Improvements in and relating to sterilization of fluid-guiding elements for bioprocessing applications

Abstract

Disclosed is an ultraviolet (UV) light sterilizable fluid directing element (100, 200, 300, 400, 500) that can be configured to form part of a permanently closed bioprocess fluid system, at least a portion of the element formed from a material that is transparent to UV light, said at least a portion of the element including one or more surfaces (134) configured to contact and direct fluid within the closed system. The element further includes at least one UV light emitting diode (LED) (154) mounted within, on, or adjacent to at least a portion of the element and having a light output sufficient to sterilize at least the one or more surfaces (134).

Description

[Technical field]

[0001] The present invention relates generally to sterilization of flow directing elements with ultraviolet (UV) light, and more particularly to the use of such flow directing elements for bioprocessing applications. [Background technology]

[0002] As used herein, "sterile" and similar terms such as "aseptic" are intended to mean a bio-burden reduced to a level sufficient for the requirements of the intended purpose of the component, i.e., for practical purposes; sterilization of a component, as used herein, means reducing the bio-burden sufficiently for the component to perform its function without introducing undue bio-burden.

[0003] Generally, many closed fluid systems require sterile conditions to function successfully. For example, bioprocessing, medical devices, food processing, brewing, and water treatment are some examples where closed sterilization systems are used, which are pre-sterilized and kept sealed to maintain sterility.

[0004] Such systems may be cleaned prior to use with chemicals such as sodium hydroxide, ethylene oxide gas, steam, or radiation such as gamma or UV light. Of course, not all of these methods are acceptable for every closed fluid system.

[0005] However, in many instances, the opportunity to utilize other enclosed systems is required, for example, for withdrawal or partial withdrawal of a finished fluid or product, or for sampling, or for introducing fluids such as reagents or ingredients, or for monitoring of fluids using probes or sensors, where there is always a risk of introducing contaminants into the system, such as bacteria, fungi, viruses, enzymes, and similar simple forms of life, collectively referred to herein as "microorganisms."

[0006] Thus, in-process sterilization and cleaning are required in many cases, even after initial sterilization of an empty system. One particularly problematic system is cell culture in bioreactors, where a full-time closed system is maintained under conditions conducive to microbial growth and where many invasive procedures are performed during the cell culture process, such as the initial introduction of seed cells, the introduction of oxygen and cell nutrients, cell sampling, and harvesting of cells or cell products such as antibodies or other proteins.

[0007] To address potential contamination, various fittings and techniques have been proposed that purportedly maintain sterility when the system is open, but absolute sterility can never be ensured with such mechanical fittings when human activity is present, even in so-called clean room conditions.

[0008] Commercially available sterile fittings have been proposed and sold under the trade name ReadyMate®, such as those proposed in U.S. Pat. No. 6,679,529, WO2009 / 002468, and WO2013 / 147688, which provide one of the best ways to ensure sterility when connecting two different sterile fluid systems together, whereby pairs of connections, each covered by a film, are joined, and once the connections are joined, the film is removed, leaving the connections connected to each other but never exposed to their surrounding environment. Many other mechanical concepts exist that use male and female parts that are exposed after mating. Their drawback is that careful manual manipulation is required to make a viable sterile connection.

[0009] Furthermore, one major challenge with prior art system designs when used in bioprocessing applications relates to the problem of controlling microorganisms that may be trapped, for example, in the seams or stagnant areas of the bioreactor. Such systems can be difficult to keep clean during use and are required to remain sterile when in use. Any stagnant areas are therefore highly undesirable as they may trap biological material that may release pathogens or other undesirable materials into the processing batch after decomposition. Any such contamination may therefore result in the need to discard the entire batch of biopharmaceutical product. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] U.S. Patent No. 6,679,529 [Patent Document 2] WO2009 / 002468 [Patent Document 3] WO2013 / 147688 Summary of the Invention [Means for solving the problem]

[0011] The inventors of this concept recognized that even with the best sterile connections, the risk of microbial contamination is always present, and therefore a different approach is required, and that a better method is required for sterilization before, during, or after two fluid systems are connected. The inventors propose to use UV-light transparent fluid connections or other fluid-directing elements that form part of the closed fluid system, such as tubing couplers, fluid transfer ports, valves, fluid sampling interfaces, removable sensor ports, stopcocks, etc., wherever microorganisms may enter the closed fluid system from the external environment at any time, or in areas that cannot be reached by conventional pre-sterilization methods, such as joints that are too narrow to allow the passage of cleaning fluids, or stagnant areas (so-called dead legs). When exposed to UV light before and / or after they are connected to the closed system, these fluid-directing elements can transmit UV light to their fluid-contacting surfaces to sterilize the fluid-contacting surfaces and adjacent areas.

