Multiphoton microscopy (MPM) imaging of intrinsic two-photon excited fluorescence (TPEF) is performed on humanized sickle cell disease (SCD) mouse model splenic tissue. Distinct morphological and spectral features associated with SCD are identified and discussed in terms of diagnostic relevance. Specifically, spectrally unique splenic iron-complex deposits are identified by MPM; this finding is supported by TPEF spectroscopy and object size to standard histopathological methods. Further, iron deposits are found at higher concentrations in diseased tissue than in healthy tissue by all imaging methods employed here including MPM, and therefore, may provide a useful biomarker related to the disease state. These newly characterized biomarkers allow for further investigations of SCD in live animals as a means to gain insight into the mechanisms impacting immune dysregulation and organ malfunction, which are currently not well understood.
We present our study on compact, label-free dissolved lipid sensing by combining capillary electrophoresis
separation in a PDMS microfluidic chip online with mid-infrared (MIR) absorption spectroscopy for biomarker
detection. On-chip capillary electrophoresis is used to separate the biomarkers without introducing any extrinsic
contrast agent, which reduces both cost and complexity. The label free biomarker detection could be done by
interrogating separated biomarkers in the channel by MIR absorption spectroscopy. Phospholipids biomarkers of
degenerative neurological, kidney, and bone diseases are detectable using this label free technique. These
phospholipids exhibit strong absorption resonances in the MIR and are present in biofluids including urine, blood
plasma, and cerebrospinal fluid. MIR spectroscopy of a 12-carbon chain phosphatidic acid (PA) (1,2-dilauroyl-snglycero-
3-phosphate (sodium salt)) dissolved in N-methylformamide, exhibits a strong amide peak near
wavenumber 1660 cm<sup>-1</sup> (wavelength 6 μm), arising from the phosphate headgroup vibrations within a low-loss
window of the solvent. PA has a similar structure to many important phospholipids molecules like
phosphatidylcholine (PC), phosphatidylinositol (PI), phosphatidylethanolamine (PE), phosphatidylglycerol (PG),
and phosphatidylserine (PS), making it an ideal molecule for initial proof-of-concept studies. This newly proposed
detection technique can lead us to minimal sample preparation and is capable of identifying several biomarkers from
the same sample simultaneously.