Stimulus-responsive hydrogel
A stimulus-responsive hydrogel with a three-dimensional network and heteropolar side chains addresses the challenge of measuring proteins by preventing aggregation and ensuring diffusion, enhancing its functionality.
Patent Information
- Application Number
- PCT/JP2024/035777
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-10-07
- Publication Date
- 2026-04-16
AI Technical Summary
Existing stimulus-responsive hydrogels struggle to incorporate and measure high-molecular-weight substances like proteins due to aggregation on the surface and inability to diffuse into the gel, limiting their functionality.
A stimulus-responsive hydrogel with a three-dimensional network structure and heteropolar molecules on its side chains, designed to bind with measurement targets like proteins, preventing electrostatic aggregation and allowing diffusion.
Enables the hydrogel to effectively measure proteins by diffusing them without aggregation, maintaining the desired stimulus response.
Smart Images
Figure JP2024035777_16042026_PF_FP_ABST
Abstract
Description
Stimulus-responsive hydrogel
[0001] This invention relates to a stimulus-responsive hydrogel.
[0002] In recent years, the market for ICT devices that acquire one's own vital information has been rapidly expanding, driven by the promotion of home healthcare and self-medication policies (Non-Patent Literature 1). For this reason, there is a growing focus on developing device elements using biocompatible and functional organic materials in biosensors and actuators. For example, research is being conducted on incorporating hydrogels (stimulus-responsive hydrogels) that have properties similar to biological tissue and possess molecular recognition capabilities into chemical sensors (Non-Patent Literature 2). To improve the signal-to-noise ratio when using stimulus-responsive hydrogels as sensor materials, it is crucial to ensure robustness by preventing shape changes other than those related to stimulus response, while simultaneously diffusing the measurement molecules within the gel.
[0003] M. Dautta et al., "Passive and wireless, implantable glucose sensing with phenylboronic acid hydrogel-interlayer RF resonators", Biosensors and Bioelectronics, vol. 151, 112004, 2020.A. Ikeda et al., "Highly sensitive hydrogel-based biosensor with dielectric resonator structure for point-of-care testing", 45th International Conference of the IEEE Engineering in Medicine and Biology Society, vol. 2023.
[0004] So far, the target molecules for measurement of stimulus-responsive hydrogels incorporated into sensors have only been low-molecular-weight molecules with a molecular size in the pm level such as glucose, and there have been no reported examples of high-molecular-weight substances such as proteins with a molecular size in the tens of nm level or larger. The reason for this is that biomolecules such as proteins tend to form aggregates, stay on the surface of the gel, and do not diffuse into the gel. In this state, the desired stimulus response does not function. Therefore, it is difficult to prepare a stimulus-responsive hydrogel with a protein as the measurement target molecule, and it is presumed that there is no report on using a protein as the measurement target molecule for stimulus-responsive hydrogels.
[0005] The present invention has been made to solve the above problems, and an object thereof is to provide a stimulus-responsive hydrogel having a high-molecular-weight substance such as a protein as a measurement target.
[0006] The stimulus-responsive hydrogel according to the present invention is a stimulus-responsive hydrogel composed of a high-molecular-weight substance having a three-dimensional network structure, having a probe molecule that binds to a measurement target substance on its side chain, and having a volume change due to the binding of the probe molecule and the measurement target substance, and having a heteropolar molecule having a polarity different from that of the probe molecule on its side chain.
[0007] As described above, according to the present invention, since the stimulus-responsive hydrogel has a heteropolar molecule having a polarity different from that of the probe molecule on its side chain, a stimulus-responsive hydrogel having a high-molecular-weight substance such as a protein as a measurement target can be provided.
[0008] FIG. 1 is a characteristic diagram showing the relationship between the position of the observation depth by a confocal laser microscope of the stimulus-responsive hydrogel according to the actually prepared embodiment and the red fluorescence intensity indicating the amount of albumin. FIG. 2 is a characteristic diagram showing the change in the swelling ratio of the stimulus-responsive hydrogel according to the GA concentration.
[0009] The following describes a stimulus-responsive hydrogel according to an embodiment of the present invention. This stimulus-responsive hydrogel is composed of a polymer material having a three-dimensional network structure and has probe molecules in its side chains that bind to the substance to be measured, and its volume changes upon binding of the probe molecules to the substance to be measured. The stimulus-responsive hydrogel according to the embodiment has heteropolar molecules in its side chains that have a different polarity from the probe molecules that react with the substance to be measured.
[0010] In the stimulus-responsive hydrogel according to the embodiment, the overall charge of the probe molecules that react with the substance to be measured is reduced to zero by the heteropolar molecules described above.
[0011] The target substance for this stimulus-responsive hydrogel is, for example, protein. The target substance can be, for example, hemoglobin, fibrin, insulin, albumin, muscle protein, etc. The three-dimensional network structure of the polymeric material in the stimulus-responsive hydrogel has a mesh size large enough for the aforementioned proteins to pass through, and the probe molecule is a molecule that binds to the protein.
