Liposomes are distinguished by their unique structure, represented by the lipid bilayer. This lipid-based vesicle is similar to cellular membranes, has an augmented biocompatibility like other synthetic materials, and has the potential to be a useful drug vehicle, as it is intended to be a nanocarrier [84,85]. The research is focused on their utilization as nanocarriers of drugs with a high toxicity, such as those employed in oncology. Under these circumstances, liposomes can present a great advantage in terms of permitting the transport of specific agents and allowing for a controlled release of the drug within a particular organ [32,63,67]. Another advantage of using liposomes in therapy is that they protect the loaded drug from degradation and prevent undesirable exposure to the environment [86].

Liposomes can be classified according to their size, the number of bilayers, or the preparation method: multilamellar vesicles that consist of several lipid bilayers separated from one another by aqueous spaces, which are heterogenous in size: small unilamellar vesicles comprised of a single bilayer surrounding the entrapped aqueous space, possessing a diameter less than 100 nm; or large unilamellar vesicles composed of a single bilayer surrounding the entrapped aqueous space, with a diameter larger than 100 nm [83,87].

The release of the drug can be deliberately triggered by different techniques, such as ultrasound, light, magnetism, or hyperthermia. Several experts in the field attempted to modify the surface of the liposomes to improve their capability to target different types of cancer and accumulate at the site of the tumors, delivering a higher concentration of the drug [32,88,89,90]. Liposomes can also be employed to alter DNA, anticancer agents, and antibiotics to improve chemotherapy by adding specific molecules to their surface, according to the tumor type or gene delivery, these being the most encouraging tools for cancer gene therapy [91,92,93]. Currently, there are only two products available on the market that can be utilized for ovarian cancer and lymphoblastic leukemia [94].

Regarding liposome usage in lung cancer treatment, a specific and outstanding benefit noticed was the uniform particle size distribution with respect to liposome, operating as drug delivery agents. There are at least a few studies in which the biodistribution of these formulations was indicated as an evidently strong point for choosing them as medication carriers [95].

Dendrimers are a unique class of highly branched macromolecules whose shape and size can be controlled. These polymetric molecules are made up of multiple branched monomers capable of self-organization [29,96]. Structurally, the dendrimers are constituted by three essential regions: a central core, branches, or end groups, and the surface is formed using convergent or divergent step-growth polymerization, starting from monomers [97]. The size of these polymeric nanostructures depends on the number of branching points, which can be controlled and begin from a spherical central core. The cavities shaped inside the core structure and folds of the branches form cages and channels [98]. The free ends of the dendrimer arrangement can be used to attach other molecules, such as liposomes, nanoparticles, carbon nanotubes, anticancer compounds, or radioligands, or they can be transformed into biocompatible compounds with a high bio-permeability and low cytotoxicity [99,100]. Dendrimers present a variety of qualities, such as a surface functionalization capability and monodispersity of size, which make them attractive candidates for gene therapy—due to their ability to enter the cells via endocytosis—or for drug delivery and anticancer therapy, including chemotherapy [101,102]. If we refer to dendrimers as nanocarriers for drug delivery, the specific drug molecules can be quickly included via ligand- or receptor-mediated endocytosis [96].

Dendrimers show many advantages, such as a high drug-loading capacity, nano-size, which is favorable for targeting, and the capability to improve the solubility of poorly soluble anti-neoplastic drugs [103,104]. Nevertheless, their intrinsic toxicity cannot be disregarded—all classes of dendrimers manifest cytotoxic and hemolytic characteristics. This toxicity is dependent on the specific features of dendrimers and is related to the surface end groups [102,105]. To minimize the toxicity, polyethylene glycol can be associated or conjugated, as it can improve the plasma circulation time and tumor accumulation through an enhanced permeability and retention [106]. Different varieties of dendrimers can be utilized for multiple purposes, such as drug-encapsulated dendrimers or dendrimer drug conjugates that boast several benefits over drug-encapsulated systems. These nanocarriers can pass through several delivery barriers using two distinct mechanisms: passive and active targeting [107].

Regarding lung cancer treatment management using dendrimers, several studies have already shown promising outcomes. Doxorubicin (DOX), Cis-diamminodichloridoplatinum (II) (CDDP), and cisplatin (cisPt) are just a few of the efficient anti-tumoral medications tested as loads for dendrimers that are worth mentioning [108].

