In vitro investigation of the biological effects associated with human dermal fibroblasts exposed to 2.52 THz radiation

711th Human Performance Wing, Radio Frequency Radiation Branch, Air Force Research Laboratory, Brooks City-Base, Texas, USA.
Lasers in Surgery and Medicine (Impact Factor: 2.62). 02/2011; 43(2):152-63. DOI: 10.1002/lsm.20960
Source: PubMed

ABSTRACT Terahertz (THz) radiation sources are increasingly being used in military, defense, and medical applications. However, the biological effects associated with this type of radiation are not well characterized. In this study, we evaluated the cellular and molecular response of human dermal fibroblasts exposed to THz radiation.
In vitro exposures were performed in a temperature-controlled chamber using a molecular gas THz laser (2.52 THz, 84.8 mW cm(-2), durations: 5, 10, 20, 40, or 80 minutes). Both computational and empirical dosimetric techniques were conducted using finite-difference time-domain (FDTD) modeling approaches, infrared cameras, and thermocouples. Cellular viability was assessed using conventional MTT assays. In addition, the transcriptional activation of protein and DNA sensing genes were evaluated using qPCR. Comparable analyses were also conducted for hyperthermic and genotoxic positive controls.
We found that cellular temperatures increased by 3°C during all THz exposures. We also found that for each exposure duration tested, the THz and hyperthermic exposure groups exhibited equivalent levels of cell survival (≥90%) and heat shock protein expression (∼3.5-fold increases). In addition, the expression of DNA sensing and repair genes was unchanged in both groups; however, appreciable increases were observed in the genotoxic controls.
Human dermal fibroblasts exhibit comparable cellular and molecular effects when exposed to THz radiation and hyperthermic stress. These findings suggest that radiation at 2.52 THz generates primarily thermal effects in mammalian cells. Therefore, we conclude that THz-induced bioeffects may be accurately predicted with conventional thermal damage models.

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Available from: Caleb C. Roth, Dec 09, 2014
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    • "Moreover, THz radiation , with its low energy nature, can be safely used in nondestructive investigations of biomolecular peptides [7], proteins [8], and DNA [9]. Recently, terahertz radiation have found application in in vitro investigations of the biomedical effects [10]. The THz band is located in a specific region of the far infrared spectrum (FIRregion ), where heavy molecules exhibit unique spectral fingerprints [11].We can recognize two main methods of the THz generation: continuous waves like BWO tubes (Backward-Wave Oscillators) [12], THz lasers [13], Quantum Cascade Lasers (QCL) [14], THz photomixers [15]; and pulsed THz generators used in the arrangements of time domain spectroscopy (TDS) [16]. "
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    Optical Materials 11/2014; 37. DOI:10.1016/j.optmat.2014.04.032 · 1.98 Impact Factor
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    • "Recent progress in the development of broadband terahertz (THz) pulse sources based on ultrafast lasers1 has led to applications of THz pulses as a non-invasive tool in cancer diagnosis23456, intra-operative tumor margin identification7, assessment of burns8 and in vivo skin9 and cornea10 hydration sensing. At the same time, we are only starting to uncover how THz radiation, and especially intense THz pulses with duration on the order of 1 ps and peak electric fields on the order of 100 kV/cm and higher, interacts with biological tissue111213141516171819. With photon energies typically in the range from 0.5–15 meV, THz radiation is non-ionizing, and the mechanisms by which it interacts with cells and tissues are fundamentally different from those involved in interactions of living matter with high-energy ionizing radiation (i.e., UVB, UVC, X-rays, gamma rays) that cause damage by directly breaking covalent bonds in DNA and other biomolecules. "
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    • "Within the measurement error of the device (± 0.05°C), there was no change in temperature of the skin of C57BL/6J mice that were exposed to fs-pulsed THz radiation (Fig. S2A). To evaluate for the presence of THz radiation-induced thermal or nonspecific stress, we measured expression of heat shock protein 70 (Hsp70)1920 at the mRNA (Fig. S2B) and protein levels1920 (Fig. S2C). Thermal stimulus on NIH-3T3 fibroblasts was check as a positive control with Hsp70 members including Hspa1a, Hspa4l and Hsph1. "
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