FIBERS WITH SEGMENTS, THEIR PREPARATION AND APPLICATIONS THEREOF

Abstract

The present application discloses a method to produce fibers with different segments along the major axis. The different segments can be constituted of the same materials that entrap different objects (molecules, particles) or can be made of different materials. The different segments are made thanks to a junction and by alternating the dispensing of such materials using different inlet channels. This method allows the production of fibers that can be used as processed or after being further manipulated by other processes, as single devices or as building blocks to construct devices that are more complex. Fibers with different segments along the axis can be exploited for a wide range of applications as medical devices and/or as drug delivery system and/or as matrices to be used for acellular tissue regeneration and cellular tissue engineering/regenerative medicine strategies and/or as supports for imaging in high throughput screening.

Claims

1. An extruded segmented polymeric fiber comprising: a plurality of different segments along a major axis of the polymeric fiber, including at least: a first polymeric segment, and a second polymeric segment, wherein the first and second polymeric segments each comprise polymeric material; wherein the polymeric material of the first polymeric segment is different from the polymeric material of the second polymeric segment or, wherein the first polymeric segment and the second polymeric segment comprise the same polymeric material with a different component, wherein said component is at least one of following elements: molecules, drugs, therapeutic agent, bioactive factors, growth factors, cells, particles, small parts of living tissues or a combination thereof.

2. The fiber according to claim 1, wherein the first and the second polymeric segments are connected.

3. The fiber according to claim 1, wherein the polymeric material is a hydrogel.

4. The fiber according to claim 1, wherein the first and second polymeric segments have different lengths and wherein the different length of each of the first and second polymeric segments is obtainable by applying different pressures.

5. The fiber according to claim 1, wherein the polymeric material of the first and second polymeric segments is selected from the group consisting of: polymeric precursor, anionic polymer, and thermoresponsive polymer.

6. The fiber according to claim 1, wherein the polymeric material of the first and second polymeric segments is selected from the group consisting of: gellan gum, alginate, collagen, gelatin, and carrageenan.

7. The fiber according to claim 1, wherein at least one polymeric segment comprises a concentration gradient of said component.

8. The fiber according to claim 6, wherein the gellan gum is a methacrylated gellan gum or a acrylated gellan.

9. The fiber according to claim 6, wherein the gelatin is a methacrylated gelatin or a acrylated gelatin.

10. The fiber according to claim 1, wherein the first polymeric segment comprises alginate and the second polymeric segment comprises gellan gum, or the first polymeric segment comprises gelatin and the second polymeric segment comprises collagen.

11. The fiber according to claim 1, wherein the fiber is 400 m in diameter.

12. The fiber according to claim 1, wherein the polymeric segments vary in width and length.

13. (canceled)

14. (canceled)

15. (canceled)

16. (canceled)

17. A method for treating a patient using a patch comprising the extruded segmented polymeric fiber of claim 1 for wound healing.

18. A method of producing an extruded segmented polymeric fiber comprising different segments along the major axis, comprising: preparing a first reservoir of a first polymeric solution; preparing a second reservoir of a second polymeric solution; connecting the first reservoir to a first inlet channel; connecting the second reservoir to a second inlet channel; connecting the first inlet channel and the second inlet channel to a junction; connecting an outlet channel to the junction; applying pressure to the first reservoir to push the first polymeric solution through the first inlet channel towards the junction; applying pressure to the first reservoir to push the first polymeric solution and extrude the first polymeric solution into the outlet channel; reducing the pressure of the first reservoir to push the first polymeric solution through the first inlet channel towards the junction, maintain the first polymeric solution at an edge of the junction; applying pressure to the second reservoir to push the second polymeric solution through the second inlet channel towards the junction; applying pressure to the second reservoir to push the second polymeric solution and extrude the second polymeric solution into the outlet channel; reducing the pressure of the second reservoir to push the second polymeric solution through the second inlet channel towards the junction, maintain the second polymeric solution at the edge of the junction; alternating the pressure applied to the first reservoir and the second reservoir to alternate the polymeric solution being extruded into the outlet channel; stopping the pressure applied to the first reservoir and the second reservoir when the desired length of extruded fiber has been achieved.

19. The method according to claim 18, further comprising hardening the extruded fiber inside the outlet channel or outside the outlet channel.

