The use of immobilized enzymes in enhancing the biodegradability of cotton textiles is of great interest for sustainable textile waste management. Understanding how enzyme activity influences biodegradation rates is crucial for optimizing textile disposal strategies. This study aims to assess the impact of enzyme immobilization on the biodegradability of cotton fabrics, compared to microcrystalline cellulose and cotton treated with both active and inactivated enzymes. Biodegradability was evaluated by measuring CO₂ production over 75 days when the fabrics were buried in soil, as a proxy for microbial degradation. The study compared untreated cotton, cotton treated with immobilized enzymes, cotton with inactivated enzymes (via thermal treatment), and microcrystalline cellulose as reference. CO₂ emissions were monitored to quantify the biodegradation levels in each sample. The results indicated that microcrystalline cellulose exhibited the lowest biodegradability, with significantly lower CO₂ production. Among the cotton samples, the highest biodegradability was observed in the fabric treated with immobilized enzymes that had been inactivated by heat. This was followed by the cotton treated with active immobilized enzymes, while untreated cotton exhibited the lowest biodegradability of all the cotton samples. Although enzyme immobilization can enhance the stability and sustainability of degradation processes, thermal inactivation of enzymes unexpectedly increased biodegradation rates in cotton fabrics. This suggests that not only enzymes but others, such as structural changes in the cotton fibers, may play a role in facilitating biodegradation. Further research is needed increasing time and to clarify the mechanisms involved and optimize immobilization techniques for textile waste management.

The emergence of multi-resistant bacteria, untreatable with conventional medicines, is a significant global health concern. This study proposes a unique solution to this problem by digitally inkjet printing biomaterials bound with silver nanoparticles (NP) on cotton textiles. The silver nanoparticles, known for their effective antimicrobial properties, are stabilized, and made biocompatible by the enzymes. The use of digital inkjet printing allows for precise application of these NP-biomaterial conjugates, ensuring uniform coverage and optimal performance. This approach aims to prevent the spread of antimicrobial-resistant bacteria through cotton textiles in medical care environments, enhancing patient safety. The inkjet printing technology used in this study offers high-resolution patterning, enabling the creation of complex designs with multiple materials. This flexibility allows for the development of textiles with varying antimicrobial properties, tailored to specific applications in the medical field. Furthermore, the use of cotton, a natural and breathable material, ensures the comfort and safety of patients, making it an ideal choice for this application.

This chapter provides a comprehensive overview of wet processing techniques in the textile industry, emphasizing sustainability as a core theme. Wet processing encompasses a series of chemical and mechanical treatments that are designed to enhance fabric performance, aesthetics, and usability while addressing the industry's growing responsibility to minimize environmental impacts. The chapter is structured into distinct sections, each highlighting the processes, machinery, and sustainable practices that define modern textile finishing. Each section highlights emerging and alternative technologies along with helpful hints on innovation and marketing opportunities. 

The introduction outlines the scope and importance of wet processing, with a focus on the integration of sustainable technologies and eco-friendly practices in transforming raw textiles into functional and high-quality materials. The pre-treatment section discusses key preparatory steps, including desizing, scouring, and bleaching, and explores sustainable alternatives such as enzyme-based treatments and plasma treatments. The dyeing section examines the application of colour through traditional and innovative methods like foam and spray dyeing. The focus is on reducing resource consumption with approaches like plasma-enhanced dyeing and dyebath reuse. In the printing section, techniques such as screen, rotary, and digital printing are explored, emphasizing sustainable practices like reducing chemical waste through precision and automation. The finishing segment highlights mechanical finishes like compacting, brushing, sanforizing and heat-setting, along with chemical finishes such as water-repellence, flame retardants, anti-microbial properties and decorative denim washing. A focus is placed on using bio-based finishing agents and energy-efficient machinery to align with sustainability goals while enhancing fabric usability.

The structure of this chapter integrates theoretical concepts with industrial practices, offering a balance of scientific understanding and practical application. By the end of this chapter, readers will gain a holistic understanding of wet processing, its impact on textile properties, and its role in meeting industry and consumer expectations.

Lysozyme was inkjet printed on two different polyester fabrics considering several challenges of printing enzymes on synthetic fabric surfaces. Wettability of both the fabrics were improved by alkaline pre-treatment resulting reduction in water contact angle to 60±2 from 95°±3 and to 80°±2 from 115°±2 for thinner and coarser fabric respectively. Activity of lysozyme in the prepared ink was 9240±34 units/ml and reduced to 5946±23 units/ml as of collected after jetting process (before printing on fabric). The formulated ink was effectively inkjet printed on alkali treated polyester fabric for antimicrobial applications. Retention of higher activity of the printed fabric requires further studies on enzyme-fibre binding mechanisms and understanding protein orientation on fabric surface after printing

This thesis explores the possibilities of printing enzymes using resource-efficient technologies to promote the binding of other proteins and biomaterials on synthetic textiles. This strategy can be used to develop advanced textiles for applications, for example, in antimicrobial, drug delivery and biosensing. Digital inkjet printing was combined with enzyme technology to ensure minimum use of water, chemicals and energy in textile manufacturing processes.  

