54 SKIN CARE
40 30 20 10 0
Formula 14
ZnO ***
* TiO2
65 60 55 50 45
Formula 15
Formula 16
Formula 17
Formula 18
Formula 19
##
Formula 20
Figure 2: Enhancement of SPF by surfactin incorporation in physical sunscreen formulations. * p < 0.05, *** p < 0.001 vs. Formula 14. ## p < 0.01 vs. Formula 19
forces between particles.11 The concentration-dependent stabilization
effect, culminating in complete suspension stability at 1% surfactin, suggests optimal surface coverage was achieved at this concentration. The dramatic reduction in aggregate size,
particularly the transition of ZnO to sub- micron dispersion in water, represents a direct implication for UV protection efficiency. The 99% decrease in D50 value for ZnO indicates that surfactin effectively disrupts the strong interparticle forces that maintain large aggregates. This de-agglomeration significantly increases the specific surface area available for UV light interaction, which contributes to enhanced light scattering and absorption.12 The improved dispersion, achieved through
surfactin addition, leads to the substantial SPF boost in ZnO-based systems (up to 25%), greatly outperforming the commercial benchmark SG (1.6% improvement). The formulation protocol emerged as a key
factor: simultaneous dispersion of surfactin and UV filters in the aqueous phase was essential for optimal stabilization, enabling surfactin to interact directly with particle surfaces before oil-phase exposure, thus avoiding competitive adsorption and ensuring complete surface coverage.13 Parallel sensory enhancements—minimal
white cast, excellent spreadability, and a lighter, less tacky texture—directly reflected the reduced particle size of UV filter. The minimal white cast is explained by the
shift toward sub-micron effective diameters, which significantly decrease scattering in the visible range without compromising UV protection.14,15 Improved spreadability and absorption, in turn, arise from surfactin’s pronounced surface- activity, which lowers interfacial tension and facilitates the formation of a thin, uniform film upon application.16,17 This study provides a scientific foundation for surfactin as a performance enhancer for
10%ZnO (F14) ■ 10%ZnO+0.25%Surfactin (F16) ■ 10%ZnO+0.25%SG (F18) ■
Spreadability 8.0
7.0 6.0
Non-sticky afterfeel
micron-sized physical UV filters, future research should systematically address critical formulation considerations including long-term stability under diverse storage conditions and compatibility with other cosmetic ingredients. Additionally, exploring its efficacy across
different emulsion systems would facilitate broader industrial adoption. Such investigations would not only validate the technology’s robustness but also provide crucial insights for optimizing surfactin-containing formulations for specific market needs, ultimately accelerating the development of next-generation physical sunscreens that successfully balance performance, safety, and consumer acceptability.
Conclusion This study demonstrates that sodium surfactin effectively addresses key limitations of micron- sized TiO2
and ZnO sunscreens by enhancing
dispersion stability, UV protection efficiency, and sensory properties. The significant reduction in particle size (90% for TiO2
, 99% for ZnO) 10%TiO2 (F19) ■ 10%TiO2
Spreadability 7.5
5.5 3.5 +0.25%Surfactin (F20) ■
Lightness upon application
Non-sticky afterfeel
Lightness upon application
Figure 3: Sensory evaluation of surfactin-enhanced physical sunscreen PERSONAL CARE MAGAZINE March 2026
www.personalcaremagazine.com
Minimal white cast
Absorption rate
SPF
SPF
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