20. The method according to claim 19, wherein the hardening of the extruded polymeric fiber is done by: temperature variation, chemical cross-linking, contact with a salt solution, irradiation by ultraviolet light in the presence of a suitable photo-initiator, or electromagnetic stimuli.

21. The method according to claim 18, wherein the inlet and outlet channels are connected to at least one flow sensor to measure the flow of the polymeric solutions.

22. The method according to claim 18, wherein the size of the channels ranges between 10 m and 5 mm.

23. The method according to claim 18, wherein the pressure applied to the reservoirs is equal to or higher than 1000 Pa.

24. The method according to claim 18, wherein the pressure of one of the reservoirs range from 0.1% to 5% of the pressure of the other reservoir.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The features of the present technology are explained in detail in the appended claims. The invention itself may be best understood by reference to the following detailed description that describes exemplary embodiments of the present technology. Without intent to limit the disclosure herein, the invention, its benefits, and advantages may be best understood by reference to the accompanying drawings.

[0050] FIGS. 1A-1B: Show schematics of the apparatus needed for the current invention. The apparatus itself is not claimed by this invention but only the process to make fibers with different segments.

[0051] FIGS. 2A-2C: Show schematics and simplified representations of the process. Two channel (called inlet 1 and inlet 2) join through a junction to a common outlet channel. By applying pressure, a fluid flows into the inlet channel. By selectively and alternatively applying pressure to the inlet channels different segments are formed, one made of solution 1 (coming from channel 1) and one made of solution 2 (coming from channel 2).

[0052] FIGS. 3A-3B: Show schemes showing the outcome of the process and the definition of the following terms Major axis of fiber, width of segment, length of segment.

[0053] FIG. 4: Shows a flow chart of the operational procedure to make the fiber.

[0054] FIG. 5: Shows fibers made of two components (black and white) where the black component has an increasing size.

[0055] FIG. 6: Shows fibers made with the same method of FIG. 5 but this time the white component has an increasing size while the black component is constant.

[0056] FIG. 7: Shows fibers made of three components, White (W), Blue (B), and Red (R).

[0057] FIG. 8: Shows a continuous fiber with polylactic acid particles entrapped in some segments.

[0058] FIG. 9: Shows the segments containing the particles of FIG. 8 release from the rest of the fiber.

[0059] FIG. 10: Shows a segment of the fiber containing living cells.

[0060] FIG. 11: Shows a scheme to produce a patch for wound healing applications as an example.

[0061] FIGS. 12A-12C: Show some of the steps to produce a 2 components patch.

[0062] FIGS. 13A-13C: Show three different patches of different sizes and number of components.

[0063] FIG. 14: Shows a fiber with segments of different length containing living cells.

[0064] FIG. 15: Shows a fiber with segments comprised of a gradient of different cells compositions.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0065] Reference will now be made to the attached figures to describe the present invention. The detailed description and technical contents of the present application will be disclosed herein according to a preferable embodiment. The embodiments are not used to limit its execution scope.

[0066] In one embodiment, two inlet channels are used in the production of the fibers (FIG. 1A). However, more channels can be used and the scheme can be modified accordingly (e.g. in FIG. 1B, where 1, 2 and 3 are inlet).

[0067] In another embodiment, there is a reservoir for each channel (FIG. 1A), the reservoir contains a fluid. The fluid is a solution of a polymeric precursor that can harden and forms a solid. The reservoir is connected to a source of pressure and to the inlet channel. When pressure is applied to the reservoir, the fluid in the reservoir flows into the channel up to a junction. The junction is such that the fluids coming from the different reservoirs are connected. FIG. 1A shows the junction for two inlet channels while FIG. 1B shows the junction for three inlets. In another embodiment the apparatus contains a flow sensor able to measure the flow of the fluids inside the channels and control the flow rate of the fluid by a feedback system to the pressure source. Furthermore, the flow sensor is placed along one or more channels in any place suitable for the application.

[0068] FIGS. 2A-2C show one way of carrying out the invention using two inlet channels.

