Alzheimer’s disease (AD) is a common neurodegenerative disorder with limited effective treatments. Cod skin collagen peptides (CSCPs) have neuroprotective potential for AD but face poor bioavailability—due to gastrointestinal enzyme cleavage and hepatic first-pass metabolism—prompting this study to develop a nanodelivery system to enhance CSCPs’ efficacy. Trimethyl chitosan (TMC)-based CSCP-loaded nanoparticles (CSCPs-NPs) were synthesized via ionic gelation, characterized for physicochemical properties, and tested in a D-galactose-induced AD mouse model (six groups: normal control, model, CSCPs low/high dose, blank NPs, CSCPs-NPs) using behavioral tests, histopathology, immunohistochemistry, and ELISA. CSCPs-NPs had a hydrodynamic diameter of 93.25 ± 21.52 nm, polydispersity index of 0.18 ± 0.13, 61.17% encapsulation efficiency, and sustained 24 h release. In AD mice, CSCPs-NPs significantly improved cognitive function and motor coordination, reduced hippocampal atrophy, preserved neurons, and mitigated oxidative stress, neuroinflammation, and apoptosis (upregulated Bcl-2, downregulated Bax)—effects matching high-dose free CSCPs. This TMC-based nanoformulation enhances CSCPs’ bioavailability and provides a promising strategy for AD intervention.

Excessive short-term ethanol intake often causes acute intoxication and multi-organ damage, especially to the liver and brain. Thus, developing safe and effective preparations for hangover relief, liver protection, and brain function regulation is of great practical significance. In this study, we fabricated a thermosensitive chitosan (CS)–sea cucumber peptide (SCP) hydrogel (CS–SCP gel) loaded with SCP using NaHCO₃ as a crosslinker and characterized its properties. Kunming mouse models of anti-intoxication and acute alcohol-induced liver and brain injuries were established. The anti-intoxication and organ-protective effects of the CS–SCP gel were comprehensively evaluated through behavioral observation, liver histopathology, and biochemical assays of serum and liver, kidney, and brain tissues. The CS–SCP gel exhibited a phase transition temperature of 35.7 °C, a water absorption rate of 1015.47%, and a cumulative peptide release of 74.83% within 330 min. In mice, it prolonged the latency to drunkenness; shortened alcohol-induced sleep and sobering time; reduced blood ethanol, transaminase, and lipid levels; upregulated hepatic antioxidant enzymes; downregulated pro-inflammatory cytokines, and alleviated lipid peroxidation. It also enhanced brain antioxidant capacity, suppressed cerebral inflammatory cytokines, and maintained cholinergic neurotransmitter homeostasis. Collectively, with sustained release, CS–SCP gel is expected to prolong the pharmacological action of SCP, enhance therapeutic efficacy, and protect against alcohol-induced liver and brain injury through the regulation of oxidative stress and attenuation of inflammation.