Fig. 1 EDS spectra of a P1, b P2, c P3, d P3 synthesized at alkaline pH

Fig. 2 a XRD patterns of P1, P2, P3, bM-H curves of P1, P3 and Pt particles, c exchange bias in P1, dM-H curve of P2, eM-T curve of P2

Fig. 3 a, c, e HR-TEM images (insets showing the FFT images of single crystalline particles), b, d, f SAED patterns (insets showing the size distribution of particles) of P1, P2 and P3, respectively

Fig. 4 FTIR spectra of a P1, b P2, c P3

Fig. 5 a Decomposition of H2O2 using P2 indicated by increasing absorbance of ROS-sensitive DCF. Here samples 1, 2, 3, 4 and 5 are designated by the amount of P2 used as 50, 100, 150, 200 and 250 μL of a solution of concentration 1 mg/mL. Inset shows the plot between absorbance of the indicator dye against nanoparticle concentration. b, c Fluorescence micrographs of control and sample 5

Fig. 6 In vitro cytotoxicity evaluated by MTT assay using Hella cells in the range of 0-20 μg/mL iron-platinum nanoparticles after incubation time of 24 h

Fig. 7 a Transverse relaxation time (T2), b transverse relaxation rate (R2 = 1000/T2) with varying concentration of P2. The slope of the line in panel b indicates the relaxivity. T2-weighted magnetic resonance images of mouse abdomen pre c, d-, post e, f-administration of P2. Hypointensity in liver following administration of P2 is indicated with white arrowse, f