DE102009029792A1 - Container useful as component of photobioreactors for storing or transferring aqueous solutions or suspensions, where inner wall of the container is provided with coating, which prevents adhesion of biologically reproducible substances - Google Patents

Abstract

The container useful as a component of photobioreactors for storing or transferring aqueous solutions or suspensions, is claimed, where an inner wall of the container is provided with a coating, which prevents the adhesion of biologically reproducible substances such as algae compared to a similar uncoated container. The container and the coating are partially transparent in a spectral region. The coating reduces the adhesion of the biologically reproducible substances around 95% in comparison to the uncoated surfaces. The container contains glass, glass ceramic and/or plastic. The container useful as a component of photobioreactors for storing or transferring aqueous solutions or suspensions, is claimed, where an inner wall of the container is provided with a coating, which prevents the adhesion of biologically reproducible substances such as algae compared to a similar uncoated container. The container and the coating are partially transparent in a spectral region. The coating reduces the adhesion of the biologically reproducible substances around 95% in comparison to the uncoated surfaces. The container contains glass, glass ceramic, plastic and/or glass or plastic composite material. The coating has a layer thickness of 5-20 nm and is transparent in the spectral region required for the biological reproduction and/or for maintenance of the viability of the biologically reproducible substances. The coating in the spectral region has a transparency of larger than 90%, exhibits a protein-resistant effect, comprises a hydrogel, and is produced by a plasma-impulse chemical vapor deposition process and/or a plasma-enhanced chemical vapor deposition process. The pulse energy of the coating process is maximum 3 Joule. The coating is temperature-stable at 121[deg] C compared to steam sterilization, is produced by a sol-gel process, and is produced with common coating process by sputtering, by wet chemical using sol-gel-process or an immersing process. The contact angle of the coating to diethyl ether and water is 0.5-10[deg] . An independent claim is included for a method for operating a photobioreactor.

Description

The This invention relates generally to coatings for containers water-bearing systems, in particular coatings for Photobioreactors showing an attachment of organisms to the walls reduce the container.

description

One fundamental problem of aquatic systems and in particular of photobioreactors is that with increasing Operating time on the walls of containers a biofilm formed. Biofilms are predominantly formed in aqueous Systems, both at the surface of the liquid as well as at interfaces to a solid phase. It deals This is usually a thin layer of mucus, the Microorganisms such as algae, bacteria, fungi or Contains protozoa. These microorganisms contaminate usually the water and can - in special Cases - to a very considerable extent Reduce the volume of the containers.

In Reference to photobioreactors used for the cultivation of phototrophic or photosynthetic organisms, often microorganisms such as algae are used, additional Disadvantages of such biofilms. Centerpiece of the photobioreactors are transparent containers in which microorganisms in be grown a liquid culture medium. A biofilm attached to the walls of a photobioreactor forms, reduces the entry of light into the system, wherein Light a limiting factor for growth and / or the proliferation of photosynthetic or phototrophic organisms is. In addition, lead to extensive deposits of microorganisms on the walls of photobioreactors too to a reduction in the yield, since they are the volume of the reactor Reduce. In particular, the bacteria affect in the biofilm, the growth of algae through contamination of the nutrient solution with their excretions.

Out The prior art are different approaches to Elimination or prevention of biofilms at interfaces known. From the ship area, for example, are paintings or Also known coatings, in different ways the Training of biofilms and subsequent colonization to prevent with macroorganisms. Very widespread toxic substances or self-eroding materials, which and delivered to the environment. Toxic substances, such as copper or silver-containing coatings from which leached out high concentrations of Cu or Ag cations are, however, in view of the propagation to be achieved of the organisms for use in photobioreactors generally not suitable. In addition, must Coatings for photobioreactors translucent or transparent, which is the case with many of the aforementioned coatings not the case.

