Driving DNA Origami Assembly with a Terahertz Wave.

Terahertz (THz) waves show nontrivial interactions with living systems, but the underlying molecular mechanisms have yet to be explored. Here, we employ DNA origami as a model system to study the interactions between THz waves and DNA structures. We find that a 3-min THz illumination (35.2 THz) can drive the unwinding of DNA duplexes at ∼10 °C below their melting point. Computational study reveals that the THz wave can resonate with the vibration of DNA bases, provoking the hydrogen bond breaking. The cooperation of thermal and nonthermal effects allows the unfolding of undesired secondary structures and the THz illumination can generate diverse DNA origami assemblies with the yield (>80%) ∼ 4-fold higher than that by the contact heating at similar temperatures. We also demonstrate the in situ assembly of DNA origami in cell lysate. This method enables remotely controllable assembly of intact biomacromolecules, providing new insight into the bioeffects of THz waves.

Effects of electromagnetic waves on pathogenic viruses and relevant mechanisms: a review.

Pathogenic viral infections have become a serious public health issue worldwide. Viruses can infect all cell-based organisms and cause varying injuries and damage, resulting in diseases or even death. With the prevalence of highly pathogenic viruses, such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), it is urgent to develop efficient and safe approaches to inactivate pathogenic viruses. Traditional methods of inactivating pathogenic viruses are practical but have several limitations. Electromagnetic waves, with high penetration capacity, physical resonance, and non-contamination, have emerged as a potential strategy to inactivate pathogenic viruses and have attracted increasing attention. This paper reviews the recent literature on the effects of electromagnetic waves on pathogenic viruses and their mechanisms, as well as promising applications of electromagnetic waves to inactivate pathogenic viruses, to provide new ideas and methods for this inactivation.

Nonthermal Ultrafast Optical Control of Magnetization Dynamics by Linearly Polarized Light in Metallic Ferromagnet.

Coherent optical control of the magnetization in ferromagnetic (FM) mediums using ultrafast nonthermal effect paves a promising avenue to improve the speed and repetition rate of the magnetization manipulation. Whereas previously, only heat-induced or helicity-dependent magnetization dynamics are demonstrated in metallic ferromagnets. Here, the linearly-polarized light control of magnetization is demonstrated in FM Co coupled with ferroelectric (FE) BiFeO3 by tuning the light polarization direction. It is revealed that in the Co/BiFeO3 heterostructure excited by femtosecond laser pulses, the magnetization precession amplitude follows a sinusoidal dependence on the laser polarization direction. This nonthermal control of coherent magnetization rotation is attributed to the optical rectification effect in the BiFeO3 layer, which yields a FE polarization depending on the light polarization, and the subsequent modulation of magnetic energy in Co by the electrostriction-induced strain. This work demonstrates an effective route to nonthermally manipulate the ultrafast magnetization dynamics in metallic ferromagnets.

THz-PCR Based on Resonant Coupling between Middle Infrared and DNA Carbonyl Vibrations.

The carbonyl groups of deoxyribonucleotide can resonantly couple with 53 THz middle infrared, which can highly transmit water without ionization-based damage to DNA molecules. Herein, we predict that vibrational coupling with THz irradiation could lower down the hybridization landscape of nucleic acids and thus affect DNA replication. Using polymerase chain reaction (PCR) as a measure, we found that THz shining can reduce the denature temperature of DNA duplexes by about 3 °C, which allows one to conduct PCR at lower temperature, facilitating long-time amplification reaction without losing enzymatic fidelity, i.e., normal PCR should be carried out at denaturing temperature ∼4 °C higher than the melting temperature (Tm), but THz-PCR only requires temperature ∼1 °C higher than Tm due to the nonthermal effect of THz shining. Moreover, the melting time can also be shortened to 1/5 due to the enhanced vibration coupling with 53 THz irradiation. We proposed THz-PCR as an innovated DNA amplification technique with ultrahigh specificity and sensitivity and also successfully demonstrated its advantages in forensic detections.

A Two-Step Microwave Annealing Process for PAN Pre-Oxidation through a TM-Mode Cavity.

