In Situ Assembly of Nanomaterials and Molecules for the Signal Enhancement of Electrochemical Biosensors

The physiochemical properties of nanomaterials have a close relationship with their status in solution. As a result of its better simplicity than that of pre-assembled aggregates, the in situ assembly of nanomaterials has been integrated into the design of electrochemical biosensors for the signal output and amplification. In this review, we highlight the significant progress in the in situ assembly of nanomaterials as the nanolabels for enhancing the performances of electrochemical biosensors. The works are discussed based on the difference in the interactions for the assembly of nanomaterials, including DNA hybridization, metal ion–ligand coordination, metal–thiol and boronate ester interactions, aptamer–target binding, electrostatic attraction, and streptavidin (SA)–biotin conjugate. We further expand the range of the assembly units from nanomaterials to small organic molecules and biomolecules, which endow the signal-amplified strategies with more potential applications.

Enabling Tunable Hydrophilicity of PDMS via Metal-ligand Coordinated Dynamic Networks

Polydimethylsiloxane (PDMS) has been widely used in various fields due to its appealing physical and chemical properties. However, its high hydrophobicity not only yields poor adhesion to substrates but also facilitates undesired adsorption of substances such as proteins, biofoulers, etc., which limits the performance and lifetime of PDMS. Moreover, traditional surface modification techniques are often not efficient on PDMS surfaces because of the surface reconstruction. Although new methods involving chemical modification have been developed, most of them require complicated procedures and equipment. To overcome this challenge, we incorporate metal-ligand coordination, a non-covalent interaction bearing polar functionality, into PDMS, which exposes the hydrophilicity progressively upon dynamic bond breakage and reformation. We demonstrate that the hydrophilicity of coordinated PDMS can be tailored by the choice of network structure, counter anions, and metal cations, which yield distinct network dynamics. The wetting mechanism is discussed in the context of chain reconfiguration and surface reconstruction. We also show that a properly designed metal-ligand coordinated PDMS has potential as a superior marine fouling release coating by weakening diatom attachment. Through this paper, we introduce a new concept for tuning material hydrophilicity via dynamic polar functionalities, which is applicable to a wide range of polymers.

DFT Studies and Molecular Dynamics of the Molecular and Electronic Structure of Cu (II) and Zn (II) Complexes with the Symmetric Ligand (Z)-2-((3,5-dimethyl-2H-pyrrol-2-yl) methylene)-3,5-dimethyl-2H-pyrrole

The binding patterns of the metal cations Cu 2+ and Zn 2+ with the symmetric ligands (Z)-2-((3,5-dimethyl-2H-pyrrol-2-yl) methylene)-3,5-dimethyl-2H-pyrrole (L1) and (Z)-2-(1-(3,5-dimethyl-2H-pyrrol-2-yl)ethylidene)-3,5-dimethyl-2H-pyrrole (L2), have been investigated at B3LYP and MM2 level of theories in the gas phase and a solution respectively. Natural bond orbital (NBO) analysis has been applied to explore the character of metal-ligand coordination. The stability of the most favorable binding motifs of the metal ions has also been investigated by the molecular dynamics (MD) simulation. Finally, the inhibition activity of the complexes (L1Cu2+), (L2Cu2+), (L1Zn2+), and (L2Zn2+) against the DNA dependent protein kinase also have been investigated by molecular docking studies.