To avoid biofilms, especially in photobioreactors, mechanical cleaning methods are known which are based on regular "wiping" of the biofilm by means of different methods. The EP 1 011 880 B1 describes, for example, the use of granules or grains for the mechanical removal of biofilms. In the exemplary embodiments, glass beads are named which will enter the reactor together with a culture medium. By pumping the culture medium and the glass beads contained therein, the reactor walls are kept clean by mechanical abrasion. However, this method has the disadvantage that on the one hand the microorganisms to be cultivated can be mechanically damaged and on the other hand the reactor walls are subject to constant abrasion. The abrasion of the reactor walls is on the one hand damaging to the material used and on the other hand also leads to the entry of abrasive material in the culture medium with the organisms to be cultivated. Abrasion on the reactor walls leads to turbidity of the reactor wall and thus to a reduced transmission. However, a lower light input reduces the desired algae cultivation inside the photobioreactor. Depending on the use of the cultured organisms, such an entry may constitute undesirable contamination of the final product. Furthermore, abrasive additional body of glass or plastic means additional operating costs and thus costs.

About that In addition, the organisms to be propagated, for example Algae, respond to the permanent movement with stress. Some Algae species develop, for example, triggered by mechanical Movement a special "stickiness", d. H. the Colonization of the surface caused by mechanical abrasion or to be reduced by movement of the culture medium is strengthened.

The The object of the invention is therefore an optionally transparent To provide reservoirs for aquiferous systems, in which the attachment of biofilms is comparatively low. In particular, based on photobioreactors, the addition of Biofilms be low without the growth and proliferation of the organisms to be produced to impair. Due to less necessary downtime to clean the container should be a more effective use the water-bearing system can be achieved.

These Task is done in an amazingly simple way already by the independent Claims solved. Advantageous developments The invention are defined in the subclaims.

According to the invention a container for storage or forwarding of aqueous Solutions or suspensions, in particular for photobioreactors, provided, wherein the container inner wall with a coating which is opposite to a similar uncoated Container the adhesion of biologically augmentable substances, in particular algae, diminished, and wherein the container and the coating at least in a spectral range at least are partially transparent. A reduction in the adhesion of biological extensible substances, the expert can, for example by gravimetric comparative studies or by means of comparative transmission measurements prove.

photobioreactors are often used to propagate or breed microorganisms, The organisms to be propagated are often also part of the disturbing Biofilms are.

The invention is expressly not limited to particular types or embodiments of photobioreactors; exemplified on the in the writings EP 1 632 562 B1 . EP 1 169 428 B1 and EP 0 506 568 B1 referenced types of photobioreactors.

Especially advantageous is that the coating as such for the colonization by microorganisms is not suitable. This can be on mechanical methods of reducing biofilms that are negative can affect the organically growing organisms be waived.

The Designation "biologically reproducible" describes in the context of this invention, the increase of the biologically utilizable Material and includes in particular cell division, the growth of Cell or other effects that increase the number and / or the weight of the respective cells or biological material cause.

To a development of the invention is under a reduced Attachment of biologically augmentable substances understood that the Kinetics of growth in an inventive Photobioreactor by at least 50%, preferably by at least 90% and more preferably at least 95% over an uncoated one Photobioreactor is reduced.

Of the Containers for storage or forwarding of aqueous Solutions or suspensions according to the invention in no way to a particular shape or volume limited and may be glass, glass ceramic, plastic and / or Plastic composites include. Preference is given to borosilicate glass, Aluminum silicate glass, soda lime glass, polymethyl methacrylate or Contain cycloolefin copolymers. When cultured phototrophic organisms should be chosen, the material is preferably to be selected that its transmission to the wavelength range preferred by the organisms is tuned.

Also the coating of the wall of the container should at least in the necessary for the organisms to be multiplied wavelength or Spectral range to be transparent or at least partially transparent. The organisms, such as algae, certainly different demands on the lighting conditions during the propagation and maintenance of their Have viability or life activity.

According to one preferred embodiment of the invention, the container Be part of a photobioreactor. The shape and the texture the coated container is not relevant. For example, it can be tubular or tubular, tubular or bag-shaped Photobioreactors to flat plate photobioreactors or glass tank photobioreactors act.

