Here we report a new low temperature dry ice carbonation approach for the synthesis of carbonate-based nano- and micro-particulate materials, which enables the preparation of monodispersed calcium carbonate nanoparticles and microspheres with very high purity phases.
The
efficient and sensitive detection of pathogenic microorganisms
in aqueous environments, such as water used in medical applications,
drinking water, and cooling water of industrial plants, requires simple
and fast methods suitable for multiplexed detection such as flow cytometry
(FCM) with optically encoded carrier beads. For this purpose, we combine
fluorescent Cd-free Ag–In–S ternary quantum dots (t-QDs)
with fluorescence lifetimes (LTs) of several hundred nanoseconds and
superparamagnetic Fe3O4 nanoparticles (SPIONs)
with mesoporous CaCO3 microbeads to a magneto-fluorescent
bead platform that can be surface-functionalized with bioligands,
such as antibodies. This inorganic bead platform enables immuno-magnetic
separation, target enrichment, and target quantification with optical
readout. The beads can be detected with steady-state and time-resolved
fluorescence microscopy and flow cytometry (FCM). Moreover, they are
suited for readout by time gated emission. In the following, the preparation
of these magneto-fluorescent CaCO3 beads, their spectroscopic
and analytic characterization, and their conjugation with bacteria-specific
antibodies are presented as well as proof-of-concept measurements
with Legionella pneumophila including cell cultivation
and plating experiments for bacteria quantification. Additionally,
the possibility to discriminate between the long-lived emission of
the LT-encoded capture and carrier CaCO3 beads and the
short-lived emission of the dye-stained bacteria with time-resolved
fluorescence techniques and single wavelength excitation is demonstrated.
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