Time-Dependent Controlled Release of Ferulic Acid from Surface-Modified Hollow Nanoporous Silica Particles

Release of ferulic acid from surface-functionalized hollow nanoporous silica particles (HNSPs) was investigated in deionized water (DI water) and in ethanol. The host material, an HNSP, was synthesized in the presence of polymer and surfactant templates, and the pore as well as the surface were modified with either pentyltriethoxysilane (PTS) or octyltriethoxysilane (OTS) through silane coupling reactions. The inner hollow space occupied a volume of ~45% of the whole HNSP with a 2.54 nm pore channel in the wall. The pore size was estimated to decrease to 1.5 nm and 0.5 nm via the PTS and OTS functionalization, respectively. The encapsulation efficiencies of the HNSP (25 wt%), PTS-functionalized HNSP (PTS-HNSP, 22 wt%) and OTS-functionalized HNSP (OST-HNSP, 25 wt%) toward ferulic acid were similar, while the %release in DI water and ethanol varied following HNSP > PTS-HNSP > OTS-HNSP. Release kinetic analyses with Korsmeyer-Peppas fitting suggested a trade-off relationship between the solvent's ability to access the HNSP and the affinity of ferulic acid to the surface, allowing us to understand the solvent's controlled release rate and mechanism.

Fabrication of curcumin-loaded magnetic PEGylated-PLGA nanocarriers tagged with GRGDS peptide for improving anticancer activity

Carrier-mediated drug delivery systems are highly promising as a treatment option for the targeted delivery of potent cytotoxic drugs with increased efficacy and safety. Considering that poly (lactic-co-glycolic acid) (PLGA) and polyethylene glycol (PEG) polymers each provide certain advantages for biological purposes, PEGylated-PLGA nanoparticles have emerged as a leading candidate among other alternatives. Furthermore, these nanoparticles can be modified with the specific short peptide sequences such as glycine-arginine-glycine-aspartic acid‑serine (GRGDS), which selectively binds to integrins overexpressed in most cancer cells, allowing for targeted delivery. Here, we reported the details in fabrication and characterization of magnetic PEGylated-PLGA nanoparticles functionalized with GRGDS peptide. In addition, superparamagnetic iron oxide nanoparticles (SPIONs) and the natural pharmaceutical compound curcumin (Cur) were loaded into these polymeric nanoparticles to assess their anticancer activity potential. Overall, this study provides comprehensive methodologies, including all synthesis procedures, challenges, and useful suggestions for peptide-conjugated polymeric nanoparticles that may be used for cellular targeting and therapeutic applications.•Step by step fabrication protocol for the Cur loaded magnetic PEGylated-PLGA nanoparticles was presented.•Validation of the fabrication and the GRGDS conjugation to the nanoparticles were shown via detailed characterization studies.•The cytotoxic effect of the Cur-loaded and GRGDS-tagged magnetic nanoparticles was tested on T98G glioblastoma cell line as a preliminary in vitro study.

Development of Triple-Negative Breast Cancer-Targeted Liposomes with MUC16 Binding Peptide Ligand in Triple-Negative Breast Cancer Cells

Triple-negative breast cancer (TNBC) is a highly malignant tumor that does not express the estrogen receptor (ER), progesterone receptor (PR), or human epidermal growth factor receptor 2 (HER-2). As molecular approaches to these targets have limited clinical utility in TNBC, novel strategies for the treatment of TNBC are urgently needed. MUC16 (Mucin-16) is a glycoprotein involved in cell proliferation and apoptosis and is overexpressed in breast cancer. To develop a clinically available strategy for TNBC treatment, we synthesized a MUC16 targeted peptide (EVQ)-grafted lipid derivative, EVQ-(SG)₅-lipid, and prepared EVQ-(SG)₅/PEGylated liposomes of 100 nm by size and a slightly negative ζ-potential value. Thus, we aimed at investigating the association between EVQ-(SG)₅/PEGylated and TNBC cell lines by interacting with MUC16 using an in vitro model. In addition, we aimed at exploring the intracellular distribution and cellular uptake pathway of EVQ-(SG)₅/PEGylated liposomes as novel drug delivery carriers for TNBC.