A novel microwave annealing system and a specific processing condition are proposed for the pre-oxidation of carbon fiber. The microwave annealing system consists of a TM-mode resonant cavity and a silicon carbide (SiC) susceptor. The TM-mode cavity enhances the electric field at the center. The SiC susceptor absorbs part of the microwave energy and converts it to heat. The enhanced fields and the SiC susceptor provide both nonthermal and thermal treatments for fibrous materials with various dielectric properties. Furthermore, a two-step microwave annealing process is used to oxidize polyacrylonitrile (PAN) fiber. The scanning electron microscopy (SEM) images, differential scanning calorimetry (DSC), and X-ray diffraction (XRD) results support the theory that the microwave annealing can achieve a high aromatic index of 66.39% in just 13 min, 9 times faster than the traditional processing time. The results of the Raman spectra also illustrate that the sheath-core factor of the microwave-heated specimen is closer to one than that of the conventional furnace-heated type, which agree with the images of the cross-section area.

Effects of Ohmic Heating, Including Electric Field Intensity and Frequency, on Thermal Inactivation of Bacillus subtilis Spores.

Methods for microbial inactivation are important in the food industry; however, conventional external heating (CH) reduces food quality. Accordingly, the nonthermal effects of ohmic heating (OH) on Bacillus subtilis spores in a sodium chloride aqueous solution at 101°C (i.e., the boiling point), as well as the effects of electric field intensity and frequency during OH, were investigated. Survival kinetics were compared between OH and external CH. The inactivation effect on B. subtilis was greater for all electric field conditions (5, 10, and 20 V/cm) than for CH. In particular, 20 V/cm showed a significantly higher inactivation effect (P < 0.05) on B. subtilis than those of CH at 8, 10, 12, 14, and 16 min. The survival data were fitted to various primary kinetic models. In the Weibull model and the log-linear model, there were significant differences (P < 0.05) in the rate parameters δ and kmax between OH at 20 V/cm and CH. However, there were no significant differences (P > 0.05) in survival kinetics between 20, 40, and 60 kHz; B. subtilis spores were inactivated more efficiently as the frequency increased. B. subtilis spores were almost completely inactivated at 14 to 16 min for the 60-kHz treatment, but spores were still alive at 20 and 40 kHz for the same treatment times. These results demonstrated that OH inactivates B. subtilis spores more effectively than CH. OH conditions with high electric field intensities and high frequencies resulted in efficient B. subtilis spore inactivation.

Multisynergistic Platform for Tumor Therapy by Mild Microwave Irradiation-Activated Chemotherapy and Enhanced Ablation.

Microwave (MW) therapy, as a promising type of thermal therapy, has been attracting more and more attention from scientists. The combination of thermal and chemotherapy is of great significance in the latest studies of synergistic tumor therapy. However, the research on the MW therapy mechanism, especially the nonthermal effect applied in the combined cancer therapy, is not thorough enough. Pleasantly, we have discovered that nonthermal MW irradiation can promote the cellular uptake of nanoparticles and anticancer drugs via experiments in vitro and in vivo. Therefore, multifunctional nanoplatforms have been designed for enhanced tumor inhibition by loading ionic liquids (ILs), doxorubicin hydrochloride (DOX), and phase change materials (PCMs) into ZrO2 hollow nanoparticles. PCMs act as MW switches. The as-made IL-DOX-PCM@ZrO2 nanoplatforms were injected into H22-tumor-bearing mice via the tail vein. Mild microwave irradiation (0.9 W, 450 MHz) was then applied. The thermal effect of MW could cause the temperature of the tumor site to rise (58 °C). On the other hand, it will trigger the MW switch to open and release DOX when the temperature is high enough. At the same time as drug release, a MW nonthermal effect could improve the cellular uptake of nanomaterials and anticancer drugs. The multisynergistic effect can promote the survival rate of the IL-DOX-PCM@ZrO2+MW group to 100%. The results of the tumor therapy experiment in vivo demonstrated that as-made multifunctional IL-DOX-PCM@ZrO2 nanoplatforms could enhance the therapeutic outcome of combined thermal and chemotherapy under mild MW irradiation.