Polydopamine Nanoparticles Modulating Stimuli-Responsive PNIPAM Hydrogels with Cell/Tissue Adhesiveness

Stimuli-responsive hydrogels can respond to stimuli by phase transformation or volume change and exhibit specific functions. Near-infrared (NIR)-responsive hydrogel is a type of stimuli-responsive hydrogel, which can be precisely controlled by altering the radiation intensity, exposure time of the light source, and irradiation sites. Here, polydopamine nanoparticles (PDA-NPs) were introduced into a poly­(<i>N</i>-isopropylacrylamide) (PNIPAM) network to fabricate a PDA-NPs/PNIPAM hydrogel with NIR responsibility, self-healing ability, and cell/tissue adhesiveness. After incorporation of PDA-NPs into the hydrogel, the PDA-NPs/PNIPAM hydrogel showed phase transitions and volume changes in response to NIR. Thus, the hydrogel can achieve triple response effects, including pulsatile drug release, NIR-driven actuation, and NIR-assisted healing. After coating PDA-NPs onto hydrogel surfaces, the hydrogel showed improved cell affinity, good tissue adhesiveness, and growth factor/protein immobilization ability because of reactive catechol groups on PDA-NPs. The tissue adhesion strength to porcine skin was as high as 90 KPa. <i>In vivo</i> full-skin defect experiments demonstrated that PDA-NPs coating on the hydrogel and an immobilized growth factor had a synergistic effect on accelerating wound healing. In summary, we combined thermosensitive PNIPAM and mussel-inspired PDA-NPs to form a NIR-responsive hydrogel, which may have potential applications for chemical and physical therapies

Comparison of survival analysis of different clinicopathological factors affecting PFS in 122 patients with NECC in the external validation cohort.

A, Serum NSE; B, Tumor size; C, Stage; D, Stromal Invasion; E, Lymph node metastasis; F, Distant metastasis. (TIF)</p

Univariate and multivariate analysis of 3-year overall survival of NECC patients in the external validation cohort (N = 122).

Univariate and multivariate analysis of 3-year overall survival of NECC patients in the external validation cohort (N = 122).</p

Comparison of overall survival between high- and low-risk groups.

A, training cohort; B, internal validation cohort; C, external validation cohort.</p

Univariate and multivariate analysis of 3-year progression-free survival of NECC patients in the external validation cohort (N = 122).

Univariate and multivariate analysis of 3-year progression-free survival of NECC patients in the external validation cohort (N = 122).</p

Comparison of survival analysis of different clinicopathological factors affecting OS in 122 patients with NECC in the external validation cohort.

A, Serum NSE; B. Tumor size; C, Stage; D, Stromal Invasion; E, Lymph node metastasis; F, Cycles of chemotherapy. (TIF)</p

Univariate analysis of immunohistochemical markers of 3-year progression-free survival and 3-year overall survival of NECC patients in the external validation cohort (N = 122).

Univariate analysis of immunohistochemical markers of 3-year progression-free survival and 3-year overall survival of NECC patients in the external validation cohort (N = 122).</p

The clinicopathologic characteristics of NECC patients in the external validation cohort.

The clinicopathologic characteristics of NECC patients in the external validation cohort.</p

The clinicopathologic characteristics of NECC patients in the training and internal validation cohorts.

The clinicopathologic characteristics of NECC patients in the training and internal validation cohorts.</p

Univariate and multivariate analysis of 3-year and 5-year overall survival of NECC patients in the training cohort (N = 376).

Univariate and multivariate analysis of 3-year and 5-year overall survival of NECC patients in the training cohort (N = 376).</p