich structure. Subsequently, the initiator BIBB was connected to Apt2 through bromination reaction, and then the resulting ATRP polymer was employed as a macromolecular initiator for the succeeding reaction. Next, the monomers, α-amino acid-N-carboxylic acid anhydride ferrocene derivatives (NCA-Fc), used for the ROP reaction produced numerous electroactive polymers on the electrode surface. The dual action of ARGET ATRP and ROP significantly improved sensitivity of cTnI biosensor assay, the prepared biosensor displayed a wide linear detection range from 100 fg mL-1 to 100 ng mL-1, with a detection limit of 32.24 fg mL-1. The method exhibited favorable selectivity, simple operation and excellent stability. Furthermore, the biosensor still rendered satisfactory analytical performance in the detection of clinical serum samples, indicating the application potential in clinical diagnosis.

Solvent Coordination Effect on Copper-Based Molecular Catalysts for Controlled Radical Polymerization

The equilibrium of copper-catalyzed atom transfer radical polymerization was investigated in silico with the aim of finding an explanation for the experimentally observed solvent effect. Various combinations of alkyl halide initiators and copper complexes in acetonitrile (MeCN) and dimethyl sulfoxide (DMSO) were taken into consideration. A continuum model for solvation, which does not account for the explicit interactions between the solvent and metal complex, is not adequate and does not allow the reproduction of the experimental trend. However, when the solvent molecules are included in the coordination sphere of the copper(I,II) species and the continuum description of the medium is still used, a solvent dependence of process thermodynamics emerges, in fair agreement with experimental trends.

Atom Transfer Radical Polymerization: A Mechanistic Perspective

Since its inception, atom transfer radical polymerization (ATRP) has seen continuous evolution in terms of the design of the catalyst and reaction conditions; today, it is one of the most useful techniques to prepare well-defined polymers as well as one of the most notable examples of catalysis in polymer chemistry. This Perspective highlights fundamental advances in the design of ATRP reactions and catalysts, focusing on the crucial role that mechanistic studies play in understanding, rationalizing, and predicting polymerization outcomes. A critical summary of traditional ATRP systems is provided first; we then focus on the most recent developments to improve catalyst selectivity, control polymerizations via external stimuli, and employ new photochemical or dual catalytic systems with an outlook to future research directions and open challenges.