Polymers can be divided into natural polymers, synthetic polymers, and microbial fermentation polymers, but only natural and synthetic ones can be used for nano delivery. Polymeric nanoparticles are solid, nanosized colloidal particles that consist of a biodegradable polymer that should be biocompatible and non-toxic [109,110,111]. These features are the most important when this nanoparticle is desired for use in drug delivery and gene therapy, as well as other applications. Natural polymers are obtained directly from natural resources, as opposed to synthetic polymers, which are modified or synthesized in the laboratory using different techniques and devices and are frequently used for nanoparticle design and development [32,64]. The most widely used polymer is chitosan, whereas other polymers are extensively used in nanoparticle synthesis, including dextran, albumin, heparin, gelatin, or collagen. Natural polymeric nanoparticles are biocompatible and non-toxic; however, when this type of nanoparticle is delivered across different biological membranes, issues such as on-site stability and a local variation in pH levels may sometimes limit their usefulness [64,65,66].

Synthetic polymers, such as polylactic acid, polyglycolic acid, and polyhydroxybutyrate, or other families of polymers are usually employed and suitable for drug delivery due to their individual characteristics, such as biocompatibility and biodegradability [112,113]. Synthetic polymeric nanoparticles present a particularly excellent result in terms of the release of drugs within the lungs in a controlled manner. They are a good candidate for oral, intravenous, or combined administering because of their advantages: biocompatibility and biodegradability, inferior toxicity, and low cost of production in large quantities using multiple methods [32,111]. Based on their structural organization, polymeric nanoparticles can be divided into nanocapsules and nanospheres. There have been numerous attempts to deliver a variety of anticancer drugs using polymeric nanoparticles, considering the physicochemical properties of polymers, their degradation, and the accurate and controllable drug release rate [32,114]. Moreover, it is also possible to synthesize polymeric nanoparticles with specific sizes, shapes, and surface modifications, offering a heightened precision in delivering a particular drug. All these developments have established a new direction in cancer treatment [115,116]. There is a large number of polymeric nanoparticles that have already been used in different phases of clinical trials—Abraxane has been approved by the Food and Drug Administration (FDA) for the treatment of different types of malignancies, such as breast cancer, NSCLC, and pancreatic cancer, or BIND-014, which is the first targeted polymeric nanoparticle utilized for the treatment of metastatic melanoma and squamous cell carcinoma [49,117,118].

Regarding nanocapsules, the drug is dissolved or dispersed in a liquid core of oil or water, which is encapsulated by a solid polymeric membrane, or in the case of the nanospheres, the drug is dispersed/entrapped in the polymer matrix. In both cases, the absorption or chemical conjugation of the drug on the surface is possible. As mentioned above, among the most important characteristics for polymers are biocompatibility and biodegradability; being biodegradable, these polymers can be degraded into individual monomers inside the body and removed from the body through metabolic pathways [32,40,48].

Micelles are nanosized, spherical colloidal particles, and lipid nanostructures consist of a hydrophobic core and a hydrophilic shell. In an aqueous environment, micelles hide their hydrophobic groups inside the structure and expose hydrophilic groups, whereas inside environments rich in lipids, these nanostructures are organized in the opposite way [119,120,121]. Micelles represent another variant of nanosystem that can be used to treat and diagnose multiple types of cancer and deliver various anticancer agents. By producing different variations of these nanosystems, it will be possible to monitor the pathways of interest and to estimate the therapeutic response [32,122,123]. Micelles are an innovative drug delivery system due to their stability in physiological conditions, high and versatile loading capacity, high accumulation of drugs at the target site, and their possibility of functionalizing the end group [38]. Medications can be entrapped within the hydrophobic core or linked covalently to the shell of these nanosystems. Micelles are stable and have a prolonged circulation time within the bloodstream, evading host defenses [124,125]. The nanocarriers’ ability to circumvent passive targeting via the fenestrated vasculature of tumors can be improved by covalent conjugation with the polyethylene glycol of the micelles’ surface. In an aqueous environment, the hydrophobic core of the micelles can solubilize water-insoluble drugs, and the shell of the micelles can adsorb polar molecules [38,39]. In contrast, drugs with an intermediate polarity can be distributed along with the surfactant molecules in intermediate positions. Many micelles that contain anticancer drugs are under clinical trials, and only one of these nanosystems is approved for treating breast cancer patients [124]. Specifically, with regard to cancer lung management, one of the greatest advantages posed by micelles are the facile methods used for modifying their surfaces and the great specificity shown by these adjusted particles for the lung tumor environment [126]. Docetaxel (DTXL), Paclitaxel, and cisPt in combination with etoposide (ETO) are some of the most important anti-tumoral drugs for which micelles served as nanocarriers in lung cancer treatment studies [127].

