Photothermal inactivation of universal viral particles by localized surface plasmon resonance mediated heating filter membrane

Abstract

This study introduces localized surface plasmon resonance (L-SPR) mediated heating filter membrane (HFM) for inactivating universal viral particles by using the photothermal effect of plasmonic metal nanoparticles (NPs). Plasmonic metal NPs were coated onto filter membrane via a conventional spray-coating method. The surface temperature of the HFM could be controlled to approximately 40-60 °C at room temperature, owing to the photothermal effect of the gold (Au) NPs coated on them, under irradiation by visible light-emitting diodes. Due to the photothermal effect of the HFMs, the virus titer of H1Npdm09 was reduced by > 99.9%, the full inactivation time being < 10 min, confirming the 50% tissue culture infective dose (TCID₅₀) assay. Crystal violet staining showed that the infectious samples with photothermal inactivation lost their infectivity against Mardin-Darby Canine Kidney cells. Moreover, photothermal inactivation could also be applied to reduce the infectivity of SARS-CoV-2, showing reduction rate of 99%. We used quantitative reverse transcription polymerase chain reaction (qRT-PCR) techniques to confirm the existence of viral genes on the surface of the HFM. The results of the TCID₅₀ assay, crystal violet staining method, and qRT-PCR showed that the effective and immediate reduction in viral infectivity possibly originated from the denaturation or deformation of membrane proteins and components. This study provides a new, simple, and effective method to inactivate viral infectivity, leading to its potential application in various fields of indoor air quality control and medical science.

Figure 1

Simulation of the photothermal effect generated by Au NPs on a PET microfiber supporting layer. (a) Configuration of Au NPs arrays on the PET microfiber and LED light irradiation. The inset shows a side view of the Au NPs array. (b, c) Top view and side view of temperature distribution by the photothermal effect of 3 × 3 Au NPs array under an optical power density of 100 mW/cm². (d) Variation of surface temperature with respect to the size of Au NPs arrays under different optical power densities. (e) Simplified estimation for surface temperature versus particle numbers per cm² under an optical power density of 100 mW/cm².

Figure 2

Characterization of the as-fabricated HFM. (a) Particle size, UV–Vis absorbance, and SEM image of the synthesized Au NPs. (b) XRD patterns of the PET microfiber with and without Au NPs. (c) Optical image of the HFM. (d, e) SEM and TEM image of the HFM coated with Au NPs. (f) TEM-EDS image of Au NPs on the PET microfiber.

Figure 3

Evaluations of the photothermal effect of HFM. (a) Measurement set-up of the photothermal effect of the HFM under visible light irradiation (530 nm and 560 nm LED light sources). (b, c) TIC images and temperature profiles of the HFM under 530 nm and 560 nm LED light irradiation at an optical power density of 100 mW/cm², respectively, at room temperature. The scale bar is 5 mm. (d) The measured surface temperature changes of HFM and PFM with respect to the wavelength of incident light, the wavelengths of incident light (530 nm and 560 nm). (e) The measured surface temperature of the HFM with respect to an incident optical power density of 560 nm LED irradiation at RT. For the PFM, the surface temperature was measured at an optical power density of 120 mW/cm². (f) Repeatable heating plots of the HFM under 560 nm LED irradiation at an optical power density of 100 mW/cm² at room temperature. (g) Comparative plots of measured and simulated surface temperatures with respect to the optical power density of the incident light and the volume of Au NPs coated on the HFM.

Figure 4

Assessment of the titer of the H1N1pdm09 virus with respect to the PTI time. (a) Schematic view of the PTI kit. (b) Result of the TCID₅₀ assay with respect to the PTI time and natural inactivation. (c) Photographs of the crystal violet staining of the MDCK cells with respect to the PTI time.

Figure 5

Test for photothermal inactivation of the SARS-CoV-2 virus using the s-HFM. (a) Surface temperature of the s-HFM under visible light illumination (100 mW/cm²), (b) Result of the TCID₅₀ assay, and (c) Photograph of the crystal violet staining of the MDCK cells with and without PTI.

Figure 6

Assessment of the titer of the H1N1pdm09 virus with respect to the viral doses (or concentrations) and inactivation times. (a) Results of the TCID₅₀ assay, and (b) Photographs of the crystal violet staining of the MDCK cells with respect to the dose of the virus stock, the exposure time of PTI.

Figure 7

Comparison of the cyclic threshold (Ct) values of each infectious sample for detecting the M-gene of the H1N1 pdm09 virus.

Figure 8

Suggested photothermal inactivation mechanism of the pandemic H1N1pdm09 virus.