## 4 Nanostructured Systems for Immunotherapeutic Delivery in Non- Malignant Applications
### Infectious Diseases  
Infectious diseases are posing a growing danger to both public health and medical systems. Inappropriate antimicrobial drug prescription and the overuse and/or misuse of antibiotics have contributed to the present antimicrobial resistance crisis. These factors boost microbial pathogenicity and allow bacteria to evade the host's immune response beneath the protection of a biofilm. The rise of multidrug-resistant microbial strains has disarmed patients and doctors in the fight against severe infectious diseases. Therefore, in order to address the challenges posed by current infectious disease management approaches (e.g., insufficient efficacy, toxicity, and the development of drug tolerance), new treatment strategies have to be adopted [118; 119]. In this context, immunotherapies have been proposed as a potential solution, given their ability to enhance the host's immune system toward combating acquired infections. These therapies, including monoclonal antibodies and vaccines, effectively modulate the host's innate and adaptive immune responses, providing alternative strategies for treating pathogenic infections and advancing our understanding of pathogen-host immune interactions. For better clarity, Figure 6 offers a visual representation of the potential benefits of immunotherapy in treating infected patients, showing how therapeutic agents can target immune checkpoints to restore effective immune control over infections. Conventional vaccines have benefited from certain advancements over the years, yet improvements are still necessary to avoid their associated drawbacks. Vaccines have been linked with issues like low immunogenicity, toxicity, instability, and the necessity for multiple administrations [120]. Moreover, the effective internalization of antigens by immune cells is vital for inducing a robust immunological response, indicating the advantages that different carriers may bring in delivering vaccination antigens [43]. In this context, nanotechnology has significantly progressed the creation of vaccines, which have recently been integrated into novel formulations. The utilization of different nanoparticles provides important benefits, including excellent stability, simplified administration, and improved effectiveness. Nanocarrier-based delivery systems also enhance both cellular and humoral immune responses, improve antigen immunogenicity, and enable targeted delivery and controlled release. In addition, they can be equipped with adjuvants or surface modifiers to regulate the release and dispersion of vaccine constituents [16; 120; 121]. The crucial role of nanotechnology in vaccine formulations for preventing severe outcomes and pathogen mutations was recently demonstrated through the success of the nanoparticle-based Moderna and Pfizer/BioNTech COVID-19 vaccines [38; 122; 123]. This precedent underscores the promising future of nanotechnology in vaccine development, marking the worldwide implementation of a new generation of vaccines. In more detail, COVID-19 vaccines employ LNPs encapsulated with therapeutic nucleic acids (TNA), being the most well-known current example of a clinically accepted delivery nanosystem. Nonetheless, LNPs loaded with TNA have also shown promise for managing other infectious diseases [38]. Several such conditions include, but are not limited to, influenza [124; 125], cytomegalovirus [56; 126], Zika virus [51], chikungunya virus [59], human immunodeficiency virus (HIV) [127; 128], hepatitis B [129; 130; 131], hepatitis C [132; 133; 134], and genital herpes [135]. Other nanomaterials have also been considered valuable as carriers of vaccine antigens. Nanoparticle platforms, including lipid nanoparticles, nanoemulsions, virus-like particles (VLPs), polymeric nanoparticles, liposomes, micelles, and polymeric micelles, are valuable carriers of vaccine antigens due to their ability to enhance antigen stability and efficacy.