[0012] The ultraviolet (UV) light spectrum lies between 200 and 400 nanometers. The so-called UV-C part of it (wavelengths around 254 nanometers) is particularly suitable for sterilization since it has been shown that it can kill microorganisms or at least damage their DNA, thereby preventing, for example, viruses or spores from infecting cells. UV light of about 255 to 265 nanometers, for example UV light of about 260 nanometers, emitted by commercially available LEDs, is particularly suitable since it is UV=C radiation and also because very little heat is generated, i.e. such LEDs can be placed near sensitive components or liquids without risking thermal damage to them. The size of the LEDs also makes them suitable for placement in, on or near fluid guiding elements to provide localized sterilizing UV light.

[0013] It should be understood that the above summary is provided to introduce a selection of concepts further described in the detailed description below. The detailed description is not intended to identify key or essential features of the claimed subject matter, and the scope of the claimed subject matter is uniquely defined by the claims that follow the detailed description. Moreover, the claimed subject matter is not limited to implementations that solve any of the shortcomings noted above or in any part of this specification. The above advantages and other advantages and features of this specification will become readily apparent when considered in the following detailed description, either alone or in combination with the accompanying drawings. The present invention extends to any combination of the features disclosed herein, regardless of whether such combination is expressly stated herein. Moreover, when two or more features are described in combination, for example in the same paragraph, it is intended that such features may be claimed separately without broadening the scope of the invention. Features from the various embodiments described below may be combined in any claim.

[0014] The invention in its broadest form provides a fluid guide element as claimed in claim 1 having preferred features as defined by the claims dependent thereon.

[0015] The invention also provides a method as defined by claim 12.

[0016] The invention can be put into practice in various ways, illustrative, non-limiting embodiments thereof will now be described with reference to the drawings, in which: [Brief description of the drawings]

[0017] [Figure 1] FIG. 2 shows a first embodiment of a fluid guide element in the form of a pipe fitting. [Diagram 2] FIG. 2 shows a second embodiment of a fluid directing element in the form of a modified pipe joint. [Figure 3a]6A-6C show operating positions of a third embodiment of a fluid guide element; [Figure 3b] 6A-6C show operating positions of a third embodiment of a fluid guide element; [Figure 3c] 6A-6C show operating positions of a third embodiment of a fluid guide element; [Figure 4] 13A-13C show further embodiments of the fluid guide element; [Diagram 5] 13A-13C show further embodiments of the fluid guide element; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The present invention, together with its objects and advantages, may be better understood by reference to the following description taken in conjunction with the accompanying drawings in which like reference numerals identify like elements in each of the figures, and in which:

[0019] Referring to FIG. 1, a fluid directing element in the form of a fluid coupling 100 is shown. The coupling 100 includes a body 130 having a barb 132 for receiving a plastic tube 120 that is clamped on the barb by a clamp 122, and a mating face 110. The coupling 100 is intended to mate with a complementary coupling (not shown) at its mating face 110. In use, an inner surface 134 of the body 130 and the mating face 110 are in contact with a fluid. In use, the mating face 110 is presented against the complementary face and, when their respective ring seals 112 come into contact, their respective sealing films 114 are pulled together from the gap between the faces provided by the ring seal. The complementary couplings may be held together by a ring clamp (not shown) that holds their respective outer flanges 136 together. Although the system allows good assurance of maintaining the sterility of pre-sterilized couplings, the couplings, once damaged, may become contaminated and contaminate the fluid system.

[0020] In this embodiment, a sterilizing UV LED circuit 150 including a push button switch 152, a UV LED 154, a battery 156, and a current limiting resistor 158 is provided within the extension 140 of the housing 130. The LEDs provide UV sterilizing light on demand that can be internally reflected throughout the housing 130 over the area shown as hatched, and even into any gaps or tight seams that may harbor microorganisms, such as gap 138 in the exterior surface of the barb.

[0021] In use, the fluid contact surfaces 134 and 110 of the fittings can be sterilized before and / or after mating with another similar fitting. If the associated tubes 120 or equivalent parts are also made transparent, the UV light will also propagate along the tubes for at least a small distance due to internal reflection, so that they too will be partially sterilized. In a refinement, the outer surface 144 of the body 130 has UV light reflective properties, for example a polished and metal plated surface, or a surface with an internal mirror finish, to better reflect the light back to the fluid contact surface 134.

[0022] In various alternative embodiments, a remotely controllable, contactlessly powered, and / or transistor switch actuated UV LED circuit may be provided. Such UV LED circuitry may be provided for multiple bioprocessing system components and operated collectively, for example, by a remote computer system. This may thus enable the provision of an automated bioprocessing system that may be operated in a coordinated manner to enhance sterilization efficiency.

