In the treatment of brain diseases, most potent drugs that have been developed exhibit poor therapeutic outcomes resulting from the inability of a therapeutic amount of the drug to reach the brain. These drugs do not exhibit targeted drug delivery mechanisms, resulting in a high concentration of the drugs in vital organs leading to drug toxicity. Chitosan (CS) is a natural-based polymer. It has unique properties such as good biodegradability, biocompatibility, mucoadhesive properties, and it has been approved for biomedical applications. It has been used to develop nanocarriers for brain targeting via intranasal administration. Nanocarriers such as nanoparticles, in situ gels, nanoemulsions, and liposomes have been developed. In vitro and in vivo studies revealed that these nanocarriers exhibited enhanced drug uptake to the brain with reduced side effects resulting from the prolonged contact time of the nanocarriers with the nasal mucosa, the surface charge of the nanocarriers, the nano size of the nanocarriers, and their capability to stretch the tight junctions within the nasal mucosa. The aforementioned unique properties make chitosan a potential material for the development of nanocarriers for targeted drug delivery to the brain. This review will focus on chitosan-based carriers for brain targeting.

Nanogels are drug delivery systems that can bypass the blood-brain barrier and deliver drugs to the desired site when administered intranasally. They have been used as a drug delivery platform for the management of brain diseases such as Alzheimer disease, migraine, schizophrenia and depression. nanogels have also been developed as vaccine carriers for the protection of bacterial infections such as influenza, meningitis, pneumonia and as veterinary vaccine carriers for the protection of animals from encephalomyelitis and mouth to foot disease. It has been developed as vaccine carriers for the prevention of lifestyle disease such as obesity. Intranasal administration of therapeutics using nanogels for the management of brain diseases revealed that the drug transportation was via the olfactory nerve pathway resulting in rapid drug delivery to the brain with excellent neuroprotective effect. The application of nanogels as vaccine carriers also induced significant responses associated with protective immunity against selected bacterial and viral infections. This review provides a detailed information on the enhanced therapeutic effects, mechanisms and biological efficacy of nanogels for intranasal administration.

Colorectal cancer is a common cancer in both men and women. Numerous studies on the therapeutic effectiveness of nanoparticles against colorectal cancer have been reported. Platinum treatments as well as other medications comprising of nanoparticles have been utilized. Drug resistance restricts the use of platinum medicines, despite their considerable efficacy against a variety of cancers. This review reports clinically licensed platinum medicines (cisplatin, carboplatin, and oxaliplatin) combined with various nanoparticles that have been evaluated for their therapeutic efficacy in the treatment of colorectal cancer, including their mechanism of action, resistance, and limitations.

There are different types of cancer treatments, including surgery, radiotherapy, and chemotherapy. However, the complexity of cancer has resulted in treatment challenges to medicinal scientists and a socio-economic burden to the public health system globally. The pharmacological limitations associated with the current conventional anticancer drugs include lack of specificity, poor bioavailability, toxicity, drug resistance, and poor delivery mechanisms, which make cancer treatment challenging. Thus, the number of cancer cases is escalating rapidly, especially breast and prostate cancer in women and men, respectively. The application of nanoformulations is gaining momentum for treating different cancer types. However, they also exhibit challenges that must be addressed for effective cancer treatment. Nanoliposomes are nanoformulations that are widely explored for cancer treatment with interesting therapeutic outcomes. They have been functionalized with PEG to further improve their therapeutic outcomes. Hence, this review provides an update on PEGylated nanoliposomes loaded with anticancer drugs for the treatment of breast and prostate cancer, focusing on pre-clinical studies published in the last decade (2015 to 2024) to reflect the recent advancements made in the design of PEGylation nanoliposomes. Highlights of the clinically and commercially available PEGylation nanoliposomes are also presented in this review.

Malignant brain tumor is a life-threatening disease with a low survival rate. The therapies available for the treatment of brain tumor is limited by poor uptake via the blood–brain barrier. The challenges with the chemotherapeutics used for the treatment of brain tumors are poor distribution, drug toxicity, and their inability to pass via the blood–brain barrier, etc. Several researchers have investigated the potential of nanomedicines for the treatment of brain cancer. Nanomedicines are designed with nanosize particle sizes with a large surface area and are loaded with bioactive agents via encapsulation, immersion, conjugation, etc. Some nanomedicines have been approved for clinical use. The most crucial part of nanomedicine is that they promote drug delivery across the blood–brain barrier, display excellent specificity, reduce drug toxicity, enhance drug bioavailability, and promote targeted drug release mechanisms. The aforementioned features make them promising therapeutics for brain targeting. This review reports the in vitro and in vivo results of nanomedicines designed for the treatment of brain cancers.

Neurological-related diseases are among the most debilitating and difficult to manage. Many possible pharmacological treatments for neurological diseases struggle to cross the blood–brain barrier (BBB) to achieve concentrations that can produce a therapeutic benefit. This is primarily because of the existence of the BBB, which poses significant hurdles for both therapeutic and diagnostic efforts by restricting the entry of most medications. Nasal-to-brain drug transportation has surfaced as an encouraging approach to tackle the difficulties linked with conventional drug administration techniques for neurological disorders. In response, innovative methods for improving drug delivery focus on breaking down the BBB via physical techniques, including optical and photothermal therapy, electrical stimulation, and acoustic or mechanical stimulation. Nanocarriers represent a promising approach for facilitating nasal systemic and brain delivery of active compounds. Hence, the achievement of therapeutically relevant concentrations of exogenous molecules within the body is significantly contingent upon the nanocarriers’ capability to surpass biological barriers. Polymers in nanocarrier formulations can result in significantly enhanced nose-to-brain drug delivery by protecting drugs from premature biodegradation, increasing permeability, improving mucoadhesion, and targeting specific cells in the brain. Polymeric nanocarriers are frequently functionalized with cell-penetrating peptides to further improve the specificity of the loaded therapeutic molecules. This review focuses on the use of nanocarrier-based therapeutic agents to enhance the efficacy of nose-to-brain delivery systems.