Gold nanoparticles are intensely studied in connection with lung cancer therapy and diagnosis. In combination with Methotrexate, gold nanoparticles produce a cytotoxic effect in lung carcinomas [95]. A high reactivity characterizes the surface of gold nanoparticles. Due to this property, the surface of these nanoparticles can be easily modified or conjugated with functional biomolecules or other materials [35,134]. Gold nanoparticles can be encapsulated in liposomes, conjugated with nucleotides, coated with different polymer layers, or utilized as the core for dendrimers [83]. As mentioned above, nanoparticles are used for the targeted delivery of gene molecules. Of interest is siRNA, which is less stable, and enzymes can be attached to the microenvironment. Nanoparticles have the possibility of altering the fate of siRNA upon in vivo administration [135,136,137]. The advantages of nanoparticles favor siRNA delivery across biological barriers, which can be achieved using different methods: siRNA can be conjugated on the surface of nanoparticles via a gold–thiol bond or electrostatic interactions, or it can adhere to the surface of the nanoparticles using polymer layers [138,139]. Gold nanoparticles are already used as an siRNA carrier system. The most important properties of gold are that it is non-toxic and can form fine nanoparticles, which can be functionalized for efficient gene delivery [34]. Using electrostatic or covalent methods, siRNA can be bound on the surface of the metal. Polyvalent molecules of siRNA can be attached to the surface of gold nanoparticles via thiol groups. These kinds of particles are characterized by a higher stability [139]. If a polyethyleneimine coating is added to the gold nanoparticle, this could render it a perfect siRNA delivery system. The interaction between polyethyleneimine-capped gold nanoparticles and siRNA is electrostatic [140,141]. It is worth mentioning that gold nanoparticles with cationic polymer modifications are excellent gene delivery systems. Gold nanoparticles can become stimuli-responsive, and in this way, siRNA delivery is very efficient [142]. Additionally, researchers have also developed a system represented by a gold nanoparticle-based sensor capable of detecting lung cancer by analyzing the exhaled breath of the patient. Gold nanoparticles were tested as sensors and are capable of detecting lung cancer due to their histology. As sensors, they were capable of distinguishing between the subtypes of lung cancer [139,140,141,142,143,144,145].

Concerning pulmonary cancer management, gold nanoparticles have at least three important advantages. Firstly, gold nanomaterials can be used as a diagnostic tool, offering important advantages in comparison with traditional organic dyes, such as a minimal toxicity and insignificant quenching [146]. Finally, gold nanomaterials exhibit therapeutic effects per se due to their implications and use in Photodynamic therapies (PDTs), which have been studied extensively in the chapter on the therapeutic effects of nanomaterials in the current article [147].

Carbon nanotubes are nanosized, hollow, and graphite sheets that are rolled up into a tubular form and belong to the family of fullerenes. These structures are called single-walled carbon nanotubes, if characterized by the presence of a single graphene sheet, or multi-walled carbon nanotubes, if they are formed from several concentric graphene sheets [148]. The diameter of single-walled nanotubes range between 0.5–3 nm, and the length can vary between 20–1000 nm, and as for multi-walled carbon nanotubes, the dimensions are 1.5–100 nm and 1–50 microns, respectively. Single-walled and multi-walled carbon nanotubes can be utilized as nanocarriers for specific drug delivery due to their specific physicochemical and biological characteristics [148,149,150]. Some of these characteristics may include a nanoneedle shape, hollow monolithic structure, high mechanical strength, high electrical and thermal conductivities, and also the ability to make surface adjustments [66]. The main disadvantage of carbon nanotubes as a drug nanocarrier is the poor water solubility and toxicity. The functionalization of carbon nanotubes is an essential key parameter in reducing the toxicity and maximizing the bioavailability of anticancer drugs, and carbon nanotubes are becoming an ideal nanocarrier for cancer therapy [66,151]. These nanostructures were intensively studied in recent years as a nanocarrier for anticancer drug delivery. There are many applications in which carbon nanotubes are very useful, such as gene delivery. The capacity of carbon nanotubes to transport DNA across the cell membrane is widely used in studies that involve gene therapy or gene silencing. A highly selective therapy is needed for cancer therapy, wherein tumor cells will be selectively modulated, so in this case, gene silencing may be performed using siRNA. However, delivering siRNA to specific cells is very problematic, given the instability of siRNA and their low uptake efficiency [21,47,48,49,60,69].

On the other hand, a crucial advantage of using these nano-sized materials in lung cancer treatment is their ability to enhance the effectiveness of chemotherapy, just by their plain administration in combination with such conventional anti-tumoral drugs. In addition, it was shown that using carbon nanotubes may prove to be effective in treating multidrug-resistant and/or radioresistant tumors, a fact that represents another important benefit of these materials [54]. Several studies involving Gemcitabine, Curcumin, Paclitaxel, and DOX carried by carbon nanotubes demonstrated the great versatility of these inorganic materials in the context of their use as drug nanocarriers [152].