Selecting Medical Materials to Withstand Sterilization: A Florence Nightingale-Inspired Upgrade

In the 1800s, Florence Nightingale, known as the founder of modern nursing, introduced a new methodology for healthcare sanitation. One of her works, “Rural Hygiene,” shared cleanliness advice that was radical at the time, including washing bedding, using unpolluted water and providing adequate ventilation in patient environments. Considered basic by modern standards, these pioneering ideas helped lay the foundation for current disinfection and medical device sterilization protocols, though the methods have advanced far beyond Florence Nightingale’s standards.

Today, medical equipment must withstand disinfection by chemicals and autoclave to get them ready for reuse and new devices often must endure steam, ethylene oxide (EtO) gas and radiation. Though healthcare professionals administer care to their patients, their success relies heavily on sterile medical devices. It is up to medical manufacturers to ensure critical tools do not fail by selecting materials that can withstand harsh disinfection methods or come ready-to-use in sterile packaging.

In recent years, the COVID-19 pandemic has reignited healthcare’s focus on cleanliness and sterilization.

“The Florence Nightingale style of maintaining a sterile field has come back in force with single-use disposables in healthcare. You make a part in a clean room environment and put it into clean packaging which is then sterilized. This process ensures that when the medical device is removed from its packaging, it is sterile and ready for use,” explained Josh Blackmore, Global Healthcare Manager, M. Holland.

But medical waste is a huge sustainability concern, so while single-use disposables are ideal for maintaining a sanitary environment, some equipment must be cleaned and sterilized for reuse instead of thrown away. This is especially true for permanent fixtures on surgical robotics machines and many orthopedics surgical tools.

“We’re upgrading our Florence Nightingale moves now, going all the way back to material selection to make sure essential healthcare equipment is clean, sterile and able to be reused,” Josh continued.

Material selection is key to creating reusable medical equipment that can withstand repeated sterilization cycles without impacting durability.

“A key consideration for medical application manufacturers should be to understand the method(s) healthcare workers will use to sanitize the device,” Josh advised. “A hospital using autoclave sterilization will require a product that doesn’t melt in extreme heat, while another facility might only have access to chemical disinfectants. It is imperative that manufacturers communicate with their customers to match materials to the intended function and avoid sterilization-related failures.”

Choosing materials based on the medical device sterilization method will ensure that critical tools don’t crack, flake, lose shape or otherwise break down after sanitization and are able to maintain the necessary level of functionality.

Hard surface disinfection employs harsh chemicals to kill microbes. Medical equipment undergoing chemical disinfection needs to withstand a range of different cleaning agents depending on government regulations and facility protocol. There are over 10 categories of chemical disinfectants. Alcohol is one of the least aggressive examples, though more extreme chemicals, such as glutaraldehyde could also be used. Sometimes multiple chemical disinfectants are used in combination. A quality medical tool will maintain its integrity no matter what chemical is used or how often it is disinfected.

For electronic housing applications subjected to chemical sterilization, Josh recommends dimensionally accurate, flame-retardant materials that can resist chemical broad-spectrum disinfection. Polycarbonate, when blended with polybutylene terephthalate, can be the perfect selection. This blend holds up to repeated chemical sterilization and can be flame-resistant-rated without compromising functionality.

Autoclave machines use a combination of steam, heat and pressure to sterilize medical devices. Applications subjected to autoclave sterilization are frequently made of high-heat-resistant materials like titanium, metal or ceramic, but plastic resins can withstand thousands of autoclave cycles as well. Most resins can withstand one autoclave cycle but could melt or deform with repeated steam cleaning. Josh noted that M. Holland rates all base resins on the number of autoclave cycles that they can withstand.

Josh recommends polyphenylsulfone for healthcare applications subject to high number of autoclave cycles because of the material’s natural heat-resistant properties. “Polyphenylsulfone has a V-0 flame rating, meaning burning stops within 10 seconds. Medical devices made with polyphenylsulfone will not deform at autoclave time and temperatures, making them safe for thousands of cycles,” Josh explained.

Gamma irradiation calls on radiation to kill bacteria. It is frequently used to disinfect plastics because gamma rays can easily pass through the material while breaking bacterial DNA bonds. Gamma irradiation does not produce heat or moisture and can be carried out safely in a controlled environment.

Medical tools that undergo gamma irradiation must not lose strength after sterilization, so they do not sacrifice performance. Acetal, for example, can become brittle or disintegrate with even one exposure to gamma radiation.

Color must be considered when materials will be subject to radiation as well. Certain materials, like polycarbonate, maintain their physical integrity but tend to turn yellow during the gamma irradiation process. Polycarbonate and other ETPs subject to this sterilization method should be stabilized against color shift or be pre-colored to mask any potential visual changes.

Though healthcare best practices have come a long way since Florence Nightingale nursed patients, sanitation remains a critical part of patient care. As medical facilities upgrade their efforts to create sterile environments, medical devices must evolve to meet new material requirements. M. Holland provides material selection guidance to healthcare manufacturers. Our team of medical plastic experts help manufacturers create products that meet local regulatory requirements and withstand daily use in healthcare facilities.

For more information, visit our Healthcare market page.