Multifunctional Nanotemplates of Nd³⁺-Doped Ln₂S₃ (Ln = Pr, Sm, Gd) Nanoflowers Coated with Graphene Oxide for Enhanced Biocompatibility, Biomolecular Interaction Optimization, and Photocatalytic Dye Reduction

Despite the considerable advancements in Ln2S3-based nanomaterial, considerable challenges persist in the development of multifunctional nanotemplates that are simultaneously effective in biomedical and environmental applications. Herein, this study outlines the synthesis of Ln2S3 (Ln = Pr, Sm, Gd) that was doped with Nd3+ as Nd-Ln2S3 and thereafter precisely coated with graphene oxide (GO), producing Nd-Ln2S3@GO nanotemplates. Structural integrity was validated through XRD, FTIR, Raman, TGA/DTG, FESEM, EDX, HR-TEM, AFM, and XPS. Nd-Ln2S3@GO nanotemplates demonstrated significant enhancement in the proliferation of MCF-7 breast cancer cells. The MCF-7 cell viabilities were recorded to be 91.6, 91.5, and 90.0% for Nd-Pr2S3@GO, Nd-Sm2S3@GO, and Nd-Gd2S3@GO for 80 μg mL–1, respectively, proving their biocompatibility as potential nanocarriers in drug delivery. Biocompatibility improvements of 71.70, 33.19, and 16.13% were accomplished by shifting Pr2S3, Sm2S3, and Gd2S3 to Nd-Pr2S3@GO, Nd-Sm2S3@GO, and Nd-Gd2S3@GO, respectively. Their first-order ρ, η, γ, σ, and ksϕ physicochemical and Ea, ΔGb, ΔGs, ΔS, and ΔH thermodynamic properties with bovine serum albumin (BSA), hemoglobin (Hb), and double-stranded DNA (dsDNA) at physiological temperature 310.15 K revealed infinitesimal interactions with salt bridges (SBs) of proteins and base pairs (BPs) of dsDNA. The >4 mg% Nd-Ln2S3@GO physiosorbed 2 mg of protein with weak protein–water interactions acted as a protein separator or adsorbent for protein therapy. The processes of doping and coating resulted in a reduction of the band gap energy (Eg) from 4.94 to 3.34 eV, associated with an increase in UV–vis absorption. The shift from Pr2S3, Sm2S3, and Gd2S3 to Nd-Pr2S3@GO, Nd-Sm2S3@GO, and Nd-Gd2S3@GO achieved a time reduction for photocatalytic reduction (PCR) and removal of methylene blue (MB) dye from 1283, 1283, and 1370 to 63, 45, and 45 min (96.10% acceleration) with a quantum yield (ϕ) of 99%, respectively. Consequently, Nd-Ln2S3@GO of all Pr, Sm, and Gd metals were validated as multifunctional nanotemplates for drug delivery nanocarriers, optimization of biomolecular interactions, and photocatalytic removal of wastewater effluents.