[0069] In one embodiment, pressure is applied to both reservoirs so that the fluids flow into the inlet channel up to the junction point (FIG. 2A). At this point, the pressure on both reservoirs is stopped. Pressure is then applied to only one of the reservoirs (e.g FIG. 1AReservoir 1) so that the fluid contained (Fluid 1) flows into the outlet channel (FIG. 2B). For this purpose, a minimal pressure is applied to reservoir 2 (e.g. FIG. 1A Reservoir 2) to keep the flow rate of fluid 2 at 0 and avoid re-fluxes into Inlet Channel 2. This pressure ranges from 0.1 to 5% of the pressure on reservoir 1. Then, pressure on Reservoir 1 is stopped (and eventually also on Reservoir 2 if pressure to Reservoir 2 was applied to avoid re-fluxes). With references to FIG. 2C, pressure is applied on Reservoir 2 so that Fluid 2 flows into the outlet channel. (Similarly for this purpose some pressure may be applied to Reservoir 1 to keep the flow rate of fluid 1 at 0 and avoid refluxes into Inlet channel 1). This way fluid 2 will push forward fluid 1 into the outlet channel without mixing or with minimal mixing forming in fact a column of fluid with two different segments. Then, pressure on reservoir 2 is stopped (and eventually also on reservoir 1 if pressure to reservoir 1 was applied to avoid re-fluxes). Then the process showed in FIG. 2B and FIG. 2C can be repeated to create more segments.

[0070] In another embodiment, one or more channels have the pressure applied continuously if the final column of fluid with different segments can still be obtained.

[0071] FIG. 3A shows the steps after the formation of the column of fluid with different segments. In one embodiment, the fluid column is hardened so that a fiber with the mechanical properties of a solid is formed. This way the segments remain separate. The fiber is formed inside or outside the outlet channel. The fiber is formed by different crosslinking/hardening strategies based on the nature of the starting solution. In one embodiment, the hardening is achieved by temperature variation if the fluid is thermoresponsive. In this case, the column of fluid flows in an environment with a temperature gradient to form a solid fiber.

[0072] In another embodiment, the hardening is achieved chemically and the column of fluid flows in an environment where chemical crosslinkers are present to form a solid fiber. Chemical crosslinkers are those suitable for the fluid used to produce the fibers. When the solution is alginate the chemical used is a water solution of Calcium chloride and or Barium chloride at a concentration ranging from 50 mM to 5 M. When gellan gum solution is used the hardening bath is a salt solution (sodium chloride) in a concentration ranging from 50 mM to 5 M.

[0073] In another embodiment the hardening occurs by means of an electromagnetic stimulus. In this case, the column of fluid is subject by the external stimulus (e.g. light) to form the fiber.

[0074] In another embodiment a fiber is produced using a junction made by channels of 190 m in diameter. The fiber is made of two segments that correspond to two different solutions contained in the reservoir. One solution is an alginate solution at 1.5% w/vol in water while the other is a gellan gum solution at 0.75% w/vol in 0.25M Sucrose. The fiber is produced by alternating the dispensing of the two fluids. The gellan gum segments is produced by applying a pressure of 80000 PA for 2.75 s while the alginate part is produced by applying a pressure of 150000 Pa for 0.25 s. The fiber produced is 400 m in diameter. The gellan gum segments is 3 mm long and the alginate segment is 15 mm long.

[0075] In another embodiment a fiber is produced using a junction made by channels of 190 m in diameter. The fiber is made of two segments of the same materials that correspond to two different solutions contained in the reservoir. One solution is an alginate solution at 2% w/vol in water while the other is an alginate solution at 2% w/vol phosphate buffer (PBS). The fiber is produced by alternating the dispensing of the two fluids. The alginate in PBS segment is produced by applying a pressure of 15000 Pa for 2.5 s while the alginate part is produced by applying a pressure of 200000 Pa for 0.5 s. The fiber produced is 400 m in diameter. The alginate in PBS segments is 2.5 mm long and the alginate in water segment is 10 mm long.

[0076] In one embodiment the fiber is produced with segments whose material composition changes along the fiber. The fiber is produced using a junction made by channels of 190 m in diameter. The fiber is made of two segments, one obtained from the alginate solution contained in the reservoir (alginate solution at 1.5% w/vol in water) and the other segment formed by a solution produced by mixing two other solutions at different ratios.

[0077] The fiber is produced by alternating the dispensing of the two fluids (the alginate and the solution produced after the mixing).

[0078] FIG. 3B defines some terms used in the present application such as fiber major axis, width, and length of segment. The Fiber major axis corresponds to the length of the fiber or, in other terms, the line passing through the center of the fiber section whose direction is the one of the flow in the outlet channel. The width of the segment corresponds to the diameter of the fiber or the width of the section of the fiber in case of a not-round fiber. The length of the segment corresponds to the distance between two adjacent segments along the major axis of the fiber.

