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Peptides, which are short chains formed by amino acids linked via peptide bonds, are the basic units of proteins and play a role in various biological processes such as hormone regulation, immune responses, and cellular signal transduction. They exhibit characteristics such as structural diversity, high biological activity, low toxicity, and strong designability, making them important research subjects in the fields of pharmaceuticals, cosmetics, and biotechnology. In recent years, with advancements in synthesis techniques, characterisation methods, and delivery systems, peptides and their derivatives have demonstrated broader application prospects. This article focuses on several typical types of peptides and their applications: peptide inhibitors, cosmetic peptides, functional peptides, and peptide synthesis reagents, and briefly discusses their roles and significance in contemporary science.

Effects of Peptide Inhibitors
Peptide inhibitors are peptide molecules that can interfere with specific biological processes. They intervene in disease-related pathways by inhibiting enzyme activity, blocking receptor signals, or disrupting protein-protein interactions, thereby becoming important tools in drug development. For example, certain peptide inhibitors can target proteins that promote tumour growth, invasion, or drug resistance, offering treatment strategies with greater selectivity and potentially lower side effects compared to traditional chemotherapy. Additionally, peptide inhibitors have demonstrated potential therapeutic value in fields such as cardiovascular diseases, autoimmune diseases, and infectious diseases. However, peptide inhibitors still face challenges related to stability, pharmacokinetics, delivery, and immunogenicity, which require improvements through chemical modifications, carrier systems, and precise targeting.

Application of Cosmetic Peptides
Cosmetic peptides play a significant role in the beauty and skincare industry. By promoting the synthesis of collagen and other matrix proteins, enhancing skin elasticity, and accelerating cell turnover, cosmetic peptides are widely marketed as anti-ageing and reparative ingredients. Typical examples include palmitoyl pentapeptide-4 (Matrixyl), which is believed to stimulate collagen synthesis and improve wrinkles; and peptides like acetyl hexapeptide-8 (Argireline), which reduce the formation of expression lines by mimicking muscle relaxation. In addition to anti-wrinkle effects, beauty peptides can also strengthen the skin barrier, alleviate inflammation, and enhance skin hydration. While the intensity and durability of their effects vary across products and individuals, the introduction of peptide technology has indeed driven innovation in cosmetic science.

Functional Peptides and Their Applications
Functional peptides emphasise specific biological activities for therapeutic or health-promoting purposes. Antimicrobial peptides (AMPs) have garnered significant attention for their ability to combat antibiotic-resistant bacteria, often by interacting with bacterial membranes to eliminate pathogens, making them strong candidates for novel anti-infective drugs. Additionally, cell-penetrating peptides (CPPs) can deliver drugs, genes, or other therapeutic molecules into cells, enhancing treatment efficacy. Functional peptides also include active peptides with antioxidant, immunomodulatory, and metabolic regulatory properties, among others, and are considered an important component of future personalised therapy and multi-target drug design. With advancements in synthesis and screening technologies, the potential of functional peptides in preclinical research and clinical translation is increasingly evident.

Peptide Synthesis Reagents and Techniques
Peptide synthesis reagents are essential tools and the foundation for peptide preparation in laboratories. Modern peptide synthesis primarily relies on solid-phase peptide synthesis (SPPS), where researchers sequentially attach amino acids to a solid support for easy elution, purification, and analysis. The development of SPPS has enabled the synthesis of high-purity, high-yield peptides, driving advancements in automated synthesis, large-scale production, and the exploration of peptide drugs. To enhance synthesis efficiency, researchers continuously refine coupling reagents, protective group systems, elution conditions, and other processes, even developing environmentally friendly, low-toxicity green synthesis strategies. Additionally, catalysts, flow synthesis, and miniaturised synthesis platforms are driving peptide synthesis technology toward higher throughput and lower costs.

Future Outlook and Challenges
Overall, peptides and related fields are deepening interdisciplinary integration: chemistry, pharmacy, materials science, bioinformatics, and other disciplines are synergistically driving the design, characterisation, delivery, and application of peptides. Future challenges include enhancing the stability, in vivo kinetic predictability, and long-term safety of peptide drugs and peptide-based cosmetics; reducing synthesis costs, improving yields, and scaling up production capacity; and establishing a more comprehensive regulatory framework to ensure the safety and efficacy of clinical translation and consumer use. As technology advances and demand for health and aesthetics grows, peptides will play an increasingly important role in the fields of pharmaceuticals, cosmetics, and biotechnology, becoming a key driver of biomedical innovation and industrialisation.