Photochemical Consideration in the Interactions between Blood Proteins and Layered Inorganic Materials

Interactions between layered double hydroxide (LDH) nanomaterials and plasma proteins according to their particle size and surface charge were evaluated. The LDHs with different particle size (150, 350 and 2000 nm) were prepared by adjusting hydrothermal treatment and urea hydrolysis and subsequent organic coating with citrate, malite and serite was applied to control the surface charge (ζ-potential: −15, 6 and 36 mV). Adsorption isotherms and Stern–Volmer plots for fluorescence quenching indicated that the human blood plasma had weak interactions toward all the types of LDHs. The adsorption isotherms did not show significant differences in the size and surface charges, while the fluorescence quenching ratio increased with the increase in the surface charge, implying that electrostatic interaction played a major role in their interactions. The fluorescence quenching of three types of plasma proteins (human serum albumin, γ-globulin and fibrinogen) by the surface charge-controlled LDHs suggested that the proteins adsorbed on the LDHs with a single layer and additional proteins were weakly adsorbed to surround the LDHs with adsorbed proteins. It was concluded that the LDH nanomaterials are fairly compatible for blood components due to the protein corona while the electrostatic interaction can affect their interaction with the proteins.

Design, Synthesis and In Vivo Fluorescence Imaging Study of a Cytochrome P450 1B1 Targeted NIR Probe Containing a Chelator Moiety

Cytochrome P450 (CYP) 1B1 has been found to be overexpressed specifically in tumor tissues at early stage, which makes it a potential cancer biomarker for molecular imaging of cancer. Multimodal imaging combines different imaging modalities and offers more comprehensive information. Thus, imaging probes bearing more than one kind of signal fragment have been extensively explored and displayed great promise. Herein, we developed a near infrared (NIR) probe with a chelator moiety targeting CYP1B1 by conjugating α-naphthoflavone (ANF) derivatives with both a NIR dye and a chelator for potential application in bimodal imaging. Enzymatic inhibitory studies demonstrated inhibitory activity against CYP1B1 and selectivity among CYP1 were successfully retained after chemical modification. Cell-based saturation study indicated nanomolar range binding affinity between the probe and CYP1B1 overexpressed cancer cells. In vitro competitive binding assay monitored by confocal microscopy revealed that the probe could specifically accumulate in tumor cells. In vivo and ex vivo imaging studies demonstrated the probe could effectively lighten up the tumor tissues as early as 2 hours post injection. Besides, the fluorescence was significantly blocked by co-injection of CYP1B1 inhibitor, which indicated the probe accumulation in tumor sites was due to specific binding towards CYP1B1.

Development and Biochemical Characterization of Self-Immolative Linker Containing GnRH-III-Drug Conjugates

The human gonadotropin releasing hormone (GnRH-I) and its sea lamprey analogue GnRH-III specifically bind to GnRH receptors on cancer cells and can be used as targeting moieties for targeted tumor therapy. Considering that the selective release of drugs in cancer cells is of high relevance, we were encouraged to develop cleavable, self-immolative GnRH-III-drug conjugates which consist of a p-aminobenzyloxycarbonlyl (PABC) spacer between a cathepsin B-cleavable dipeptide (Val-Ala, Val-Cit) and the classical anticancer drugs daunorubicin (Dau) and paclitaxel (PTX). Alongside these compounds, non-cleavable GnRH-III-drug conjugates were also synthesized, and all compounds were analyzed for their antiproliferative activity. The cleavable GnRH-III bioconjugates revealed a growth inhibitory effect on GnRH receptor-expressing A2780 ovarian cancer cells, while their activity was reduced on Panc-1 pancreatic cancer cells exhibiting a lower GnRH receptor level. Moreover, the antiproliferative activity of the non-cleavable counterparts was strongly reduced. Additionally, the efficient cleavage of the Val-Ala linker and the subsequent release of the drugs could be verified by lysosomal degradation studies, while radioligand binding studies ensured that the GnRH-III-drug conjugates bound to the GnRH receptor with high affinity. Our results underline the high value of GnRH-III-based homing devices and the application of cathepsin B-cleavable linker systems for the development of small molecule drug conjugates (SMDCs).

