Boosting SPF with Lignin

Abstract

In cooperation with the Vienna University of Technology (TU WIEN), Lignovations GmbH has demonstrated that refining bulk lignin into Colloidal Lignin Particles (CLPs) yields a cosmetics-grade multifunctional that can boost the in-vivo SPF of sun protection products by up to 50% or 22 SPF points.

Issues of UV-Filters in Cosmetics Products

Solar exposure has multiple advantages, such as vitamin D synthesis and enhanced mental health ^1–3. However, excessive exposure without protection can result in dermatological conditions like sunburn, photoaging, and potentially, carcinogenesis ². In recent years, the safety of multiple organic UV filters ^{4 –6} has been called into question. Investigations have uncovered alterations in human reproductive anatomy and detrimental ecological and health effects ^7–12. Inorganic filters like Zinc Oxide and Titanium Dioxide are generally recognized as safe and effective (GRASE) by the ^FDA13. Nevertheless, these mineral-based filters present formulation challenges, potential aesthetic drawbacks in non-nanoparticulate forms, and ecological concerns at the nanoscale, particularly impacting marine ecosystems ¹⁴.
Innovation in this domain remains difficult due to high regulatory barriers as shown by the FDA’s approval of merely three new filters since 1978 ¹⁵. Therefore, to mitigate the limitations of UV
filters, SPF boosters are employed to increase UV filter efficiency, enabling a reduction in their concentration while maintaining or boosting SPF values.

Synthetic and Bio-Based SPF Boosters

The first SPF Boosters were developed for film formation and stabilizing UV filters, thereby increasing SPF efficacy ¹⁵. Current trends favor SPF boosters from natural sources ¹⁶ such as grape seed extract, jasmine, hibiscus, desert rose, propolis, aloe vera, yellow milfoil, and vetty fruit ^{6, 17}. However, the production of biobased SPF boosters often necessitates extensive cultivation and energy-intensive extraction methods, adversely affecting sustainability and cost-effectiveness ¹⁸. For a bio-based cosmetic ingredient to be genuinely sustainable, it should be abundantly available and exhibit properties highly relevant to the cosmetics sector.

Lignin – A Multifunctional SPF Boosting

Derived from the Latin term “lignum” meaning “wood,” Lignin is a highly diverse polyphenol [20] and a key structural component of terrestrial plants and algae. Lignin, the second most prevalent renewable biopolymer, is found in wood and woody plants and makes up 18–35% of plant biomass ²⁰. Lignin functions as a UV shield, a free radical scavenger, and reinforces secondary cell walls in plants.

With the rising demand for bio-based ingredients and the strategic importance of bio-based industries, new-generation biorefineries are becoming operational globally ²³. Unlike in traditional pulp mills, they do not burn lignin for energy but use modern processes that yield lignin in a near-native form without sulfur contamination, strong odors, or dark colors ^{18, 21, 22}. These new extraction methods also preserve lignin’s inherent functions, such as UV protection and antioxidative potential important for high-value applications ¹⁹.
However, even with advanced extraction techniques, raw or bulk Lignin is not suitable for use in cosmetic formulations ²⁴ because it is often characterized by particle sizes exceeding 10 μm,
irregular shapes, wide molecular weight distribution, and heterogeneous molecular structure^25,26 . Therefore, refining bulk Lignin is essential for its application in cosmetics.

Unlocking the Power of Lignin for Cosmetic Applications

To optimize the utility and effectiveness of regular lignin particles, they can be transformed into Colloidal Lignin Particles (CLPs), characterized by uniform, spherical shapes, a narrow molecular
weight range, and particle sizes less than 1 μm. These modifications enhance processability, dispersibility, performance, and uniformity, rendering them suitable for cosmetic formulations.
Scanning electron microscopy (SEM) images of bulk Lignin and CLPs demonstrate this transformation ^{27, 28} (Figure 1).
Comparative studies of emulsions using bulk Lignin and CLPs reveal that CLPs stabilize oil-in-water (o/w) emulsions, creating an evenly distributed particle network (Figure 1) compared to
bulk Lignin.

