A novel method for the study of fluorescent probes in biological material during exposure to microwave radiation.

Abstract

Instrumentation has been developed which allows the monitoring of fluorescence in erythrocyte ghost membranes before, during, and after exposure to microwave radiation. Using non-fluorescent, UV-transmitting fiber optic cables, excitation light of specific wavelengths was delivered to a stirred sample undergoing irradiation (2450 MHz, CW) within a fluid-filled, temperature-controlled waveguide. Fluorescence was collected using an identical cable and transferred through appropriate filters to standard detecting, amplification and recording devices. We have used the fluorescent probe, 1-anilino-8-naphthalene sulfonate (ANS) to monitor the effect of microwave radiation on the binding of calcium to erythrocyte ghosts. Microwave radiation at specific absorption rates of 10 and 200 mW/g had no effect on the binding of ANS to the membranes. Dose-response curves also showed no influence of microwaves on calcium binding between 2.0 and 10.0 x 10(-4) M. In addition, experiments studying fluorescence energy transfer between intrinsic tryptophan residues and membrane bound ANS showed that intermolecular distances between donor and acceptor are also unaffected by microwave radiation. We have thus shown that 2450 MHz microwave radiation at the specific absorption rates used does not interfere with the binding of calcium to erythrocyte ghosts or alter intermolecular distances between intrinsic molecules and bound ANS.

AI evidence extraction

Main findings

Instrumentation was developed to monitor fluorescence in erythrocyte ghost membranes before/during/after 2450 MHz continuous-wave microwave exposure in a temperature-controlled waveguide. At reported specific absorption rates of 10 and 200 mW/g, microwave exposure had no effect on ANS binding to membranes, did not influence calcium binding across tested concentrations, and did not affect fluorescence energy transfer-derived intermolecular distances.

Outcomes measured

• ANS fluorescence binding to erythrocyte ghost membranes
• Calcium binding to erythrocyte ghosts (dose-response 2.0 to 10.0 x 10(-4) M)
• Fluorescence energy transfer (tryptophan to membrane-bound ANS) / inferred intermolecular distances

Limitations

• Sample size not reported in abstract
• Exposure duration not reported in abstract
• Biological material is an in vitro membrane preparation (erythrocyte ghosts), limiting generalizability to whole organisms
• Temperature control is mentioned but quantitative thermal measurements/controls are not detailed in the abstract

{
    "study_type": "engineering",
    "exposure": {
        "band": "microwave",
        "source": null,
        "frequency_mhz": 2450,
        "sar_wkg": null,
        "duration": null
    },
    "population": null,
    "sample_size": null,
    "outcomes": [
        "ANS fluorescence binding to erythrocyte ghost membranes",
        "Calcium binding to erythrocyte ghosts (dose-response 2.0 to 10.0 x 10(-4) M)",
        "Fluorescence energy transfer (tryptophan to membrane-bound ANS) / inferred intermolecular distances"
    ],
    "main_findings": "Instrumentation was developed to monitor fluorescence in erythrocyte ghost membranes before/during/after 2450 MHz continuous-wave microwave exposure in a temperature-controlled waveguide. At reported specific absorption rates of 10 and 200 mW/g, microwave exposure had no effect on ANS binding to membranes, did not influence calcium binding across tested concentrations, and did not affect fluorescence energy transfer-derived intermolecular distances.",
    "effect_direction": "no_effect",
    "limitations": [
        "Sample size not reported in abstract",
        "Exposure duration not reported in abstract",
        "Biological material is an in vitro membrane preparation (erythrocyte ghosts), limiting generalizability to whole organisms",
        "Temperature control is mentioned but quantitative thermal measurements/controls are not detailed in the abstract"
    ],
    "evidence_strength": "low",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "microwave radiation",
        "2450 MHz",
        "continuous wave",
        "fluorescence monitoring",
        "fiber optic cables",
        "erythrocyte ghost membranes",
        "ANS",
        "calcium binding",
        "fluorescence energy transfer",
        "specific absorption rate"
    ],
    "suggested_hubs": []
}

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