Therapeutic peptides: current applications and future directions

Peptide drug development has made great progress in the last decade thanks to new production, modification, and analytic technologies. Peptides have been produced and modified using both chemical and biological methods, together with novel design and delivery strategies, which have helped to overcome the inherent drawbacks of peptides and have allowed the continued advancement of this field. A wide variety of natural and modified peptides have been obtained and studied, covering multiple therapeutic areas. This review summarizes the efforts and achievements in peptide drug discovery, production, and modification, and their current applications. We also discuss the value and challenges associated with future developments in therapeutic peptides.

Peptide Multimerization as Leads for Therapeutic Development

Multimerization of peptide structures has been a logical evolution in their development as potential therapeutic molecules. The multivalent properties of these assemblies have attracted much attention from researchers in the past and the development of more complex branching dendrimeric structures, with a wide array of biocompatible building blocks is revealing previously unseen properties and activities. These branching multimer and dendrimer structures can induce greater effect on cellular targets than monomeric forms and act as potent antimicrobials, potential vaccine alternatives and promising candidates in biomedical imaging and drug delivery applications. This review aims to outline the chemical synthetic innovations for the development of these highly complex structures and highlight the extensive capabilities of these molecules to rival those of natural biomolecules.

Synthesis and Evaluation of High Functionality and Quality Cell-penetrating Peptide Conjugated Lipid for Octaarginine Modified PEGylated Liposomes In U251 and U87 Glioma Cells

The use of peptide ligand modified PEGylated liposomes has been widely investigated for tumor targeting. Peptides are mainly inserted in the liposomal lipid bilayer using PEG_2K-lipid spacer (Peptide-PEG_2K-DSPE). However, a lower cellular uptake from longer nonlinear PEG_2K spacer was reported, we here synthesized a high functionality and quality (HFQ) lipid with a short, linear serine-glycine repeated peptide [(SG)₅] spacer. The objective of the current study is to develop novel octaarginine (R₈) peptide-HFQ lipid grafted PEGylated liposomes for glioma cells targeting. In vitro liposomes characterization showed that the mean particle size of all liposomal formulations was in the nano-scale range < 120 nm, with a small PDI value (i.e. ∼0.2) and had a spherical shape under Transmission Electron Microscope, indicating a homogenous particle size distribution. The flow cytometry in vitro cellular association data with U251 MG and U87 cells revealed that 1.5% R₈-(SG)₅-lipid-PEGylated liposomes exhibited significantly higher cellular association of ∼15.87 and 7.59-fold than the conventional R₈-PEG_2K-lipid-PEGylated liposomes (10.4 and 6.19-fold), respectively, relative to the unmodified PEGylated liposomes. Moreover, intracellular distribution studies using confocal laser scanning microscopy (CLSM) corroborated the results of the in vitro cell association. The use of ligand-HFQ-lipid liposomes could be a potential alternative to ligand-PEG_2K-lipid-modified liposomes as a drug delivery system for tumor targeting.