[0012] The polymeric material (matrix) constituting the stimulus-responsive hydrogel can be acrylamide-based, chitosan-based, acrylic acid-based, vinyl-based, or naturally derived polymers such as gelatin or alginic acid. The probe molecule can also consist of amino groups, carbonyl groups, nitro groups, hydroxyl groups, sulfonyl groups, etc.
[0013] The polymeric substance constituting the stimulus-responsive hydrogel can be a crosslinked polymer obtained by polymerizing (addition polymerization) acrylamide using lithium phenyl(2,4,6-trimethylbenzoyl)phosphinate as a photopolymerization initiator and N-N'methyleneacrylamide as a crosslinking agent. The probe molecule can be 3-acrylamidephenylboronic acid. The heteropolar molecule can be N-[(3-dimethylamino)propyl]acrylamide.
[0014] In this embodiment, a stimulus-responsive hydrogel has probe molecules in its side chains that become charged upon reaction with the measured molecule. By modifying (binding) the network backbone of the stimulus-responsive hydrogel with heteropolar molecules having opposite charges beforehand, the net charge becomes zero, preventing electrostatic aggregation of proteins due to interactions between the protein and its side chains.
[0015] [Examples] The following will provide a more detailed explanation using examples. Below, we will describe the results of measuring glycoalbumin (GA) as the measurement molecule using the stimulus-responsive hydrogel that was actually prepared.
[0016] First, using acrylamide, 3-acrylamidephenylboronic acid, and N-[(3-dimethylamino)propyl]acrylamide as raw materials, a stimulus-responsive hydrogel was synthesized with lithium phenyl(2,4,6-trimethylbenzoyl)phosphinate as a photopolymerization initiator and N-N'methyleneacrylamide as a crosslinking agent.
[0017] A polymer is formed by polymerizing acrylamide using lithium phenyl(2,4,6-trimethylbenzoyl)phosphinate as a photopolymerization initiator and N-N'methyleneacrylamide as a crosslinking agent (addition polymerization), resulting in a crosslinked polymer that constitutes a hydrogel. The side chain of 3-acrylamidephenylboronic acid, which is modified into this polymer, acts as a probe molecule and becomes negatively charged upon reaction with GA. The side chain of N-[(3-dimethylamino)propyl]acrylamide, which is modified into this polymer, is an heteropolar molecule and has a positively charged amino group.
[0018] When the prepared stimulus-responsive hydrogel was immersed in an albumin solution having a molecular structure similar to GA, confocal laser microscopy (CLSM) observation confirmed that albumin had diffused into the interior of the stimulus-responsive hydrogel. Figure 1 shows the relationship between the observation depth of the stimulus-responsive hydrogel and the red fluorescence intensity indicating the amount of albumin.
[0019] Furthermore, when the prepared stimulus-responsive hydrogel was immersed in a GA solution containing 0-3 mg / ml, which includes the biological concentration range, the gel size (swelling rate) due to the stimulus response changed linearly with respect to the GA concentration, as shown by the black circles in Figure 2. For a GA concentration of 1 mg / dl, the swelling rate decreased by 2.4%. The white circles in Figure 2 represent the case of a stimulus-responsive hydrogel without modification by heteropolar molecules. As is clear from these results, it was found that the stimulus-responsive hydrogel according to the embodiment allows proteins such as GA to diffuse into the gel without aggregation, and exhibits the desired stimulus response.
[0020] As described above, according to the embodiments of the present invention, the stimulus-responsive hydrogel is provided with heteropolar molecules having a different polarity from the probe molecule in its side chains, thereby making it possible to provide a stimulus-responsive hydrogel for measuring macromolecules such as proteins.
[0021] It should be noted that the present invention is not limited to the embodiments described above, and it is clear that many modifications and combinations can be implemented within the technical concept of the present invention by those with ordinary skill in the art.
Claims
1. A stimulus-responsive hydrogel composed of a polymer material having a three-dimensional network structure, having probe molecules in its side chains that bind to a substance to be measured, and whose volume changes upon binding of the probe molecules to the substance to be measured, wherein the stimulus-responsive hydrogel has heteropolar molecules in its side chains that have a polarity different from that of the probe molecules.
2. A stimulus-responsive hydrogel according to claim 1, wherein the total charge of the probe molecule is reduced to zero by the heteropolar molecule.
3. A stimulus-responsive hydrogel according to claim 1 or 2, wherein the substance to be measured is a protein, the three-dimensional network structure of the polymer is such that the network size is such that the protein can pass through, and the probe molecule is a molecule that binds to the protein.
4. The stimulus-responsive hydrogel according to claim 3, wherein the polymeric substance is a crosslinked acrylamide, the probe molecule is 3-acrylamidephenylboronic acid, and the heteropolar molecule is N-[(3-dimethylamino)propyl]acrylamide.