According to a development of the invention is the layer thickness of the coating the container advantageously between 2 and 300 nm, preferably between 2 and 200 nm, and more preferably between 5 and 20 nm.

A Particularly preferred embodiment of the invention provides that the coating has a protein-repellent effect. protein-repellent means for the purposes of this description and claims, that attachments of proteins to the coated surface less than buildup on the uncoated surface are. This may apply for a period of weeks or months or more permanent. This statement can be for pouring Systems and / or for static, non-flowing Systems apply.

The Surprisingly, inventors have found that protein repellent Coatings Particularly effective in reducing algae growth. tries have shown that the upgrowth on with protein repellent coatings provided substrates by more than 95% compared to uncoated Surfaces can be reduced (see embodiment Chlorella elution after 14 days) According to one particular preferred embodiment of the invention comprises the protein-repellent coating a hydrogel.

According to one embodiment of the invention, the coating is applied to the inside or even only on portions of the inside of the container by a CVD method, particularly preferably by plasma impulse chemical vapor deposition (PICVD method). A description of the PICVD method can be found in the document EP 1 810 758 A1 ,

In a further embodiment, the coating can also take place by means of a plasma enhanced chemical vapor deposition (PECVD process), for which a typically used reactor in a publication of L. Cao, B. Ratner and T. Horbett (J.M. of Biomedical Materials Research Part A DOI 10.1002 / jbm.a, Figure 2 ) is shown.

alternative The PA layer can also be produced by liquid coating become.

Around To ensure a good use of light, the coating should be the container of a photobioreactor a transparency of greater than 90% in the desired wavelength range exhibit. As for many organisms and especially algae the visual spectral range is decisive, is also here one Transparency of the coating greater than 90% prefers.

About that In addition, the coating is preferably temperature stable up to 270 ° C, particularly preferably stable up to at least 121 ° C., to allow steam sterilization.

The following chemical families are preferred as precursors: glycols, ethers, Esters, alcohols, methacrylates, silanes and their respective derivatives.

According to one Development of the invention comprises a protein-repellent coating the container at least one polyalkylene glycol and / or at least a polyalkylene glycol derivative.

Prefers the coating comprises at least one polyalkylene glycol from the Group ethylene glycol, diethylene glycol, triethylene glycol and tetraethylene glycol.

In a particular embodiment of the invention comprises a protein-repellent Coating the photobioreactor a mono- or dialkyl ether at least a polyalkylene glycol, with mono- or dimethyl ether being preferred are, in particular the tetraethylene glycol dimethyl ether.

The Tetraethylene glycol dimethyl ether coating according to the invention has a contact angle of approx. 50-60 ° for water.

The Hydrophilicity of the coatings or their contact angle for Water has a strong dependence on the on the coating process used pulse energy. Layers, which were deposited with lower energies are comparatively hydrophilic and more protein repellent.

It is therefore preferred to have a low pulse energy for the production of according to the invention coated container use; In particular, a pulse energy of 3 joules is not exceeded.

A further embodiment of the invention is characterized in that that the coating of the container or the photobioreactor a modified by a graft reaction polyalkylene glycol and / or such a modified polyalkylene glycol derivative.

A particular embodiment of the invention provides a hydrophilic Coating the container before, the contact angle to Water is less than 20 ° and preferably between 0.5 ° and 10 °. Such a layer preferably comprises titanium dioxide, which has a photocatalytic effect under illumination and hydrophilic is. These layers can be processed using the common coating methods be applied, preferably by sputtering and more preferably wet-chemically as sol-gel layers, in particular in the dipping process.

About that In addition, the invention includes a method for operating a photobioreactor, wherein at least one coated section of a erfingungsgemäßen Container for breeding of biologically reproducible Material is used. The biologically reproducible material, in particular Algae, is grown or propagated under the influence of light, the adhesion of this material to the coated container inner wall compared to a similar uncoated container is reduced.

The Invention will be described below with reference to embodiments and with reference to the accompanying drawings explained.

A The scope of protection is limited by the mentioned embodiments explicitly Not.