Therapeutic peptides for chemotherapy: Trends and challenges for advanced delivery systems

The past decades witnessed an increasing interest in peptides as clinical therapeutics. Rightfully considered as a potential alternative for small molecule therapy, these remarkable pharmaceuticals can be structurally fine-tuned to impact properties such as high target affinity, selectivity, low immunogenicity along with satisfactory tissue penetration. Although physicochemical and pharmacokinetic challenges have mitigated, to some extent, the clinical applications of therapeutic peptides, their potential impact on modern healthcare remains encouraging. According to recent reports, there are more than 400 peptides under clinical trials and 60 were already approved for clinical use. As the demand for efficient and safer therapy became high, especially for cancers, peptides have shown some exciting developments not only due to their potent antiproliferative action but also when used as adjuvant therapies, either to decrease side effects with tumor-targeted therapy or to enhance the activity of anticancer drugs via transbarrier delivery. The first part of the present review gives an insight into challenges related to peptide product development. Both molecular and formulation approaches intended to optimize peptide's pharmaceutical properties are covered, and some of their current issues are highlighted. The second part offers a comprehensive overview of the emerging applications of therapeutic peptides in chemotherapy from bioconjugates to nanovectorized therapeutics.

Synthesis and physicochemical evaluation of fluorinated lipopeptide precursors of ligands for microbubble targeting

Ligand-targeted microbubbles are focusing interest for molecular imaging and delivery of chemotherapeutics. Lipid-peptide conjugates (lipopeptides) that feature alternating serine-glycine (SG) n segments rather than classical poly(oxyethylene) linkers between the lipid polar head and a targeting ligand were proposed for the liposome-mediated, selective delivery of anticancer drugs. Here, we report the synthesis of perfluoroalkylated lipopeptides (F-lipopeptides) bearing two hydrophobic chains (C n F2 n +1, n = 6, 7, 8, 1-3) grafted through a lysine moiety on a hydrophilic chain composed of a lysine-serine-serine (KSS) sequence followed by 5 SG sequences. These F-lipopeptides are precursors of targeting lipopeptide conjugates. A hydrocarbon counterpart with a C10H21 chain (4) was synthesized for comparison. The capacity for the F-lipopeptides to spontaneously adsorb at the air/water interface and form monolayers when combined with dipalmitoylphosphatidylcholine (DPPC) was investigated. The F-lipopeptides 1-3 demonstrated a markedly enhanced tendency to form monolayers at the air/water interface, with equilibrium surface pressures reaching ≈7-10 mN m-1 versus less than 1 mN m-1 only for their hydrocarbon analog 4. The F-lipopeptides penetrate in the DPPC monolayers in both liquid expanded (LE) and liquid condensed (LC) phases without interfacial film destabilization. By contrast, 4 provokes delipidation of the interfacial film. The incorporation of the F-lipopeptides 1-3 in microbubbles with a shell of DPPC and dipalmitoylphosphatidylethanolamine-PEG2000 decreased their mean diameter and increased their stability, the best results being obtained for the C8F17-bearing lipopeptide 3. By contrast, the hydrocarbon lipopeptide led to microbubbles with a larger mean diameter and a significantly lower stability.

Co-delivery Systems of Multiple Drugs Using Nanotechnology for Future Cancer Therapy

Cancer treatments have improved significantly during the last decade but are not yet satisfactory. Combination therapy is often administered to improve efficacy and safety. Drug delivery systems can also improve efficacy and safety. To control the spatiotemporal distribution of drugs, nanotechnology involving liposomes, solid lipid nanoparticles, and polymeric micelles has been developed. Co-delivery systems of multiple drugs are a promising approach to combat cancer. Synergistic effects and reduced side effects are expected from the use of co-delivery systems. In this review, we summarize various co-delivery systems for multiple drugs, including small-molecule drugs, nucleic acids, genes, and proteins. Co-delivery of drugs with different properties is relatively difficult, but some researchers have succeeded in developing such co-delivery systems. Environment-responsive carrier designs can control the release of cargos. Although their preparation is more complicated than that of mono-delivery systems, co-delivery systems can simplify clinical procedures and improve patient QOL.

