What Are the Different Applications for Polyhydroxyalkanoates (PHAs)?

By Olivebio 

Polyhydroxyalkanoates (PHAs) are a remarkable class of biodegradable polymers with a wide range of applications. From more ecologically-friendly packaging materials to cutting-edge medical advancements, PHAs are helping shape the future of materials science. In this blog, we will explore the diverse applications of PHAs and delve into their incredible versatility, shedding light on how these biopolymers have the potential to revolutionize a variety of industries.

Applications for Polyhydroxyalkanoates (PHAs)

Biomedical applications

PHAs are biocompatible, non-toxic, and biodegradable—qualities that make them well-suited to a range of biomedical applications (See Figure 1). In addition, their local pH value does not change during degradation, which makes them better tolerated by cells and the immune system than other clinically used polymers such as poly(lactic acid) (PLA), poly(ε-caprolactone) (PCL), poly(lactide-co-glycolide) (PLGA) and poly(glycolic acid) (PGA) (Rodriguez-Contreras, 2019, Koller, 2018).

Figure 1: Applications for polyhydroxyalkanoates (PHAs) in the biomedical field. Source: Pulingam et al., 2022. Biomedical Applications of Polyhydroxyalkanoate in Tissue Engineering. Polymers, 14(11), 2141. MDPI AG. Retrieved from http://dx.doi.org/10.3390/polym14112141

Examples of the biomedical applications for PHAs include:
  • Biodegradable sutures and surgical staples: PHAs can be processed into sutures and surgical staples that are absorbed by the body over time, reducing the need for a second surgery to remove them. This promotes wound healing and reduces the risk of infection (Chen & Wu, 2005).
  • Drug delivery systems: PHAs can be used to create drug delivery systems, such as nanoparticles and microspheres, that can encapsulate and release drugs in a controlled manner. This enables sustained drug release and targeted therapy (Zinn et al., 2001).
  • Tissue engineering and regenerative medicine: PHAs can serve as scaffolds for tissue engineering applications. They have a high immunological tolerance and provide a biocompatible and biodegradable platform for the growth and regeneration of tissues, such as bone, cartilage, and skin (Możejko-Ciesielska & Kiewisz, 2016; Guo et al., 2022).
  • Implants and prosthetics: PHAs can be used to create non-toxic and biodegradable implants, such as bone plates, screws, and stents, which gradually degrade in the body as the tissues heal or regenerate. This eliminates the need for removal surgeries (Chen & Wu, 2005; Kalia et al, 2021).
  • Dermal fillers and cosmetic surgery: PHAs have been explored as biocompatible materials for dermal fillers and cosmetic surgery applications. They can provide volume and support to tissues and gradually degrade over time.
  • Wound dressings: PHAs can be used to manufacture biodegradable wound dressings that promote healing while reducing the risk of infection, as they can be tailored to release antimicrobial agents. Incorporating antibiotics, metal nanoparticles, and other materials chemically into PHA films can generate a composite blend with antimicrobial properties. In addition, some degradation products of PHA hydrolysis can induce an inhibitory effect on microbial growth (de Souza & Shivakumar, 2019; Guo et al., 2022).
  • Diagnostic tools: PHA-based microarrays and biosensors have been developed for diagnostic purposes, such as detecting biomarkers and pathogens. These can be valuable tools in healthcare (Rehm et al., 2017).
Other applications for PHAs can be found in the dental health field, where they are used as barrier material for tissue regeneration in cases of periodontitis, or as urological stents in the field of urology (Zinn et al., 2001). These applications and many more, such as for injectables, nanofibers, and making artificial nerve conduits, blood vessels, and heart valves all demonstrate the versatility of PHAs in the biomedical field, including their biodegradability, biocompatibility, and tunable properties that make them ideal materials for various medical devices and therapies (Zhang et al., 2017). The development and commercialization of PHA-based biomedical products are ongoing, and research in this field continues to evolve.