Advantages of Colloidal Lignin Particles in Sun Care Products

CLPs exhibit several advantageous properties for cosmetic applications, particularly in sun protection.

• Their small size and uniform distribution in sunscreen films enable enhanced reflection and scattering of sunlight ²⁹.
• Their predominantly hydrophilic surface properties (2) stabilize o/w emulsions by aligning at the oil-water interface, forming a robust droplet network.
• This leads to improved and uniform distribution of UV filters, thereby increasing their efficacy (Figure 2).
• Furthermore, their potent antioxidative properties stabilize UV filters and mitigate skin damage from UV exposure ³⁰.

A comparative analysis between typical bulk lignin and CLPs manufactured by Lignovations was conducted. Lignovations used a patented physical process to create CLPs with diameters ranging from 100–200 nm featuring high efficacy and enhanced dispersibility delivered in a stable water suspension (Figure 1).

The Importance of a Stable Colloidal System

To validate the SPF boosting potential of CLPs, an empirical methodology was adopted to determine the optimal formulation route for integrating aqueous CLPs into oil-in-water (o/w) cosmetic products.
Maintaining a stable colloidal system is crucial for ensuring uniform distribution of active particles. Precise particle sizing and purification in the production process result in stable aqueous suspensions of CLPs. Initial assessments evaluated the compatibility of these suspensions with common sunscreen ingredients, identifying the viscosity and conductivity of the aqueous phase as critical performance parameters. Favorable conditions include low viscosity and minimal salt concentration for incorporating CLPs.
Utilizing this knowledge, sunscreen formulations were developed incorporating a variety of inorganic and organic UV filters in the oil phase and CLPs in the aqueous phase. Optical microscopy, centrifugal testing, and in-vitro SPF assessments (based on DIN EN ISO24443) were conducted to evaluate the formulations.
It was observed that formulations containing CLPs had smaller oil droplets compared to control formulations without CLPs.
Long-term stability and resistance to phase separation and creaming were confirmed through centrifugal (3000 g/20 min/25 °C) and thermal (40 °C over 6 months) stability tests. This stability is attributed to the robust droplet network established and maintained by the CLPs (Figure 2).

In-vivo SPF Efficacy of Colloidal Lignin Particles

The in-vitro evaluations of sunscreens indicated promising SPF enhancement capabilities of CLPs for both organic and mineral filters. Subsequently, four sunscreen formulations with 2–3 wt% CLPs underwent in-vivo SPF testing to measure real-life SPF enhancement. These tests, conducted according to DIN EN ISO 24444 at an external institute, revealed SPF boosts up to
50% or 22 SPF points compared to control sunscreens (Figure 3).

Conclusion

The collaboration of Lignovations GmbH and Vienna University of Technology (TU Wien) has showcased a groundbreaking innovation in the field of sun protection with the application of
CLPs as SPF boosters in cosmetic products. As the cosmetic industry faces challenges related to the environmental impact, health concerns, and supply shortages associated with conventional UV filters, exploring sustainable alternatives is critical.
Lignin, derived from forestry and wood processing waste, emerges as a promising solution due to its abundance and the utilization of green chemistry techniques. The transformation of
Lignin into CLPs overcomes inherent hurdles, such as heterogeneity, making it a viable option for cosmetic applications.
The demonstrated increase in SPF efficacy of CLPs, achieving a 50% or 22-point SPF boost, highlights their potential to improve both the effectiveness and sustainability of sun protection products.
The successful demonstration of CLPs as SPF boosters not only marks a significant advancement in cosmetic technology but also aligns with the growing demand for sustainable and ecofriendly beauty solutions.

Based on the research, Lignovations has developed a commercial CLP dispersion marketed as LignoGuard. This multifunctional cosmetic ingredient is made from upcycled biomass and has received COSMOS and NaTrue approval. Furthermore, LignoGuard® has been selected as the winning ingredient of the IFSCC Sustainability Challenge (2023) and won at the Alle– Awards by Cosmetics & Toiletries (2024). Samples are available from Lignovations, including sample formulations and best practices using CLPs in cosmetic products as well as extensive technical and regulatory documentation.
For more information, visit www.lignovations.com.

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