Recent Advances in Peptide-Based Approaches for Cancer Treatment

BACKGROUND

Peptide-based pharmaceuticals have recently experienced a renaissance due to their ability to fill the gap between the two main classes of available drugs, small molecules and biologics. Peptides combine the high potency and selectivity typical of large proteins with some of the characteristic advantages of small molecules such as synthetic accessibility, stability and the potential of oral bioavailability.

METHODS

In the present manuscript we review the recent literature on selected peptide-based approaches for cancer treatment, emphasizing recent advances, advantages and challenges of each strategy.

RESULTS

One of the applications in which peptide-based approaches have grown rapidly is cancer therapy, with a focus on new and established targets. We describe, with selected examples, some of the novel peptide-based methods for cancer treatment that have been developed in the last few years, ranging from naturally-occurring and modified peptides to peptidedrug conjugates, peptide nanomaterials and peptide-based vaccines.

CONCLUSION

This review brings out the emerging role of peptide-based strategies in oncology research, critically analyzing the advantages and limitations of these approaches and the potential for their development as effective anti-cancer therapies.

Development of the Tumor-Specific Antigen-Derived Synthetic Peptides as Potential Candidates for Targeting Breast and Other Possible Human Carcinomas

The human epidermal growth factor receptor 2 (HER2) represents one of the most studied tumor-associated antigens for cancer immunotherapy. The receptors for HER2 are overexpressed in various human cancers, such as breast and ovarian cancer. The relatively low expression of this antigen on normal tissues makes it a clinically useful molecular target for tumor imaging and targeted therapy. HER2 overexpression is correlated with aggressive tumor behavior and poor clinical outcomes. Thus, HER2 has become an important prognostic and predictive factor, as well as a potential molecular target. Due to the heterogeneity of breast cancer and possible discordance in HER2 status between primary tumors and distant metastases, assessment of HER2 expression by noninvasive imaging is important. Molecular imaging of HER2 expression may provide essential prognostic and predictive information concerning disseminated cancer and aid in the selection of an optimal therapy. Another tumor-specific antigen is MUC1, which is silent on normal tissues, but overexpressed in almost all human epithelial cell cancers, including >90% of human breast, ovarian, pancreatic, colorectal, lung, prostate, and gastric cancers and is a promising tumor antigen with diagnostic as well as the therapeutic potential of cancer. Radiolabeled small peptide ligands are attractive as probes for molecular imaging, as they reach and bind the target receptor efficiently and clear from blood and non-target organs faster than bulky antibodies. In this study, HER2 and MUC1-based peptides were synthesized and preclinically evaluated in an effort to develop peptide-based SPECT radiopharmaceuticals derived from tumor-associated antigens for the detection of breast cancer. Our findings demonstrate that the tumor antigen peptides radiolabeled efficiently with ^99mTc and showed high metabolic stability in human plasma in vitro. The data from breast tumor cell binding confirmed the high affinity (in low nanomolar range) towards respective breast cancer cell lines. In healthy mice, ^99mTc-labeled peptides displayed favorable pharmacokinetics, with high excretion by the renal system. In tumor xenografts nude mice models, good uptake by the SKBR3, MCF7, and T47D tumors were found, with good tumor-to-blood and tumor to muscle ratios. Additionally, tumor lesions can be seen in γ-camera imaging. Our data suggest that based on its ability to detect HER2- and MUC1-positive breast cancer cells in vivo, ^99mTc-HER2 and ^99mTc-MUC1-targeted peptides may be promising tumor imaging probes and warrant further investigation.