[0079] The time needed to perform the stages of the diagram of FIG. 4, is referred as a Period.

[0080] An active phase is to be understood as the phase when the highest amount of pressure is applied to a reservoir, and there is flow of solution in the inlet channel, in the junction and in the outlet channel. The technical elements of reservoirs, or channels in this phase, are also considered active in this phase.

[0081] On the other hand, an inactive phase is to be understood as the phase when the lowest amount of pressure, considered residual pressure, is applied to a reservoir, and there is no flow of solution in the inlet channel connected with that reservoir. The technical elements of reservoirs, or channels in this phase, are also considered inactive in this phase.

[0082] The possibility to promote a fast change between active phase and inactive phase, by switching the pressure levels applied in the reservoirs, allows producing a fiber in a short time.

[0083] In one embodiment the pressure applied to the reservoir is equal to or higher than 1000 Pa, depending on the solutions used.

[0084] In one embodiment the relation between the flow rate in the channels and the pressure applied to the reservoirs depends on the nature of the solution.

[0085] In one embodiment the minimum time of application of pressure to the reservoirs is 100 ms.

[0086] In one embodiment the size of the channels ranges between 10 m and 5 mm in width and from 1 to 1000 mm in length.

[0087] In one embodiment the pressure of the inactive reservoirs is higher than zero to avoid backflow because of the fluid flowing from the active channel. The pressure of the inactive channels varies with the nature of the fluid used and the geometry of the channels. Such pressure varies from 0.1 to 5% of the pressure on the active reservoir.

Hardening Methods:

Hardening Outside the Outlet Channel:

[0088] In one embodiment the solutions that form the fiber are hardened outside the outlet channel by means of being in contact with salt solutions.

[0089] In one embodiment the polymeric solution that hardens to form a gel solution is gellan gum at 1% weight/volume that hardens forming a solid when placed in contact with a salt solution.

[0090] In one embodiment the polymeric solution that hardens to form a gel solution is alginate at 2% weight/volume that hardens forming a solid when placed in contact with a salt solution containing divalent cations such as Calcium or Barium.

[0091] In one embodiment the solution is made of anionic polymers such as carrageenan, alginate, gellan gum that hardens upon contact with salts. For Gellan gum monovalent cations of the salt electrically shield the negatively charged group allowing a tighter aggregation of the polymer forming a solid For Alginate divalent or trivalent cations, in addition to their electrical screening effect, bind together different negative groups also forming solids. The concentration of salts (Sodium Chloride, Calcium Chloride, barium Chloride) in solution can vary between 20 mM to 5 M. For these polymers the solution in the outlet channel containing the segments is immersed in the salt solution to form a solid fiber.

Hardening Inside the Outlet Channel with Temperature:

[0092] In one embodiment the solutions that form the segments of the fiber are hardened inside the outlet channel by a change in temperature. In another embodiment, the solution is made of a thermoresponsive polymer that is a polymer (collagen, gelatin) that forms a solid upon temperature variation. For these polymers, the solution in the outlet channel containing the segments undergoes a temperature change to form a solid. The temperature change depends on the nature of the solution, it may be between 4 C. (solution) to 37 C. (formation of a solid) for collagen at 0.4% weight/volume or 45 C. (solution) to 25 C. (formation of a solid) for gelatin at 15% weight/volume.

[0093] In another embodiment the solution is a collagen solution with the reservoir at a temperature of 4 C. that hardens forming a solid when temperature changes to 37 C.

Hardening Inside the Outlet Channel with UV Light:

[0094] In one embodiment the solutions that form the segments of the fiber comprise photoinitiators and the fibres are hardened inside the outlet channel by means of exposure to UV light.

[0095] In another embodiment the solution is made of polymers that can form a solid when irradiated by UV light (250-500 nm) in the presence of a suitable photoinitiator (such as Irgacure). The polymers may be in the family of the methacrylated or acrylated polymers (modified hyaluronic acid, modified gellan gum, modified gelatin with acrylate or methacrylate groups) carrying a double bond on the polymeric backbone. When irradiated by light the photoinitiator is activated and a chemical reaction is started that breaks those double bonds and forms new bonds between the polymeric chains and forming a solid. For these polymers the solution in the outlet channel containing the segments is irradiated by UV light to form a solid fiber.

