Journal: Frontiers in Bioengineering and Biotechnology

Article Title: pH-responsive Zn 2+ -coordinated gellan gum/γ-polyglutamic acid hydrogel microspheres as functional biomaterials for intra-articular delivery: physicochemical design, smart release, and chondroprotective performance in osteoarthritis

doi: 10.3389/fbioe.2026.1924086

Figure Lengend Snippet: qPCR primer information.

Article Snippet: The sections were subsequently reacted with primary antibodies targeting COL2A1 (Proteintech, 28459-1-AP), MMP13 (Proteintech, 18165-1-AP), p-PI3K (HUABIO, HA721672), and p-AKT (Proteintech, 66444-1-Ig) for 16 h at 4 °C.

Techniques: Sequencing

Journal: Frontiers in Bioengineering and Biotechnology

Article Title: pH-responsive Zn 2+ -coordinated gellan gum/γ-polyglutamic acid hydrogel microspheres as functional biomaterials for intra-articular delivery: physicochemical design, smart release, and chondroprotective performance in osteoarthritis

doi: 10.3389/fbioe.2026.1924086

Figure Lengend Snippet: PGG-Zn@Cur restored matrix metabolic homeostasis in IL-1β-stimulated chondrocytes. (A) Representative immunofluorescence images of COL2A1 in chondrocytes after different treatments. COL2A1 was stained red, and nuclei were counterstained with DAPI. (B) Representative immunofluorescence images of MMP13 in chondrocytes after different treatments. MMP13 was stained green, and nuclei were counterstained with DAPI. (C) Quantitative analysis of relative fluorescence intensity for COL2A1 and MMP13 based on immunofluorescence staining. IL-1β stimulation decreased COL2A1 expression and increased MMP13 accumulation, whereas PGG-Zn@Cur treatment restored COL2A1 fluorescence intensity and suppressed MMP13-positive signals. (D–G) RT-qPCR analysis of cartilage matrix metabolism-related genes, including anabolic markers Col2a1 and Aggrecan, and catabolic markers Mmp13 and Adamts5, in chondrocytes after the indicated treatments. (H) Representative Western blot images of iNOS, COL2A1, MMP13, and ACAN protein expression, together with heatmap-based quantitative analysis of Western blot results across different treatment groups. β-Actin was used as the loading control. ( n = 3, Scale bar: 10 μm *: p < 0.05; **: p < 0.01; ***: p < 0.001; ****: p < 0.0001; ns: no significant).

Article Snippet: The sections were subsequently reacted with primary antibodies targeting COL2A1 (Proteintech, 28459-1-AP), MMP13 (Proteintech, 18165-1-AP), p-PI3K (HUABIO, HA721672), and p-AKT (Proteintech, 66444-1-Ig) for 16 h at 4 °C.

Techniques: Immunofluorescence, Staining, Analysis, Fluorescence, Expressing, Quantitative RT-PCR, Western Blot, Control

Journal: Frontiers in Bioengineering and Biotechnology

Article Title: pH-responsive Zn 2+ -coordinated gellan gum/γ-polyglutamic acid hydrogel microspheres as functional biomaterials for intra-articular delivery: physicochemical design, smart release, and chondroprotective performance in osteoarthritis

doi: 10.3389/fbioe.2026.1924086

Figure Lengend Snippet: PGG-Zn@Cur attenuated PI3K-AKT activation and apoptosis-associated responses in IL-1β-stimulated chondrocytes. (A) Schematic workflow of RNA sequencing and subsequent experimental validation. (B) Heatmap of representative differentially expressed genes related to cartilage matrix metabolism, inflammation, apoptosis, and PI3K-AKT-associated signaling. (C) Volcano plot showing differentially expressed genes between the indicated groups, with representative genes related to cartilage homeostasis, apoptosis, and PI3K-AKT signaling labeled. (D) GO enrichment analysis of differentially expressed genes, including biological process, cellular component, and molecular function categories. (E) KEGG pathway enrichment analysis, with the PI3K-AKT signaling pathway highlighted as a candidate pathway. (F) Representative immunofluorescence images of p-PI3K, p-AKT, Cl-Caspase3, and COL2A1 in chondrocytes after different treatments. Nuclei were counterstained with DAPI. (G) Quantitative analysis of p-PI3K, p-AKT, Cl-Caspase3, and COL2A1 fluorescence intensity. (H) Representative Western blot images of PI3K-AKT pathway- and apoptosis-related proteins, including p-PI3K, PI3K, p-AKT, AKT, Cleaved-Caspase3, Caspase3, Bax, and BCL2. β-Actin was used as the loading control. (I) Heatmap-based quantitative analysis of Western blot results, summarizing changes in p-PI3K/PI3K, p-AKT/AKT, Cleaved-Caspase3/Caspase3, Bax/β-Actin, and BCL2/β-Actin across different groups. ( n = 3, Scale bar: 10 μm *: p < 0.05; **: p < 0.01; ***: p < 0.001; ****: p < 0.0001; ns: not significant).

