Hydrogel particle and method for producing same, cell or cell structure each enclosing hydrogel particle therein, method for evaluating activity of cell using hydrogel particle, and use of hydrogel particle as sustained release preparation

A method for producing a hydrogel particle, comprising:

• mixing a first hydrogel with magnetic material particles, to thereby provide a first slurry comprising the first hydrogel and the magnetic material particles;
• heating the first slurry or adding a phase separation inducer to the first slurry, and particulating the first hydrogel comprising the magnetic material particles, to thereby obtain magnetic material particle-containing microparticles, wherein the magnetic material particles are dispersed in the first hydrogel;
• mixing a second hydrogel different in degree of crosslinking from the first hydrogel with the magnetic material particle-containing microparticles, to thereby provide a second slurry comprising the second hydrogel and the magnetic material particle-containing microparticles, wherein the crosslinking is formed with a crosslinking agent;
• and
• heating the second slurry or adding a phase separation inducer to the second slurry, and particulating the second hydrogel comprising the magnetic material particle-containing microparticles.

A method for evaluating cell activity of living cells, comprising:

• introducing a hydrogel particle into living cells, the hydrogel particle comprising a domain formed of a first hydrogel, a matrix encapsulating the domain and formed of a second hydrogel different in degree of crosslinking from the first hydrogel, and magnetic material particles supported on at least the first hydrogel, wherein the crosslinking is formed with a crosslinking agent, and the magnetic material particles are dispersed in the first hydrogel;
• obtaining an MRI image of the living cells by use of a signal derived from the magnetic material particles;
• and
• evaluating cell activity of the living cells based on the MRI image obtained.

A process comprising:

• administrating a hydrogel particle as a sustained-release formulation to a patient,
• wherein the hydrogel particle comprises:
• a domain formed of a first hydrogel;
• a matrix encapsulating the domain and formed of a second hydrogel different in degree of crosslinking from the first hydrogel, wherein the crosslinking is formed with a crosslinking agent;
• magnetic material particles supported on at least the first hydrogel;
• and
• at least one drug supported on at least one of the first hydrogel and the second hydrogel,
• wherein the magnetic material particles are dispersed in the first hydrogel.