Versatile strategy for achieving uniform molecular deposition in evaporation drops

Uniform evaporative deposition of non-volatile materials is crucial for applications such as electronic tattoos, crop spraying, textile dyeing, surface coating, and inkjet printing. However, achieving molecular uniformity remains challenging: small materials preferentially accumulate at the contact line, forming ring-like depositions due to weak inter-material attraction, low material-substrate adhesion, reduced geometric constraints, and enhanced flow influence. This study presents a versatile strategy for achieving uniform molecular deposition using cellulose nanofibers (CNFs). Experiments and theoretical analysis demonstrate that CNF percolation can cause steric hindrance and viscosity modulation to suppress- outward capillary flow, synergizing with strong molecular adsorption onto CNF surfaces, to ensure the uniform molecular deposition. This strategy is applicable across diverse substrates, including glass, leaves, ceramics, skin, polyethylene terephthalate, epoxy resin, wood, and porous cotton. Biomedical applications are demonstrated through a photodynamic antibacterial spray effective on porous media and a point-of-care bacterial counting method. These findings provide new insights into the suppression of the coffee-ring effect at the molecular level and establish a platform for uniform molecular deposition, with broad applications in biomedicine, electronics, agriculture, textiles, surface engineering, and materials science.