[0023] 2 shows another fluid directing element 200 in the form of a fluid coupling similar to coupling 100, with similar parts having the same last two digits. In this embodiment, the fluid contact surfaces 234 and 210 are sterilized in use by the light internally reflected from the UV LED circuit 250 as before, as described above. In this case, the extension 240 housing the LED circuit 250 also includes a shroud 242 that fits snugly over the body 230 and has a highly reflective surface 244, such as a polished metal or electroplated metallized finish, on the surface adjacent to the body 230, except for the area 256 adjacent to the LEDs 254 to allow light to enter the transparent body 230. This configuration is more efficient than the embodiment of FIG. 1, since more LED light is recycled by the reflective surface, and can also be retrofitted into existing couplings that do not have provisions for an LED circuit. As an alternative, the body 230 can be highly reflective with a window similar to the window 256, e.g., a mirrored outer surface, instead of a reflective shroud 242, in which case the shroud 242 functions only as a removable mount for the UV circuit 250 including the adjacent LED light source 254.

[0024] 3a shows another fluid directing element 300 in the form of a fluid tube 320 and a two-part tube clamp 330 / 340. Here, the outer tube clamp 340 is intended to house an LED circuit 350 to provide sterilizing light to the inner tube clamp 330. If the tube 320 is also transparent to UV light, the propagation of UV light through the inner tube clamp 330 will sterilize, by internal reflection, the inner surface 334 of the tube 320 and the tube joint 338 between the tube 320 and its insert 30 that fits inside the tube 320.

[0025] 3b and 3c, it can be seen that in use, the inner clamp 330 is slid axially over the plug 30 and then the outer clamp 340 is slid axially over the inner clamp 330, clamping the inner clamp 330 around the tube 320 to hold the tube 320 in place on the plug 30. During the clamping process, the UV LEDs may be illuminated for a period of time and to provide some relative movement of the LEDs to provide complete sterilization of the fitting 300.

[0026] 4 shows a fluid directing element in the form of a port 400 suitable for accessing a bioprocess container 40, for example, for supplying fluid, withdrawing fluid, taking a sample, or inserting a probe or sensor into the container. When not in use, the port is sealed, for example, using a screw cap (not shown). The port 400 includes a body 430 that is transparent to UV light and has a fluid access opening 420, and a body extension 440 that houses a UV LED circuit 450. The body is transparent and allows UV light to propagate to the fluid contact surface 434 of the opening 420 before, during, and / or after use of the port. In this case, the port may be used adjacent to cells or other biomaterial, and therefore the wall 42 of the container 40 is made from a UV LED non-transparent plastic to prevent damage to the contents of the container from stray UV light.

[0027] 5 shows a fluid directing element in the form of a ball valve 500 with a valve body 530 housing a UV LED circuit 550 including multiple LEDs. The body 530 is transparent to UV light and includes a fluid passageway 520 and a rotating valve mechanism 538, each of which may be sterilized by allowing light to propagate by internal reflection around the body to the passageway 520 and to the valve seam between the body 530 and the mechanism 538. The various passageways of the valve, and any seams or dead legs, may thereby be sterilized before and after use of the valve. Alternative valve devices may also be sterilized in this manner.

[0028] It will become apparent that other configurations similar to those described above may be used to enable the fluid directing element to be sterilized by UV light for subsequent use in a normally sealed fluid system.

[0029] Sterilization can be achieved using weakly UV-transparent materials, i.e. materials that do not transmit light particularly well, or materials that absorb UV light, but effective sterilization can be assured if at least 5% of UV light is transmitted per mm of element thickness (5% / mm).

[0030] There are many materials that are useful for transmitting UV light, for example glass, e.g. quartz glass. However, for disposable products typically used in bioprocessing and medical applications, plastics would be more economical. In this regard, it is also typical to gamma pre-sterilise plastic components before use, in which case some plastics will lose their UV light transmission properties. Suitable plastics are polypropylene (PP), polymethylmethacrylate (PMMA), polydimethylsiloxane (PDMS), polyimide (PI), although polypropylene (PP) suffers from UV degradation over time, polymethylmethacrylate (PMMA) is not particularly UV-transparent for light with wavelengths shorter than 250 nm, but its transmission properties are acceptable for wavelengths around 260 nm, i.e. about 50% / mm, polydimethylsiloxane (PDMS) is not easily injection moldable, and polyimide (PI), e.g. fluorinated PI, is stable and transmits all UV light when made colourless.

[0031] If less transparent materials are used or faster sterilization is required, more than one LED may be used, for example a ring of LEDs may be used in any of the above embodiments.

