Optical imaging through scattering media via magnetically modulated fluorescence

Abstract

A weak (< 1000 G) magnetic field can influence photochemical processes through its effect on electron spin dynamics in a photogenerated radical pair. In a solution of pyrene and dimethylaniline this effect manifests as magnetic field-dependent exciplex fluorescence. Here we describe magnetofluorescence imaging (MFI). A localized magnetic null defines a fluorescence detection volume, which is scanned through a sample to create an image. MFI forms an image without lenses and in the presence of arbitrarily strong optical scattering. The resolution of MFI is in principle not limited by optical diffraction, although the present implementation is far from the diffraction limit.

Fluorescent nanodiamonds enable quantitative tracking of human mesenchymal stem cells in miniature pigs

“…No extraction or other laborious separation steps prior to the fluorescence intensity measurement are required. Although magnetic modulation is less common than optical modulation, which has been successfully applied for probing photoswitchable fluorescent proteins36, it is more applicable to samples with strong light scattering and complex chemical compositions37. The method is ideally suitable for selective imaging of FNDs in tissues and also sensitive detection of FNDs in highly contaminated solution.…”

Development of lock-in based overtone modulated MARY spectroscopy for detection of weak magnetic field effects

“…20 There are other, related, techniques which make use of the field-modulation and derivative detection. In recent years, field-modulation technique has been combined with laser scanning to yield both fluorescence 21 and absorptionbased ModMARY imaging 22,23 (referred to as magnetofluorescence imaging (MFI) and magnetic intensity modulation (MIM) imaging respectively). The general technique of stimulus-modulation can be seen in many fields of spectroscopy, most notably optical spectroscopy, for example in frequency (wavelength) modulation using tunable light sources, cavity spectroscopy and electron paramagnetic resonance (EPR).…”

3D tomographic magnetofluorescence imaging of nanodiamonds

“…In this paper we pursue the development of a technique [1][2][3] that may in the future lead to biochemical 3D imaging in the animal or human body, in vivo. The method is based on the combination of fluorescent markers distributed within the body, having magnetic-field-dependent fluorescence efficiency, and an inhomogeneous magnetic field pervading the body.…”