Optimization
of PdPt alloys for metabolite detection. SEM images
of (a) PdPt-1, (b) PdPt-2, (c) PdPt-3, and (d) PdPt-4 alloys with
different particle sizes. (e) Intensities of sodium- and potassium-adducted
signals of glucose (Glc), phenylalanine (Phe), arginine (Arg), and
proline (Pro) detected by PdPt-1/2/3/4 alloy-assisted LDI MS. The
error bars were determined as the standard deviation (s.d.) of nine
measurements. Contour plots of (f) electric field amplitudes and (g)
thermal field distribution shown on the color scale for (i) PdPt-1,
(ii) PdPt-2, (iii) PdPt-3, and (iv) PdPt-4 alloys, for a 355 nm laser
beam with polarization along the Y axis. Laser light
was introduced along the Z-axis. The electric field
amplitudes and thermal field distribution were counted by the finite
element method. (h) Typical mass spectrometry of different metabolites
(Pro, asparagine (Asn), Phe, Arg, Glc and sucrose (Suc)) in water
solution, detected by PdPt-2 alloys assisted LDI MS. (i) Coefficient
of variance (CV) distribution of different metabolites (Pro, Asn,
Phe, Arg, Glc and Suc) analyzed by PdPt-2 alloys assisted LDI MS.
The results come from nine independent experiments. (j) Typical mass
spectrometry of different metabolites (Pro, Asn, Phe, Arg, Glc, and
Suc) in a mixture solution of 0.5 M NaCl (salt tolerance detection)
and 5 mg mL–1 bovine serum albumin (protein endurance
detection), detected by PdPt-2 alloy-assisted LDI MS. Scale bar: (a,
b, c, d) 100 nm.