It demonstrate:

1 a diagram of the growth with Chlorella algae,

2 a diagram of fouling with Glaphyrella algae,

1 Represents the chlorella-algae growth on different substrates after 14 days of storage in the algal suspension.

Of the Error bar shows the variation of several measured substrates at.

The Algae density on the coated Fiolax glass is an upper limit because the algae were not fully attached.

2 shows the Glaphyrella algae growth on different substrates after 9 days storage in the respective algal suspension.

Experimental procedure:

to Investigation of algae-growth-inhibiting effects were made with protein-repellent Coated or uncoated glass shards in Erlenmeyer flasks in which previously algae suspensions had been bred were.

After storage for 9 days or 14 days in room temperature of the test glasses in the unstirred algae suspension, it was determined by counting under the microscope and extrapolation how many algae adhere to a glass surface of 1 cm ² .

The protein-repellent coating, consisting of a polyethylene glycol / tetraethylene glycol dimethyl ether mixture, was applied by means of a PICVD process, which is described in the document EP 1 810 758 A1 (paragraph [0033]); while the came in 1a the aforementioned font PICVD reactor used.

Examines were shards of coated or uncoated pharmaceutical vials made of Fiolax glass (contact angle 51-57 °) and of uncoated tubes made of Duran glass (contact angle 14-23 °), wherein the protein repellent layer had a thickness of about 45 nm.

• a) Chlorella vulgaris (SAG 211–11b), die industriell am häufigsten kultivierte Algenart mit durchschnittlicher Neigung zur Anhaftung.
• b) Glaphyrella luteoviridis (ROS 77/1), eine in der Natur ausschließlich in Biofilmen vorkommende und außerordentlich klebrige Algenart.

As algae types were used:

• a) Chlorella vulgaris (SAG 211-11b), the most commonly cultivated species of algae with an average tendency to adhere.
• b) Glaphyrella luteoviridis (ROS 77/1), a species of algae exclusively found in biofilms and extremely sticky in nature.

• 1. Die proteinabweisende (PA-)Schicht behinderte nicht das Algenwachstum in der Lösung; die Beschichtung vergiftete demnach nicht die Algensuspensionen
• 2. Auf der proteinabweisenden Schicht hafteten nach 14 Tagen deutlich weniger Chlorella-Algen als auf den Referenzsubstraten: Die Algenanhaftungen auf unbeschichtetem Duran-Glas betrugen ca. 0.48·10⁶ cm^–2, auf unbeschichtetem Fiolax-Glas ca. 1.2·10⁶ cm^–2 und auf der proteinabweisenden Schicht unter ca. 0.03·10⁶ cm^–2 (1).
• 3. Auf der proteinabweisenden Schicht hafteten nach 9 Tagen deutlich weniger Glaphyrella-Algen als auf den Referenzsusbstraten: Die Algenanhaftungen auf unbeschichtetem Duran-Glas betrugen ca. 0.16·10⁶ cm^–2 und auf der proteinabweisenden Schicht ca. 0.025·10⁶ cm^–2 (2).

The results obtained after storage in the algal suspensions can be summarized as follows:

• 1. The protein repellent (PA) layer did not hinder algae growth in the solution; the coating therefore did not poison the algae suspensions
• 2. Clearly less chlorella algae adhered to the protein-repellent layer after 14 days than on the reference substrates: the algae adhesions on uncoated Duran glass were about 0.48 × 10 ⁶ cm ^-2 , on uncoated Fiolax glass about 1.2 × 10 ⁶ cm ^-2 and on the protein-repellent layer below about 0.03 × 10 ⁶ cm ^-2 ( 1 ).
• 3. On the protein-repellent layer, significantly fewer Glaphyrella algae adhered after 9 days than on the reference substrate strips. The algae adhesions on uncoated Duran glass were about 0.16 × 10 ⁶ cm ^-2 and on the protein-repellent layer about 0.025 × 10 ⁶ cm ^{. 2} ( 2 ).