[0096] In another embodiment the solution is methacrylated or acrylated gellan gum at 2% weight/volume with 2-Hydroxy-4-(2-hydroxyethoxy)-2-methylpropiophenon as photoinitiator at 0.05% weight/volume and the reservoir is kept in the dark, the solution can then harden when placed under UV radiation (250-500 nm wave length) for a period of time necessary for the formation of a solid (from 2 seconds to 5 minutes).

EXAMPLES

Example 1.1

[0097] FIG. 5 shows fibers with segments of different sizes. A flow sensor is used to control the flow rate of fluid 1 (dark in the figure, gellan gum 1% in 0.25M Sucrose solution). Fluid 2 consists of a solution of alginate 1.5% in water. Each step of the rules placed as reference on the bottom of the picture is 1 mm. The fibers in the picture is made using the following parameters:

Period: 3 seconds;
Time of application of pressure 1: 2.55 seconds;
Time of application of pressure 2: 0.45 seconds;
Flow rate related to pressure 1: from top to bottom 2.5, 5, 10, 20 L/min;
A pressure 2 of 7500 Pa was used to avoid re-fluxes while pressure 2 was in its inactive phase;
Size of inlet channels=size of outlet channels=190390 m;
Diameter of fiber produced: 400 m;

[0098] In these conditions the relation between pressure applied and flowrate is as follow:

For Gellan gum 1%:

[0099]

TABLE-US-00001 Flow Rate (L/min) Pressure 1 (Pa) 2.5 50000 5 71200 10 89200 20 105000
For alginate 1.5%

TABLE-US-00002 Flow Rate (L/min) Pressure 2 (Pa) 223 200000

Example 1.1.1

[0100] When different lengths of the segments in the fiber are needed, other parameters can be used. A higher flow rate relates with longer segments both for the gellan gum and for alginate segments.

For Gellan gum 1%

[0101]

TABLE-US-00003 Flow Rate (L/min) Pressure 1 (Pa) 0.6 25000 6.2 75000 7.5 82000 15 95000
For alginate 1.5%

TABLE-US-00004 Flow Rate (L/min) Pressure 2 (Pa) 2.5 4600 5 8000 7.5 11300 10 15000 15 23000 15.3 25000 33.5 50000 53.5 75000 91 100000 151 150000

[0102] The length of the segments relates to the flow rate (or pressure) as follows:

Length=Volume/Section Area

[0103] Volume=FlowRatetime of application of pressure
Section Area=(D{circumflex over ()}2)/4 with D the diameter of the fiber produced.

[0104] The solution coming from the outlet channel is hardened using a hardening bath composed of a solution of 100 mM Calcium Chloride in water.

Example 1.2

[0105] FIG. 6 shows fibers similar to FIG. 5 but made with different parameters. Each step of the ruler placed as reference on the bottom of the picture is 1 mm. The segments made by fluid 1 (dark) are of the same size but the distance is changed. From top to bottom:

TABLE-US-00005 Time Length Length of of of flow Time of segment segment Flowrate Pressure of Pressure application made of made of of fluid 1 of fluid fluid of fluid of pressure fluid 1 fluid 2 (uL/min) 1 (Pa) 1 (s) 2 (PA) 2 (s) (mm) (mm) 7.5 82000 2.55 200000 0.45 2.5 12 10 89200 1.95 200000 1.05 2.5 26 5.5 72000 3.5 200000 1.5 2.5 42

[0106] A pressure 2 of 7500 Pa was used to avoid re-fluxes while reservoir 2 was in its inactive phase.

Size of inlet channels=size of outlet channels=190390 m
Diameter of fiber: 400 m

Example 1.3

[0107] FIG. 7 shows a fiber made of three components (Gellan gum 1%) with different dyes representing different loaded molecules. The fiber was made with a junction composed of three inlets and 1 outlet of size 190390 m. Each inlet channel was connected to a reservoir containing a gellan gum solution at 1% in 0.25M sucrose of different color (red, blue and white.fwdarw.R, B, W respectively)) and the fiber was made by alternating the flow of the three fluids into the outlet channel. The flowrate of the three fluids was 10 uL/min for 2.55 seconds which correspond to an applied pressure of 89200 Pa. The solution coming from the outlet channel was hardened using a hardening bath composed of a solution of 100 mM Calcium Chloride in water.