Article Snippet: The sections were subsequently reacted with primary antibodies targeting COL2A1 (Proteintech, 28459-1-AP), MMP13 (Proteintech, 18165-1-AP), p-PI3K (HUABIO, HA721672), and p-AKT (Proteintech, 66444-1-Ig) for 16 h at 4 °C.

Techniques: Activation Assay, RNA Sequencing, Biomarker Discovery, Labeling, Analysis, Immunofluorescence, Fluorescence, Western Blot, Control

Journal: Frontiers in Bioengineering and Biotechnology

Article Title: pH-responsive Zn 2+ -coordinated gellan gum/γ-polyglutamic acid hydrogel microspheres as functional biomaterials for intra-articular delivery: physicochemical design, smart release, and chondroprotective performance in osteoarthritis

doi: 10.3389/fbioe.2026.1924086

Figure Lengend Snippet: PGG-Zn@Cur attenuates OA-associated cartilage degeneration and preserves matrix homeostasis in vivo . (A) Representative Safranin O/Fast Green staining images of knee joint cartilage from the Sham, OA, OA+ PGG-Zn, OA+ Cur, and OA+ PGG-Zn@Cur groups. (B) Representative immunofluorescence images of COL2A1 and MMP13 in articular cartilage from different groups. Nuclei were counterstained with DAPI. (C, D) Quantitative analysis of cartilage degeneration using OARSI scores and modified Mankin’s scores. (E) Quantitative analysis of COL2A1 and MMP13 fluorescence intensity in articular cartilage. ( n = 5 mice per group, Scale bar: 50 μm *: p < 0.05; **: p < 0.01; ***: p < 0.001; ****: p < 0.0001; ns: not significant).

Article Snippet: The sections were subsequently reacted with primary antibodies targeting COL2A1 (Proteintech, 28459-1-AP), MMP13 (Proteintech, 18165-1-AP), p-PI3K (HUABIO, HA721672), and p-AKT (Proteintech, 66444-1-Ig) for 16 h at 4 °C.

Techniques: In Vivo, Staining, Immunofluorescence, Analysis, Modification, Fluorescence

Journal: Frontiers in Bioengineering and Biotechnology

Article Title: pH-responsive Zn 2+ -coordinated gellan gum/γ-polyglutamic acid hydrogel microspheres as functional biomaterials for intra-articular delivery: physicochemical design, smart release, and chondroprotective performance in osteoarthritis

doi: 10.3389/fbioe.2026.1924086

Figure Lengend Snippet: PGG-Zn@Cur attenuates PI3K-AKT pathway activation and apoptosis-associated cartilage damage in vivo . (A) Representative immunofluorescence images of p-PI3K, p-AKT, and COL2A1 in articular cartilage from the Sham, OA, OA+ PGG-Zn, OA+ Cur, and OA+ PGG-Zn@Cur groups. Nuclei were counterstained with DAPI. (B) Representative TUNEL staining images of articular cartilage from different groups. (C) Quantitative analysis of p-PI3K, p-AKT, and COL2A1 fluorescence intensity in articular cartilage. (D) Quantitative analysis of TUNEL-positive chondrocytes in articular cartilage. ( n = 5 mice per group, Scale bar: 50 μm *: p < 0.05; **: p < 0.01; ***: p < 0.001; ****: p < 0.0001; ns: not significant).

Article Snippet: The sections were subsequently reacted with primary antibodies targeting COL2A1 (Proteintech, 28459-1-AP), MMP13 (Proteintech, 18165-1-AP), p-PI3K (HUABIO, HA721672), and p-AKT (Proteintech, 66444-1-Ig) for 16 h at 4 °C.

Techniques: Activation Assay, In Vivo, Immunofluorescence, TUNEL Assay, Staining, Analysis, Fluorescence