Phenylboronic acid (PBA) is a widely exploited glucose-sensitive element for constructing glucose-responsive hydrogels to enable smart insulin delivery. However, its relatively high intrinsic pK_a affects its binding with glucose under physiological conditions and thus limits its application. Herein, we developed a series of boronate-containing PLP–PBA polymers by conjugating glucose-sensitive 3-aminophenylboronic acid (3-PBA) onto the backbone of a metabolite-derived, pH-responsive poly-L-lysine isophthalamide (PLP) polymer with a pK_a value of 4.4 at various substitution degrees. Dual-responsive LME–(PLP–PBA) hydrogels were further synthesized by crosslinking the PLP–PBA polymers with L-lysine methyl ester (LME). The rheological properties and swelling ratio of the hydrogel could be manipulated by the PBA grafting degree and crosslinking ratio. With the increase of pH and glucose concentration, the pore size of the hydrogel enhanced, thus promoting the release of loaded insulin. Under physiological conditions, the hydrogel with optimal formulation could establish acute pH-responsive and glucose-responsive insulin release. The development of this dual-responsive hydrogel suggests a strategy to overcome the high pK_a problem associated with PBA and provide a promising delivery system for smart insulin delivery.

PEGylated micelles have been widely used for tumour therapy. Although PEGylation can prolong the blood circulation time, there is only less than 5% of administered micelles that can be transported to tumour sites and over 95% are cleared by the reticuloendothelial system (RES). Besides, the limited intracellular drug release also restricts their efficacy. To improve the therapeutic efficacy of PEGylated micelles, a safe, simple and efficient hybrid micellar system, composed of poly(aminoethyl ethylene phosphate)-poly(L-lactic acid) (PAEEP-PLLA) and poly(ethylene glycol)-poly(L-lactic acid) (PEG-PLLA), was developed. The hybrid micelles significantly prolonged the blood circulation time by decreasing the plasma protein adsorption and reducing the clearance by the RES. The deposition of the hybrid micelles in the liver and spleen was reduced, and the tumour accumulation was greatly improved. In addition, the intracellular drug release of the hybrid micelles was obviously increased due to the easy degradation of PAEEP in the endo/lysosomes. The tumour growth inhibition efficiency of the hybrid micelles was much higher than that of the PEG-PLLA micelles (84.5% vs. 44.5%). Furthermore, the hybrid micelles exhibited low hemolysis and reduced deposition in normal organs, which revealed their excellent bio-safety. Therefore, we established a promising hybrid micelle system for efficient anti-tumour therapy.

Conventional aluminum adjuvants exhibit limited cellular immunity. Polyinosinic-polycytidylic acid (poly I:C) activates cytoplasmic retinoic acid-inducible gene-like receptor (RLR), triggering strong T cell activation and cellular responses. However, when applied as an adjuvant, its limited endocytosis and restricted cytoplasmic delivery diminish its effectiveness and increase its toxicity. Hybrid polymer–lipid nanoparticle (PLNP) possesses numerous benefits such as good stability, reduced drug leakage, simple fabrication, easy property modulation, and excellent reproducibility compared to the lipid nanoparticle or the polymeric vector. Here, we developed a novel cationic polymer–lipid hybrid adjuvant capable of incorporating poly I:C to enhance cellular immunity. The hepatitis B surface antigen (HBsAg) was immobilized onto poly I:C-incorprated PLNP (PPLNP) via electrostatic interactions, forming the HBsAg/PPLNP vaccine formulation. The PPLNP adjuvant largely enhanced the cellular endocytosis and cytoplasmic transport of poly I:C, activating RLR followed by promoting type I interferon (IFN) secretion. Meanwhile, PPLNP obviously enhanced the antigen uptake, prolonged antigen retention at the site of administration, and facilitated enhanced transport of antigens to lymph nodes. The HBsAg/PPLNP nanovaccine led to amplified concentrations of antigen-specific immunoglobulin G (IgG), IFN-γ, granzyme B, and an enhanced IgG2a/IgG1 ratio, alongside the FasL ⁺ /CD8 ⁺ T cell activation, favoring a T helper 1 (T _H 1)-driven immune response. PPLNP, distinguished by its biocompatibility, ease of fabrication, and effectiveness in augmenting cellular immunity, holds significant promise as a new adjuvant.

Background/Objectives: As a primary mRNA delivery platform, lipid nanoparticles (LNPs) often induce oxidative stress that compromises mRNA translation efficiency. Natural polysaccharides are known for their antioxidant properties. Methods: To lower LNP toxicity and boost mRNA delivery, we conducted a preliminary pro-proliferation screen of 34 natural polysaccharides using a CCK-8 cytotoxicity assay in murine macrophage RAW264.7 cells, serving as an initial filter for bioactivity. Subsequently, their ability to improve LNP-mediated transfection efficiency was validated in HEK293T cells—a standard model for quantifying protein expression. After that, Ganoderma lucidum polysaccharide (GLP) was selected as a lead candidate for potential adjuvant. Results: Formulated into mRNA-LNPs by first preparing the LNPs via a one-step nano-precipitation process, followed by direct incorporation of GLP through mixing, the resulting GLP-LNP formulation significantly alleviated intracellular oxidative stress by elevating glutathione and superoxide dismutase while reducing malondialdehyde, indicating restored redox homeostasis. This modulation correlated with markedly enhanced transfection efficiency, achieving significantly higher protein expression both in vitro (3.2-fold) and in vivo (2.1-fold) compared to LNP alone. Mechanism studies implicated the activation of the nuclear factor erythroid 2-Related Factor 2 (Nrf2) pathway in this protective effect. Conclusions: We conclude that GLP represents a novel adjuvant paradigm that concurrently enhances mRNA transfection and mitigates oxidative toxicity, demonstrating significant potential for advanced vaccinology.

As a non-invasive mucosal immunization strategy, intranasal vaccines are highly promising for preventing respiratory infectious diseases. Among them, recombinant subunit vaccines represent a safe and ideal option, as they induce targeted mucosal immunity without the safety risks associated with live-vectored or nucleic acid vaccines. However, nasal mucosal defenses rapidly clear antigens before immune activation, limiting protective efficacy. Therefore, intranasal vaccine adjuvants—key regulators of immune response intensity, duration, and type—are essential to overcome mucosal tolerance and improve immunogenicity. Based on a systematic search and analysis of 127 peer-reviewed articles (2010–2026) in PubMed, Web of Science, and Embase, this study comprehensively summarizes the mechanisms, applications, and limitations of existing and candidate adjuvants for intranasal vaccines. This review systematically categorizes and discusses the nasal mucosal barrier, major adjuvant types (e.g., pattern recognition receptor agonists, cytokine adjuvants, and carrier adjuvants), and their mechanisms of action. It also identifies key bottlenecks: insufficient mucosal targeting, inconsistent global safety evaluation standards for adjuvants, and interference from pre-existing antibodies in humans. Furthermore, this review highlights future development directions, including biomimetic adjuvants, pH-responsive nanoadjuvants, and thermostable vaccine formulations. This systematic review clarifies key scientific and technical barriers in intranasal vaccine adjuvant development. The findings provide valuable references for advancing the translation of intranasal vaccines from emergency countermeasures to routine, accessible preventive tools for respiratory infectious diseases.