Example 1.4

[0108] Similarly, to example 1.3 the fiber is made of three components (collagen). The solutions were made from a starting collagen solution ranging from 0.05 to 0.4% in 0.2% acetic acid. To this solution was added 10% in volume of concentrate and the pH was adjusted to pH 7 with the addition of NaOH. The system (reservoir, inlet channels, junction) is kept at 4 C. while the outlet channel was placed at 37 C. for hardening.

Example 1.5

[0109] Similarly, to example 1.3 the fiber is made with three components (gelatin). The solutions were made from a starting gelatin solution ranging from 1 to 20% in water. The system (reservoir, inlet channels, junction) is kept at 39 C. while the outlet channel was placed at 4 C. for hardening.

Example 1.6

[0110] Similarly, to example 1.3 the fiber was made with three components (methacrylated gellan gum). The solutions were made from a starting methacrylated gellan gum solution ranging from 0.5 to 4% in water. The system (reservoir, inlet channels, junction) is kept in the dark while the outlet channel was placed under UV light for hardening for a period of time that ranges from 1 second to 10 minutes.

Example 1.7

[0111] Similarly, to example 1.3 the fiber is made with two components. One component was produced from starting solution of gellan gum at 1% in water. The flowrate of the gellan gum was 10 uL/min for 2.55 seconds which correspond to an applied pressure of 89200 Pa. The second component was produced by mixing at different ratios two gellan gum solution at 1% in 0.25M Sucrose containing different cell lineages in suspension, mesenchymal/stromal stem cells and endothelial cells.

Example 1.8

[0112] Similarly, to example 1.3 the fiber was made with two components. One component was produced starting from a solution of gellan gum at 1% in water. The flowrate of the gellan gum was 10 uL/min for 2.55 seconds which correspond to an applied pressure of 89200 Pa. The second component was produced by mixing two different solutions, one of pure gellan gum at 1% in 0.25M Sucrose the other of 0.5% hyaluronic acid and 1% gellan gum in 0.25M sucrose.

Example 1.9

[0113] Similarly, to example 1.3 the fiber was made with two components. One component was produced from a starting solution of gellan gum at 1% in water. The flowrate of the gellan gum was 10 uL/min for 2.55 seconds which correspond to an applied pressure of 89200 Pa. The second component is produced by mixing two different solutions, one of pure gellan gum at 1% in 0.25M Sucrose the other of gellan gum at 1% and 0.5% chondroitin sulfate in 0.25M sucrose.

Example 2.1

[0114] FIG. 8 shows solid particles entrapped in a segment of the fiber. Polylactic acid microparticles were mixed in a solution of gellan gum at 1% to obtain a suspension of particles in the polymeric solution (FIG. 8, inset B). A two inlet junction was used to obtain a continuous fiber of alginate containing segments of gellan gum loaded with micro particles (FIG. 8, inset C). The segments containing the particles was fabricated using a flowrate of 10 uL/min for 2.55 seconds which correspond to an applied pressure of 89200 Pa (while FIG. 8, Inset A shows the magnification of the segment containing the entrapped particles).

[0115] In one embodiments the particles are loaded with drugs and the fiber is used to provide sustained drug release for medical use.

Example 2.2

[0116] FIG. 9 shows the segment containing the particles removed from the fiber. The initial fiber was made by two distinct materials namely a gellan gum (1%) containing Polylactic acid microparticles and alginate 2%.

[0117] After production the fiber was placed in a solution of alginase (10 U/ml) and left overnight. One unit (U) is defined as the quantity that results in an increase the absorption at 235 nm of 1.0 per minute per mL of sodium alginate solution at pH 6.3 and 37 C. The alginase selectively degrade the alginate portion of the fiber effectively releasing from the structure intact segments made of gellan gum. FIG. 9, Inset A shows the segment using a different illumination so that the particles entrapped are clearly visible.

Example 3.1

[0118] FIG. 10 shows a fluorescent picture of living cells entrapped in one segment of the fibers. A gellan gum solution in 0.25M sucrose was used to suspend 1 million human adipose stem cells for each ml of gellan gum. This suspension was used to form hydrogel segments inside a fiber made from alginate 1.5% weight/vol in water. The fiber was incubated in standard culture condition for 24 h. After this the fiber was stained with calcein (a molecule that once metabolized by living cells gives green fluorescence) and propidium iodide (a molecule that can stain the nuclei of dead cells). In one embodiment these fibers are used as a support for cells and the fiber is used for tissue engineering and regenerative medicine. In one embodiment cells are glucose responsive cells and the fiber is used for the release of insulin and the treatment of diabetes.

