Project Description

Inspiration of the Project: Xiangyunsha

Rooted in Hangzhou’s Dyeing Heritage

Nested in the heart of Hangzhou, a city celebrated for centuries of silk excellence and the ecological wisdom of Xiangyunsha dyeing, our journey began with a clear vision and a pressing challenge. We recognized the immense potential of bio-enzyme dyes as a sustainable alternative to chemical colorants in the textile and personal care sectors. However, a critical bottleneck stood in the way of their commercial adoption: while their environmental benefits were widely acknowledged, their practical application was severely limited by a narrow and unreliable color spectrum. This challenge became the catalyst for our innovation.

Industrial Textile Dyes: Major Types and Applications

A Market Dominated by Synthetics

The global textile dye market is overwhelmingly dominated by synthetic dyes due to their cost efficiency, superior color fastness, and broad chromatic range [1]. This sector represents a critical segment of the broader $44.41 billion dyes and pigments industry in 2024, projected to reach $87.99 billion by 2037 at a 5.4% compound annual growth rate (CAGR) [2].

The era of synthetic dyes began in 1856 with William Perkin’s serendipitous synthesis of mauveine. Today, azo dyes (‑N=N‑ bonds) constitute 60–70% of synthetics but face scrutiny for potential release of carcinogenic aromatic amines [3,4]. Anthraquinone dyes are valued for their superior lightfastness [5]. Dyes are also classified by their application methods, such as Disperse dyes for polyester, Acid dyes for protein fibers like wool and silk, and Reactive dyes for cellulose, each requiring specific process conditions [6].

Environmental and Health Impacts of Conventional Synthetic Dyes

A Heavy Burden on Ecosystems

Conventional synthetic dyes pose severe ecological and public health threats. Approximately 10–15% of dyes used in textile processing are discharged untreated into waterways globally, releasing over 700,000 tons of dye-laden effluents each year [3,8]. Azo dyes can degrade into carcinogenic aromatic amines that bioaccumulate in aquatic systems and human food chains [9]. Heavy metals such as chromium and cadmium, used as mordants, further contaminate water and soil [10].

The complex structures of synthetic dyes make them highly resistant to conventional wastewater treatments, which typically achieve low removal efficiency for highly soluble dyes [11]. Advanced treatment methods exist but are energy-intensive or generate secondary waste [12,13]. Additionally, dyeing processes consume 150–250 liters of water per kilogram of fabric and generate extreme pH waste streams [12], challenging sustainability goals.

Natural Dyes: Diversity and Limitations

Ecological Benefits with Practical Constraints

Natural dyes derived from botanical, animal, or microbial sources are valued for their biodegradability and low toxicity [15,16]. They can also offer functional properties such as UV resistance [16,17]. Despite these advantages, industrial adoption is limited by seasonal variability, geographic constraints, low extraction yields, and inconsistent supply chains [3,15].

Performance challenges include weak color fastness and reproducibility without toxic metal mordants, leading to rapid fading under light exposure or washing. Technological bottlenecks in extraction and application further limit scalability [18]. These constraints highlight the need for a scalable, reliable, and green alternative.

Our Solution: Engineered Biocatalysis for Sustainable Dyeing

Reusable Enzymatic Nanofactories

We developed an innovative biocatalytic platform centered on Bacillus megaterium tyrosinase (TyrBm) fused to the self-assembling scaffold protein CipA from Photorhabdus luminescens [19,20]. Expressed in E. coli, the TyrBm-CipA fusion assembles into reusable enzymatic nanofactories that simplify purification and maintain high catalytic activity through multiple cycles.

These immobilized enzymes efficiently oxidize tyrosine derivatives, such as Boc-L-tyrosine, into non-toxic, melanin-inspired pigments spanning earthy browns to vibrant reds [21,22]. The platform eliminates reliance on carcinogenic azo dyes and heavy metals, drastically reduces water consumption, avoids extreme pH effluent, and retains >70% activity after seven or more catalytic cycles [20]. Integrating synthetic biology with green chemistry delivers a scalable, circular solution for textile coloration.