Sequence modification of heptapeptide selected by phage display as homing device for HT-29 colon cancer cells to improve the anti-tumour activity of drug delivery systems

Development of peptide-based conjugates for targeted tumour therapy is a current research topic providing new possibilities in cancer treatment. In this study, VHLGYAT heptapeptide selected by phage display technique for HT-29 human colon cancer was investigated as homing peptide for drug delivery. Daunomycin was conjugated to the N-terminus of the peptide directly or through Cathepsin B cleavable spacers. Conjugates showed moderate in vitro cytostatic effect. Therefore, sequence modifications were performed by Ala-scan and positional scanning resulting in conjugates with much higher bioactivity. Conjugates in which Gly was replaced by amino acids with bulky apolaric side chains provided the best efficacy. The influence of the cellular uptake, stability and drug release on the anti-tumour activity was investigated. It was found that mainly the difference in the cellular uptake of the conjugates generated the distinct effect on cell viability. One of the most efficient conjugate Dau = Aoa-LRRY-VHLFYAT-NH₂ showed tumour growth inhibition on orthotopically developed HT-29 colon cancer in mice with negligible toxic side effect compared to the free drug. We also indicate that this sequence is not specific to HT-29 cells, but it has a remarkable effect on many other cancer cells. Nevertheless, the Phe-containing conjugate was more active in all cases compared to the conjugate with the parent sequence. The literature data suggested that this sequence is highly overlapped with peptides that recognize Hsp70 membrane bound protein overexpressed in many types of tumours.

Enhanced In Vitro Antitumor Activity of GnRH-III-Daunorubicin Bioconjugates Influenced by Sequence Modification

Receptors for gonadotropin releasing hormone (GnRH) are highly expressed in various human cancers including breast, ovarian, endometrial, prostate and colorectal cancer. Ligands like human GnRH-I or the sea lamprey analogue GnRH-III represent a promising approach for the development of efficient drug delivery systems for targeted tumor therapy. Here, we report on the synthesis and cytostatic effect of 14 oxime bond-linked daunorubicin GnRH-III conjugates containing a variety of unnatural amino acids within the peptide sequence. All compounds demonstrated a reduced cell viability in vitro on estrogen receptor α (ERα) positive and ERα negative cancer cells. The best candidate revealed an increased cancer cell growth inhibitory effect compared to our lead-compound GnRH-III-[⁴Lys(Bu),⁸Lys(Dau=Aoa)]. Flow cytometry and fluorescence microscopy studies showed that the cellular uptake of the novel conjugate is substantially improved leading to an accelerated delivery of the drug to its site of action. However, the release of the active drug-metabolite by lysosomal enzymes was not negatively affected by amino acid substitution, while the compound provided a high stability in human blood plasma. Receptor binding studies were carried out to ensure a high binding affinity of the new compound for the GnRH-receptor. It was demonstrated that GnRH-III-[²ΔHis,³d-Tic,⁴Lys(Bu),⁸Lys(Dau=Aoa)] is a highly potent and promising anticancer drug delivery system for targeted tumor therapy.

Development of High-Functionality and -Quality Lipids with RGD Peptide Ligands: Application for PEGylated Liposomes and Analysis of Intratumoral Distribution in a Murine Colon Cancer Model

High-functionality and -quality (HFQ) lipids have a discrete molecular weight and good water dispersibility and can be produced by solid-phase peptide synthesis. Therefore, HFQ lipids are a promising material for the preparation of ligand-grafted PEGylated liposomes. Recently, we have reported serine-glycine repeated peptides ((SG) _n) as a spacer of HFQ lipids and to substitute a conventional PEG spacer. We demonstrated the advantage of using (SG) _n spacers for peptide ligand presentation on the liposomal surface in vitro; however, the use of (SG) _n spacers in ligand-grafted PEGylated liposomes in vivo has not been validated. The aim of this study was to validate the in vivo targeting ability of HFQ lipid-grafted PEGylated liposomes. We synthesized lipids containing GRGDS (RGD-(SG) _n-lipid) to target integrin α_vβ₃ and prepared RGD-(SG) _n/PEGylated liposomes. Subsequently, their cellular uptake characteristics in murine colon carcinoma (Colon-26) cells were evaluated. Two-color imaging of liposomes and tumor blood vessels following tissue clearing was performed to examine the spatial intratumoral distribution of liposomes. RGD-(SG)₅/PEGylated liposomes were selectively associated with the cells in vitro. In vivo analysis of intratumoral distribution following tissue clearing revealed the superior targeting ability of RGD-(SG)₅/PEGylated liposomes compared with that of conventional RGD-PEG₂₀₀₀/PEGylated liposomes for both tumor tissues and tumor blood vessels. We successfully synthesized RGD-HFQ lipids to prepare RGD-grafted PEGylated liposomes for the efficient targeting of integrin α_vβ₃-expressing cells. To the best of our knowledge, this is the first report of the intratumoral distribution of ligand-grafted PEGylated liposomes by two-color imaging following tissue clearing.