Example 4.1

[0119] FIG. 11 shows a scheme to produce hydrogel patches using the fibers produced by this invention as building blocks. By assembling fibers made of segments of different materials and with different molecules in suspension or in solution a patch was made. The fibers are aligned side by side to reconstruct the desired geometry and distribution of materials and molecules on the patch. This way the patch is designed to be placed, for example, in a wound and target differently the different microenvironments that constitute the wound. Furthermore, one or more fibers or segment can contain monitoring molecules that monitor the environment of the wound. In one embodiment, a dual component fiber is inserted to monitor the pH of the wound and the presence of lactate.

Example 4.2

[0120] FIGS. 12A-12C show the successive steps to form the patch. The fibers (the building blocks of the patch) made of different segments are aligned side by side so that the desired design of the patch is obtained. FIG. 12 A shows the alignment of fibers made of two components. The design was obtained by changing the size of the segments and aligning the fibers accordingly. FIG. 12 B shows the addition of the fibers of 1 component to obtain the final bundle of fibers. The bundle of fiber is then coated with a solution of 10% gelatin at 37 C. to glue the fibers together. After leaving it at room temperature the gelatin hardens increasing the mechanical properties of the bundle and allow the fiber to be handled (FIG. 12 C).

Example 4.3

[0121] FIGS. 13A-13C show the patches. Segment 1 was made of a solution of gellan gum at 1% in water mixed with a dye (Alizating red) acting as a molecule. Segment 2 was made of a solution of gellan gum at 1% in water mixed with a dye (Alcyan blue) acting as a molecule. Segment 3 (transparent) is a solution of gellan gum at 1% in water. The left part the figure shows the patches before the coating while the right part shows the coated patches placed on a part of the. FIG. 13 A shows a wrist size patch made of two different components by bundling fibers made of components 1 and 2. FIG. 13 B shows a wrist size patch made of three different components by bundling fibers made of components 1, 2 and 3. FIG. 13 C shows a finger-tip size patch made of three different components by bundling fibers made of components 1, 2 and 3.

Example 5.1

[0122] FIG. 14 shows a fiber rolled in a spool and placed under the microscope for image analysis. The fiber was made of two gellan gum solutions at 1% in 0.25M sucrose, one with cells in suspension and the other one without cells. The solution with cells contains 1 million human adipose stem cells for each ml of gellan gum that were stained with a fluorescent green (Calcein) for observation using a fluorescent microscope. The fiber was made in 100 seconds. The segments containing cells were made by linearly increasing the flow rate from 0 L/min to 50 L/min (from 0 Pa to 121000 Pa) in 100 seconds. The segments without cells were made by applying a pressure following a sinusoidal function with a period of 1 second and an amplitude of 150000 Pa.

[0123] The final fiber has segments of different length (constant width of 400 m) containing cells. The smaller segments are in the center of the picture (close to the center of the spool marked with a X) while the longer segments are on the peripheral part of the picture. The segments produced range from 0 to 3 mm in length.

Example 5.2

[0124] FIG. 15 shows a fiber rolled in a spool and placed under the microscope for image analysis. The fiber is made of three gellan gum solutions at 1% in 0.25M sucrose, two with cells in suspension and the other without cells. The solutions with cells contain 1 million human adipose stem cells for each ml of gellan gum that were stained with a fluorescent dye. Cells from one solution were stained in green and the other were stained in red (Calcein) for observation using a fluorescent microscope. The solutions containing cells were mixed with a microfluidic mixer to create fluid containing a gradient of red and green cells. The solution was mixed starting from the solution containing green cells flowing at 5 L/min (71200 Pa). Then the flowrate was linearly decreased to 0 in 120 seconds. During the same 120 seconds period the flowrate of the solution containing red cells was increased from 0 to 5 uL/min. The solution coming from the mixer was then used to create the segments of the fiber containing cells. The segments of the fiber without cells were made by applying a pressure of 150000 Pa for 0.6 seconds over a period of 3 seconds.