Agricultural applications

The properties of PHAs also make them suitable for several applications in agriculture, including the following:

  • Biodegradable sutures and surgical staples: PHAs can be processed into sutures and surgical staples that are absorbed by the body over time, reducing the need for a second surgery to remove them. This promotes wound healing and reduces the risk of infection (Chen & Wu, 2005).
  • Drug delivery systems: PHAs can be used to create drug delivery systems, such as nanoparticles and microspheres, that can encapsulate and release drugs in a controlled manner. This enables sustained drug release and targeted therapy (Zinn et al., 2001).
  • Tissue engineering and regenerative medicine: PHAs can serve as scaffolds for tissue engineering applications. They have a high immunological tolerance and provide a biocompatible and biodegradable platform for the growth and regeneration of tissues, such as bone, cartilage, and skin (Możejko-Ciesielska & Kiewisz, 2016; Guo et al., 2022).
  • Implants and prosthetics: PHAs can be used to create non-toxic and biodegradable implants, such as bone plates, screws, and stents, which gradually degrade in the body as the tissues heal or regenerate. This eliminates the need for removal surgeries (Chen & Wu, 2005; Kalia et al, 2021).
  • Dermal fillers and cosmetic surgery: PHAs have been explored as biocompatible materials for dermal fillers and cosmetic surgery applications. They can provide volume and support to tissues and gradually degrade over time.
  • Wound dressings: PHAs can be used to manufacture biodegradable wound dressings that promote healing while reducing the risk of infection, as they can be tailored to release antimicrobial agents. Incorporating antibiotics, metal nanoparticles, and other materials chemically into PHA films can generate a composite blend with antimicrobial properties. In addition, some degradation products of PHA hydrolysis can induce an inhibitory effect on microbial growth (de Souza & Shivakumar, 2019; Guo et al., 2022).
  • Diagnostic tools: PHA-based microarrays and biosensors have been developed for diagnostic purposes, such as detecting biomarkers and pathogens. These can be valuable tools in healthcare (Rehm et al., 2017).
Other applications for PHAs can be found in the dental health field, where they are used as barrier material for tissue regeneration in cases of periodontitis, or as urological stents in the field of urology (Zinn et al., 2001). These applications and many more, such as for injectables, nanofibers, and making artificial nerve conduits, blood vessels, and heart valves all demonstrate the versatility of PHAs in the biomedical field, including their biodegradability, biocompatibility, and tunable properties that make them ideal materials for various medical devices and therapies (Zhang et al., 2017). The development and commercialization of PHA-based biomedical products are ongoing, and research in this field continues to evolve.

Packaging applications

PHAs can be used to manufacture biodegradable packaging materials such as bags, films, and containers. They have good barrier properties, which makes them suitable for a range of packaging applications, including food containers, bags, and films (Bugnicourt et al., 2014). As versatile materials that can be composted, they have the potential to reduce the environmental impact of conventional petroleum-based plastics, which are ubiquitously used in packaging. 

Some of the different packaging applications for PHAs include (Bugnicourt et al., 2014; Adeleye et al., 2020; Koller, 2014; Sehgal & Gupta, 2020):

  • Single-use plastic bags: PHAs can be used to manufacture single-use plastic bags as a biodegradable and compostable alternative to traditional plastic bags.  
  • Food packaging: PHAs can be used in food packaging materials such as films, storage bags, and containers.
  • Disposable cutlery, tableware, and straws: PHAs can replace traditional disposable plastic cutlery, plates, and cups. They can also be used to manufacture biodegradable straws as an alternative to single-use plastic straws (Koller & Mukherjee, 2022).
  • Bottles and containers: PHAs can be used to manufacture bottles and containers for various products, including cosmetics, personal care products, and household items.
  • Biodegradable packaging fillers: PHA-based foam or filler materials can be used for protective packaging in shipping and logistics. They can replace traditional foam peanuts and reduce packaging waste.
  • Textile packaging: PHAs can be used in textile packaging materials for protection during shipping and storage (Pandey et al., 2022).
  • Electronics packaging: PHAs have anti-static properties and can be used for protective packaging of electronic components.
  • Biodegradable films and wraps: PHAs can be used to create stretch films and wraps for both industrial and household use. 
  • Biodegradable bags for waste collection: PHA-based bags can be used for waste collection, and they can be composted along with the waste under the right conditions.
Pharmaceutical and medical device packaging: Non-toxic PHAs offer good barrier properties and can be used in pharmaceutical packaging, including capsules, blister packs, and vials. They are also used in the packaging of medical devices and instruments.