In Vivo Molecular Imaging for Biomedical Analysis and Therapies

In vivo molecular imaging is a powerful tool to analyze the human body. Precision medicine is receiving high attention these days, and molecular imaging plays an important role as companion diagnostics in precision medicine. Nuclear imaging with PET or SPECT and optical imaging technologies are used for in vivo molecular imaging. Nuclear imaging is superior for quantitative imaging, and whole-body analysis is possible even for humans. Optical imaging is superior due to its ease of use, and highly targeted specific imaging is possible with activatable agents. However, with optical imaging using fluorescence, it is difficult to obtain a signal from deep tissue and quantitation is difficult due to the attenuation and scattering of the fluorescent signal. Recently, to overcome these issues, optoacoustic imaging has been used in in vivo imaging. In this article, we review in vivo molecular imaging with nuclear and optical imaging and discuss their utility for precision medicine.

Synthesis of high functionality and quality mannose-grafted lipids to produce macrophage-targeted liposomes

The mannose receptor, which is responsible for tumor invasion, proliferation, and metastasis in the tumor microenvironment, is overexpressed in tumor-associated macrophages. Mannose is commonly applied to PEGylated liposomes in macrophage-targeted cancer therapy. To develop a high functionality and quality (HFQ) lipid for macrophage-targeted liposomes, we designed a novel mannosylated lipid with improved mannose receptor binding affinity using serine-glycine repeats (SG)_n. We synthesized Man(S)-(SG)₅-SSK-K(Pal)₂ using only a fluorenylmethyloxycarbonyl (Fmoc) protecting group solid-phase peptide synthesis method, which produced a high-quality lipid at a moderately good yield. We then prepared Man-(SG)₅/PEGylated liposomes using a post-insertion technique to insert Man(S)-(SG)₅-SSK-K(Pal)₂ into the PEGylated liposomes. In vitro cell investigations revealed that the Man-(SG)₅/PEGylated liposomes effectively associated with mouse peritoneal macrophages by interacting with the mannose receptors. The results suggest that we produced a novel high-quality, highly functional mannosylated lipid that is suitable for clinical drug delivery applications.

Surface Functionalization and Targeting Strategies of Liposomes in Solid Tumor Therapy: A Review

Surface functionalization of liposomes can play a key role in overcoming the current limitations of nanocarriers to treat solid tumors, i.e., biological barriers and physiological factors. The phospholipid vesicles (liposomes) containing anticancer agents produce fewer side effects than non-liposomal anticancer formulations, and can effectively target the solid tumors. This article reviews information about the strategies for targeting of liposomes to solid tumors along with the possible targets in cancer cells, i.e., extracellular and intracellular targets and targets in tumor microenvironment or vasculature. Targeting ligands for functionalization of liposomes with relevant surface engineering techniques have been described. Stimuli strategies for enhanced delivery of anticancer agents at requisite location using stimuli-responsive functionalized liposomes have been discussed. Recent approaches for enhanced delivery of anticancer agents at tumor site with relevant surface functionalization techniques have been reviewed. Finally, current challenges of functionalized liposomes and future perspective of smart functionalized liposomes have been discussed.