All in all the protein-repellent layer shows a significantly lower algae coverage as the glass surfaces of the uncoated glasses.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 1011880 B1 [0005]
• - EP 1632562 B1 [0011]
• - EP 1169428 B1 [0011]
• EP 0506568 B1 [0011]
• - EP 1810758 A1 [0021, 0047]

Cited non-patent literature

• - L. Cao, B. Ratner and T. Horbett (J. of Biomedical Materials Research Part A DOI 10.1002 / jbm.a, Figure 2 [0022]
• -) [0022]

Claims (24)

Container for storage or forwarding of aqueous solutions or suspensions, in particular Photobioreaktoren, wherein the container inner wall with a Coating is provided, which compared to a similar uncoated containers the adhesion of biologically reproducible Substances, especially algae, diminished, and wherein the container and the coating at least in a spectral range at least are partially transparent. Container according to claim 1, characterized that the coating adheres to the biologically reproducible Substances, in particular of algae, compared to uncoated Surfaces at least 50%, preferably at least 90% and especially preferably reduced by at least 95%. Container according to claim 1 or 2, characterized characterized in that the container comprises materials Glass, glass ceramic, plastic and / or glass or plastic composite materials, preferably borosilicate glass, aluminum silicate glass, soda-lime glass, Contains polymethyl methacrylate or cycloolefin copolymers. Container according to one of the preceding claims, characterized in that the coating has a layer thickness between 2 and 300 nm, preferably between 2 and 200 nm and in particular preferably between 5 and 20 nm. Container according to one of the preceding claims, characterized in that the coating at least in one for biological propagation and / or maintenance the viability of biologically augmentable substances, especially of algae, necessary spectral range transparent is. Container according to one of the preceding claims, characterized in that the coating in the visual spectral range has a transparency greater than 90%. Container according to one of the preceding claims, characterized in that the coating is protein repellent Effect shows. Container according to claim 7, characterized the coating comprises a hydrogel. Container according to one of the preceding claims, characterized in that the coating is formed by a CVD process, preferably by a PICVD method and / or a PECVD method can be produced. Container according to claim 9, characterized that the pulse energy of the coating process a maximum of 3 joules is. Container according to one of the preceding claims, characterized in that the coating is up to 270 ° C is temperature stable. Container according to one of the preceding claims, characterized in that the coating is stable over Steam sterilization, especially stable against one Steam sterilization at 121 ° C is. Container according to one of the preceding claims, characterized in that the coating comprises at least one polyalkylene glycol and / or at least one polyalkylene glycol derivative. Container according to one of the preceding claims, characterized in that the coating comprises at least one polyalkylene glycol from the group ethylene glycol, diethylene glycol, triethylene glycol and tetraethylene glycol. Container according to one of the preceding claims, characterized in that the coating comprises at least one polyalkylene glycol derivative, in particular a mono- or dialkyl ether, preferably a mono- or dimethyl ether, includes. Container according to one of the preceding claims, characterized in that the coating comprises at least one polyalkylene glycol derivative, in particular a tetraethylene glycol dimethyl ether ("tetraglyme") includes. Container according to one of the preceding claims, characterized in that the coating is a by a grafting reaction modified polyalkylene glycol and / or polyalkylene glycol derivative includes. Container according to one of the preceding claims, characterized in that the coating by means of a sol-gel process can be produced. Container according to one of the preceding claims, characterized in that the contact angle of the coating to diethyl ether is less than 20 ° and preferably between 0.5 ° and 10 °. Container according to one of the preceding claims, characterized in that the contact angle of the coating is less than 20 ° to water and preferably between 0.5 ° and 10 °. Container according to claim 20, characterized the coating comprises titanium dioxide. Container according to claim 20 or 21, characterized that the coating with common coating methods can be produced, preferably by sputtering or wet-chemical means a sol-gel process or by a dipping process. Use of a container according to one of the preceding Claims as a component of a photobioreactor. Method for operating a photobioreactor, comprising using at least one coated portion A container according to any one of the preceding claims for the breeding of biologically reproducible material, in particular of algae, under irradiation of light, the adhesion of the biologically reproducible material to the coated container inner wall compared to a similar uncoated container is reduced.