Textile industry applications

While not as widely used as traditional synthetic polymers, PHAs have found applications in the textile industry. Here are some of the different textile applications for PHAs:

  • Biodegradable textiles and fibers: PHAs can be processed into fibers that are suitable for textiles. These biodegradable fibers can be used in the production of a wide range of textile products, including clothing, bags, and accessories (Pandey et al., 2022). They offer the advantage of being compostable and reducing the accumulation of non-degradable plastic waste in landfills. 
  • Bio-based coatings: PHAs can be used as bio-based coatings for textiles. These coatings can provide various functionalities to textiles, such as water repellency, UV resistance, and antimicrobial properties. They offer a sustainable alternative to conventional chemical coatings that may have negative environmental impacts. 
  • Biodegradable filament for 3D printing: PHAs can be used as a feedstock for 3D printing filaments. This filament can be used to produce customized textile-like structures and clothing items using additive manufacturing techniques. These 3D-printed textiles can be biodegradable and offer design flexibility (Koller et al., 2005). 
  • Biodegradable non-woven fabrics: PHAs can be used to produce non-woven fabrics, which find applications in various industries, including textiles. Biodegradable non-woven fabrics made from PHAs can be used in products like disposable clothing, hygiene products, and agricultural textiles (Pandey et al., 2022).

While PHAs offer biodegradability and sustainability advantages, their adoption in the textile industry is still relatively limited compared to traditional synthetic polymers. Research and development efforts are ongoing to improve the properties and cost-effectiveness of PHA-based textiles for wider commercial use.

There are also some interesting efforts in the fashion industry, such as Amsterdam’s “Fashion for Good” that plans to launch a Renewable Carbon Textiles Project. This project will focus on technical feasibility studies, melt-spinning trials, and environmental degradation testing with the goal of accelerating the development of PHA fibers in place of synthetic nonrenewable fibers. 

Conclusion

The potential applications for PHAs are numerous, and the lists included in this blog are not exhaustive. For example, applications for PHAs exist in the ‘green’ or ‘natural’ beauty and cosmetics industry. As consumers opt for natural choices and demand more transparency for cosmetic product ingredients, the use of PHAs as additives and filler in cosmetics that currently use synthetic versions have the potential to meet these needs (Coltelli et al., 2020; Kovalcik at al., 2019). PHAs also have applications in the automotive industry as biodegradable car components, such as interior trim and insulation. Additionally, their use is involved in biofuels, food grade surfactants, feed additives, biodegradable solvents, dye production, and industrial fermentation (Chen et al, 2012; Vicente et al., 2023).

In 2022, the USDA National Institute of Food and Agriculture announced a new Bioproduct Pilot Program as part of the Infrastructure Investment and Jobs Act, with the goal of “lowering commercialization risks associated with bringing bio-based products to market.” The program aims to spur economic activity with research and development on the benefits of using bio-based products that are derived from “covered agricultural commodities for [the] manufacture of construction and consumer products.” The program also supports NIFA’s goals to advance a more circular economy, “where finite resources are not just extracted and consumed but also regenerated in a sustainable manner.” Successful outcomes from such a program could potentially be transferable, help lower production costs, and support wider adoption of PHAs across industries.

Stay tuned for more on these and related topics in the future on the OliveBio blog page. 


polyhydroxyalkanoates; PHAs; agriculture; textiles; bioplastics; biomedical; industry; synthetic polymers; biodegradable polymers; renewables