Polydopamine‐Modified 2D Iron (II) Immobilized MnPS3 Nanosheets for Multimodal Imaging‐Guided Cancer Synergistic Photothermal‐Chemodynamic Therapy

Abstract Manganese phosphosulphide (MnPS3), a newly emerged and promising member of the 2D metal phosphorus trichalcogenides (MPX3) family, has aroused abundant interest due to its unique physicochemical properties and applications in energy storage and conversion. However, its potential in the field of biomedicine, particularly as a nanotherapeutic platform for cancer therapy, has remained largely unexplored. Herein, a 2D “all‐in‐one” theranostic nanoplatform based on MnPS3 is designed and applied for imaging‐guided synergistic photothermal‐chemodynamic therapy. (Iron) Fe (II) ions are immobilized on the surface of MnPS3 nanosheets to facilitate effective chemodynamic therapy (CDT). Upon surface modification with polydopamine (PDA) and polyethylene glycol (PEG), the obtained Fe‐MnPS3/PDA‐PEG nanosheets exhibit exceptional photothermal conversion efficiency (η = 40.7%) and proficient pH/NIR‐responsive Fenton catalytic activity, enabling efficient photothermal therapy (PTT) and CDT. Importantly, such nanoplatform can also serve as an efficient theranostic agent for multimodal imaging, facilitating real‐time monitoring and guidance of the therapeutic process. After fulfilling the therapeutic functions, the Fe‐MnPS3/PDA‐PEG nanosheets can be efficiently excreted from the body, alleviating the concerns of long‐term retention and potential toxicity. This work presents an effective, precise, and safe 2D “all‐in‐one” theranostic nanoplatform based on MnPS3 for high‐efficiency tumor‐specific theranostics.


Calculation of the photothermal conversion efficiency (𝜂):
Following Roper's report, [1] we calculate the photothermal conversion efficiency (η) of Fe-MnPS3/PDA-PEG nanosheets by using the following equation ( 1): η = (hS(Tmax-Tsurr)-Qdis)/I(1-10 -A ) (1)   where h is the heat transfer coefficient, S is the surface area of the container.Tmax is the equilibrium temperature, Tsurr is the surrounding ambient temperature, and Qdis represents the heat dissipated by the solvent measured independently using a quartz cuvette. [2]I is the laser power density, and A is the absorbance of Fe-MnPS3/PDA-PEG nanosheets at 808 nm.In equation ( 1), only the hS remains unknown.The value of hS can be derived following equation (2) ~ equation (4): where θ represents the dimensionless driving force temperature, and T is the instant temperature during the cooling time (t).τs is the sample system time constant, which is determined to be 274 s. m and Cp are the mass (1 g) and heat capacity (4.2 J g -1 ) of the aqueous solution, respectively.
Thus, hS can be calculated to be 15.3 mW/°C.Then, the photothermal conversion efficiency (η) of Fe-MnPS3/PDA-PEG nanosheets is calculated to be 40.7%.

Figure S2 .
Figure S2.Statistical analysis of the lateral size of MnPS3 nanosheets obtained from the SEM images.

Figure S3 .
Figure S3.a) AFM image of Fe-MnPS3 nanosheets.b) Height profiles of Fe-MnPS3 nanosheets along the white lines in a).

Figure S9 .
Figure S9.Photographs of MnPS3 (i) and Fe-MnPS3 (ii) dispersed in water for 0 h and 12 h.

Figure S13 .
Figure S13.Photographs of the Fe-MnPS3/PDA-PEG nanosheets dispersed in different solvents for 0 h and 72 h.

Figure S14 .
Figure S14.a) Size changes of Fe-MnPS3/PDA-PEG nanosheets before and after NIR irradiation.b) Absorbance spectra of Fe-MnPS3/PDA-PEG nanosheets before and after NIR irradiation.Inset: the corresponding photographs.

Figure S15 .
Figure S15.Quantified Mn ions released from Fe-MnPS3/PDA-PEG nanosheets under different pH and temperature conditions.

Figure S18 .
Figure S18.a) Bright-field images of MCF7 cells before and after uptake of Fe-MnPS3/PDA-PEG nanosheets.b) Quantitative determination of MCF7 cell uptake of Fe-MnPS3/PDA-PEG nanosheets at different concentrations.The scale bar is 100 μm for all images.

Figure S19 .
Figure S19.Bright-field and their merged images of MCF7 cells after different treatments.DCFH-DA is employed to detect the generation of hydroxyl radicals (•OH) through the observation of green fluorescence.Scale bar = 50 μm.

Figure S22 .
Figure S22.a) Fluorescence images of MCF7 tumor-bearing nude mice administrated with free Cy5.5 at different time intervals.b) Quantification of fluorescence intensity in tumor areas after the injection of free Cy5.5 by using ROI.

Figure S23 .
Figure S23.Semi-quantitative analysis of the MRI-signal intensity in tumor areas by assessing the average pixel brightness value after (a) intratumoral or (b) intravenous injection of Fe-MnPS3/PDA-PEG nanosheets at 0, 2, and 6 h, respectively.

Figure S24 .
Figure S24.Photographs of MCF7 tumor-bearing mice and tumor regions after different treatments for 14 days.

Figure S25 .Figure S26 .
Figure S25.a) Typical photographs of MCF7 tumor-bearing mice after different treatments for 14 days.b) Time-dependent tumor growth curves in different groups of mice.

Figure S27 .
Figure S27.a) Blood biochemistry data of the mice after intravenous injection of Fe-MnPS3/PDA-PEG nanosheets for 14 days with parameters including ALT, AST, BUN, and CREA.b) Blood routine analysis of the mice after intravenous injection of Fe-MnPS3/PDA-PEG nanosheets for 14 days.The following parameters were measured: WBC, RBC, HGB, HCT, MCV, MCH, MCHC, and PLT.