Chiral-Induced Spin Selectivity Modulated Time-Correlated Single-Photon Counting for DNA Hybridization Detection.

The chiral-induced spin selectivity (CISS) effect can distinguish between the spin of electrons as they pass through chiral molecules by backscattering one of the spin components. Herein, we explore the role of the CISS effect in time-correlated single-photon counting measurements to detect DNA hybridization. We observe that the average lifetime of optical excited states of quantum dots attached to double-stranded DNA (dsDNA) varies with directions of the applied magnetic field. Specifically, the difference in the nonradiative average decay lifetime for the two orientations of the applied magnetic field is 2.21 ns in the case of hybridized strands, which is 130 times higher than that observed with quantum dots attached to single-strand DNA. Additionally, we investigate the application of Fourier transform infrared (FTIR) spectroscopy for detecting double-stranded DNA in the presence of a magnetic field, establishing a theoretical framework to substantiate the experimental evidence of magnetic field-dependent FTIR spectroscopy for dsDNA.

Sequence-controlled chiral induced spin selectivity effect in ds-DNA.

In this research, we explore sequence-dependent chiral-induced spin selectivity (CISS) in double-stranded (ds)-DNA using time-correlated single-photon counting and electrochemical impedance spectroscopy supplemented by tight-binding calculations of the phenomenon for the first time. The average lifetime of the photo-excited electrons in a Quantum Dot-DNA system is influenced by the CISS effect generated by the DNA molecule, and the difference in average time decay of electrons was found to be 345 ps for opposite polarity ("UP" and "DOWN") of spins due to the CISS effect. Moreover, the yield of spin-polarized electrons due to the CISS effect was reduced by more than 35% from perfect DNA to DNA with point mutations. Remarkably, by employing a tight binding method combined with Green's function formalism for transport, simulations of the process support the observed experimental trends. Our results provide a basic understanding of the sequence-specific spin-dependent electron transfer through ds-DNA. These results would help to build spin-based next-generation DNA sensors.

Spin-phonon coupling in a double-stranded model of DNA.

We address the electron-spin-phonon coupling in an effective model Hamiltonian for DNA to assess its role in spin transfer involved in the Chiral-Induced Spin Selectivity (CISS) effect. The envelope function approach is used to describe semiclassical electron transfer in a tight-binding model of DNA at half filling in the presence of intrinsic spin-orbit coupling. Spin-phonon coupling arises from the orbital-configuration dependence of the spin-orbit interaction. We find spin-phonon coupling only for the acoustic modes, while the optical modes exhibit electron-phonon interaction without coupling to spin. We derive an effective Hamiltonian whose eigenstates carry spin currents that are protected by spin-inactive stretching optical modes. As optical phonons interact more strongly than acoustic phonons, side buckling and tilting optical base modes will be more strongly associated with decoherence, which allows for the two terminal spin filtering effects found in CISS.

Bone mesh fixation for the treatment of suprailiac hernia. Report of two cases.

Hernias of the lateral abdominal wall are a rare entity. In most cases, they occur after surgery or trauma. We present two cases of lumbar hernia: the first one after iliac bone grafting and the second one after muscular tearing by the seatbelt during a car accident. Both cases were successfully repaired using a propylene mesh with bone fixation.

Las eventraciones de la pared lateral del abdomen son poco frecuentes. Pueden ser posquirúrgicas o causadas por agentes traumáticos. Se presentan dos casos de eventración lumbar: el primero tras una resección ósea por autoinjerto de cresta ilíaca y el segundo por desinserción muscular por cinturón de seguridad secundaria a un accidente en la vía pública. Ambos fueron resueltos quirúrgicamente con colocación de una malla de polipropileno fijada a hueso.

Coherence preservation and electron-phonon interaction in electron transfer in DNA.

We analyze the influence of electron-phonon (e-ph) interaction in a model for electron transfer (ET) processes in DNA in terms of the envelope function approach for spinless electrons. We are specifically concerned with the effect of e-ph interaction on the coherence of the ET process and how to model the interaction of DNA with phonon reservoirs of biological relevance. We assume that the electron bearing orbitals are half filled and derive the physics of e-ph coupling in the vicinity in reciprocal space. We find that at half filling, the acoustical modes are decoupled to ET at first order, while optical modes are predominant. The latter are associated with inter-strand vibrational modes in consistency with previous studies involving polaron models of ET. Coupling to acoustic modes depends on electron doping of DNA, while optical modes are always coupled within our model. Our results yield e-ph coupling consistent with estimates in the literature, and we conclude that large polarons are the main result of such e-ph interactions. This scenario will have strong consequences on decoherence of ET under physiological conditions due to relative isolation from thermal equilibration of the ET mechanism.