[0032] Although exemplary embodiments have been described and illustrated, it will be apparent to the skilled addressee that additions, deletions, and modifications can be made to those embodiments without departing from the scope of the invention as claimed. For example, circuits 150, 250, 350, 450, and 550 are intended to have a local power supply, for example, by a battery, for convenience. The configuration is compatible with disposable type fluid directing elements, such as disposable fluid couplings, but if reusable elements are required, a remote power source, for example, a plug-in dc supply, can be used. Although only the embodiment of FIG. 1 has been described as optionally including a back-reflective exterior surface, other embodiments can also include such a surface. [Explanation of symbols]

[0033] 30 Insertion part 40 Bioprocess Container 42 Wall 100 Fluid Coupling 110 Mating surface, fluid contact surface 112 Ring Seal 114 Sealing film 120 Plastic Pipe 122 Clamp 130 Body, housing 132 Barb 134 Internal surfaces, fluid contact surfaces 136 Outer flange 138 void 140 Extension 144 Outer surface 150 Sterile UV LED Circuit 152 Push button switch 154 UV LED 156 Batteries 158 Current limiting resistor 200 Fluid Guiding Elements 210 Fluid contact surfaces 230 Body 234 Fluid contact surfaces 240 Extension 242 Shroud 244 Highly reflective surface 250 UV LED circuit, UV circuit 254 LED, LED light source 256 regions, windows 300 Fluid guide elements, joints 320 Fluid pipe 330 2-piece tube clamp, inner tube clamp, inner clamp 334 Inner surface 338 Pipe Joint 340 2-piece tube clamp, outer tube clamp, outer clamp 350 LED circuit 400 Port 420 Fluid Access Opening 430 Body 434 Fluid contact surfaces 440 Main body extension 450 UV LED circuit 500 Ball Valve 520 Fluid passage 530 Valve body 538 Rotary valve mechanism 550 UV LED circuit

Claims

1. 1. An ultraviolet (UV) light sterilizable fluid directing element (100, 200, 300, 400, 500) for bioprocessing applications, configurable to form part of a permanently closed fluid system, wherein at least a portion of the element is formed from a material that is transparent to UV light, wherein the at least a portion of the element comprises one or more surfaces (134) configured to contact and direct a fluid in the closed system in use, wherein the element further comprises at least one UV light emitting diode (LED) (154) mounted in, on or adjacent to the at least a portion and having a light output sufficient to sterilize at least the one or more surfaces (134), wherein the material is a plastic material that is sterilizable with gamma radiation, and wherein the material is polyimide (PI).

2. The fluid directing element (100, 200, 300, 400, 500) of claim 1, wherein the LED (154) emits light with a wavelength between 100 nanometers and 280 nanometers.

3. 3. The fluid guide element (100, 200, 300, 400, 500) according to claim 1 or 2, wherein the material transmits more than 5% of the UV light per mm of light propagation distance.

4. The fluid directing element (100, 200, 300, 400, 500) according to any one of the preceding claims, wherein the material is a fluorinated polyimide.

5. The fluid directing element (100, 200, 300, 400, 500) according to any one of claims 1 to 4, being one or more of a fluid connector, a tube coupler, a removable fluid transfer port, a valve, a fluid sampling interface, a removable sensor port, a stopcock, or an element at a point where microorganisms can enter the permanently closed fluid system from the external environment.

6. 6. A fluid guide element (100, 200, 300, 400, 500) according to any one of claims 1 to 5, wherein the element comprises a body (130) having the one or more surfaces configured to contact and guide a fluid, the body (130) supporting a circuit (150, 250) for operating the at least one LED (154).

7. The fluid directing element (100, 200, 300, 400, 500) of claim 6, wherein the circuit (150, 250) comprises a push button switch (152), a UV LED (154), a battery (156), and a current limiting resistor (158).

8. 8. The fluid directing element (100, 200, 300, 400, 500) according to claim 6 or 7, wherein the outer surface of the body (130) comprises highly reflective areas for reflecting UV light, the outer surface of the body being not in contact with the fluid.

9. The fluid guide element (100, 200, 300, 400, 500) according to any one of claims 6 to 8, wherein the body includes a shroud (242) for supporting the circuit (250), the shroud optionally having a reflective surface (244) adjacent the body (130) for reflecting UV light.

10. The fluid directing element (100, 200, 300, 400, 500) according to any one of the preceding claims, comprising a body (130) or a housing configured to reflect UV light into at least one cavity (138) capable of hosting microorganisms.

11. 1. A method for maintaining sterility in a normally sealed fluid system for bioprocessing applications, comprising: a) opening said fluid system at a fluid directing element (100, 200, 300, 400, 500) at least a part of which is in contact with the fluid; b) closing the fluid system at the element; c) sterilizing said portion of said element by UV light transmitted by propagation within said element to said portion in fluid contact before and / or during and / or after closure; Including, A method, wherein at least a portion of said element is formed from a gamma sterilizable plastic material, said gamma sterilizable plastic material being polyimide (PI).

12. The method of claim 11 , wherein the UV light is from an LED (154) having an output wavelength of 100 nanometers to 280 nanometers.

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