Entropy-driven strand displacement reaction for ultrasensitive detection of circulating tumor DNA based on upconversion and Fe_(3)O_(4) nanocrystals

Early detection of cancer biomarkers applied in real-time disease diagnosis and therapies can increase the survival rate of patients.Circulating tumor DNA(ct DNA)as a typical cancer biomarker plays a great role in the process of tumor disease monitoring,especially in early diagnosis.Unfortunately,most ct DNA detection systems have not been widely used due to their low sensitivity,poor specificity,and high cost.Herein,we developed an alternative ct DNA detection system to present the levels of ct DNA by recording the fluorescence signals of the system containing upconversion nanoparticles(UCNPs),Fe_(3)O_(4),and entropy-driven strand displacement reaction.The method has a practical sensitivity with a wide linear range from 100 amol L^(-1)to 1 nmol L^(-1)and a low detection limit of 1.6 amol L^(-1).Furthermore,the system demonstrates a practical application in mouse blood serum samples and meets the requirements for rapid,sensitive,specific,and economical diagnosis of cancers.Thus,this ct DNA detection system may have great potential for ct DNAdetection and clinical diagnosis.

Entropy-driven self-assembly of tethered Janus nanoparticles on a sphere

Understanding the effect of curvature and topological frustration on self-assembly yields insight into the mechanistic details of the ordering of identical subunits in curved spaces,such as the assembly of viral capsids,growth of solid domains on vesicles,and the self-assembly of molecular monolayers.However,the self-assembly of nanoparticles with anisotropic surface topology and compartmentalization on curved surfaces remains elusive.By combining large-scale molecular simulations as well as theoretical analysis,we demonstrate here that the interplay among anisotropy,curvature,and chain conformation induces tethered Janus nanoparticles to self-assemble into diverse novel structures on a sphere,including binary nanocluster(C_(B)),trinary nanocluster(C_(T)),nanoribbon(R_(N))and hexagon with centered reverse(HR),which are mapped on a phase diagram related to the length asymmetry of tethered chains and Janus balance of the nanoparticles.The dynamical mechanism for the formation of these structure states is analyzed by examining the detailed kinetic pathways as well as free energy.We also show that the centered-reverse state is more prone to emerging around the topological defects,indicating the defect-enhanced entropy effect on a curved surface.Finally,the analytical model that rationalizes the regimes of these structure states is developed and fits simulations reasonably well,resulting in a mechanistic interpretation based on the order through entropy.Our findings shed light on curvature engineering as a versatile strategy to tailor the superstructures formed by anisotropic building blocks toward unique properties.