Inks containing two enzymes, lysozyme and tyrosinase, were formulated by adjusting several rheological and ionic properties. The activity of these enzymes was optimised while being printed through two different industrial grade piezoelectric printheads. The theoretical printability of the prepared inks was calculated. The effect of printhead temperature and number of printing passes on the activity was evaluated. Polyester (polyethylene terephthalate) and polyamide-6,6 were pre-treated through several techniques to understand their effect on enzyme adhesion, binding and activity retention. Tyrosinase was used to bind lysozyme on plasma activated polyamide-6,6 surface. The effects of printing these two enzymes in various sequences, i.e. tyrosinase before lysozyme and vice-versa on binding stability and activity, were studied. Influence of the printing process on enzyme kinetics was evaluated. Ability to store and reuse printed fabrics was also studied.  

Lysozyme and tyrosinase containing inks showed activity retention of 85% and 60%, respectively. Activity of lysozyme containing ink was optimum at 10–15 mPa.s when glycerol was used as a viscosity modifier. However, the optimum viscosity for tyrosinase containing ink was at 6–9 mPa.s, and carboxymethyl cellulose was found to be the most favourable modifier. For both inks, a surfactant amount below the critical micelle concentration was considered to be the most effective for printing. Among the studied fabric pre-treatment methods (alkaline, cutinase and plasma), it was found that the activity and stability of the enzyme were dependent on the nature of the pretreatment processes, which can be beneficial for different application areas, e.g. drug release and bio-sensing. Upon printing both inks on a plasma treated polyamide-6,6, tyrosinase was able to catalyse lysozyme protein to bind it on fabric. A maximum of 68% lytic activity was retained by lysozyme when it was printed after tyrosinase. This fabric showed inhibition of bacterial growth and retained almost half of its initial activity when cold stored for a month. 

Enzymes can be immobilized on textiles to impart anti-microbial properties in a more environment-friendly manner compared to conventional biocide-based solutions. Such application requires ensuring precise, flexible and contamination-free immobilization methods that can be offered by digital printing compared to coating or screen-printing techniques. Drop-on-demand inkjet printing is a resource-efficient technology that can ensure these requirements. The use of polyester and polyamide-based fabrics is rising for applications ranging from apparel and home furnishing to hygiene and medical textiles. These fibers offer superior chemical, physical, and mechanical properties due to their inert nature but challenge the printing process due to hydrophobicity and lack of functional groups. Lysozyme and tyrosinase are two enzymes showing great potential for grafting on synthetic fabrics paving the way to use them for inkjet printing as well.

Challenges for inkjet printing of enzymes on synthetic fabric surfaces come in multiple forms i.e. ink recipe formation, printer mechanics and fabric surface characteristics. The ink must maintain a suitable viscosity and surface tension for effective drop ejection and a feasible ionic nature for enzyme activity. Then, the enzyme must be able to sustain the temperature and shear stress generated inside an inkjet printhead. Finally, influential fabric characteristics include surface structure, pore size distribution, evaporation rate and binding mechanism. By considering these parameters, lysozyme and tyrosinase were successfully printed on variously modified synthetic fabrics using a combination of sustainable technologies.

Tyrosinase enzyme was digitally printed on plasma pretreated polyamide-6,6 fabric using several sustainable technologies. Ink containing carboxymethyl cellulose was found to be the most suitable viscosity modifier for this enzyme. Before and after being deposited on the fabric surface, the printed inks retained enzyme activity of 69% and 60%, respectively, compared to activity prior printing process. A good number of the printed enzyme was found to be strongly adsorbed on the fabric surface even after several rinsing cycles due to surface activation by plasma treatment. Rinsed out fabrics retained a maximum activity of 34% resulting from the well-adsorbed enzymes. The activity of tyrosinase on printed fabrics was more stable than ink solution for at least 60 days. Effects of pH, temperature and enzyme kinetics on ink solution and printed fabrics were assessed. Tyrosinase printed synthetic fabrics can be utilized for a range of applications from biosensing and wastewater treatment to cultural heritage works.

An ink containing tyrosinase catalyzes the tyrosine residues on lysozyme protein to bind it on a plasma-treated polyamide-6,6 (PA) fabric. Inkjet printing enables controlled and sequential deposition of two enzymes on PA which is necessary for proper binding. The effect of different printing sequences on crosslinking stability and enzymatic activity is presented. The lysozyme bound on the fabric shows satisfactory antimicrobial activity. The printed fabric retains about 68% of the ink activity when tyrosinase is printed before lysozyme. Further, this fabric retains about 24% of the initial activity up to four reuses. The fabric shows acceptable inhibition of bacterial growth and retains almost half of its initial activity when cold stored for a month. This work shows the potential of protein binding on textile surface using various means of sustainable technologies, namely enzyme, inkjet, and plasma. 

Enzymes immobilized on synthetic polyethylene terephthalate (PET) textile surface by resource‐efficient inkjet printing technology can promote developments for various novel applications. Synthetic fabrics often require adequate pretreatments to facilitate such printing process. This work discusses PET–woven fabric pretreatment routes to improve wettability by alkaline, enzymatic, and plasma processes for effective printing of lysozyme using an industrial piezoelectric printhead. Results indicate that all pretreated samples contain a similar amount of enzymes upon printing. Plasma treated fabrics show relatively more hydrophilic surface characteristics, better protein binding stability, and lower retained activity. Alkali and cutinase‐treated samples possess relatively higher activity due to the greater amount of enzyme desorption to substrate solution. Depending on respective enzyme‐binding stability, a combination of a well-pretreated surface and inkjet as preferential placement technology, the approach of this study can be used as a facile enzyme immobilization method for suitable applications, for example, controlled‐release and bio‐sensing.