Analytical methods for investigating in vivo fate of nanoliposomes:A review

Nanoliposomes are considered to be the most successful nanoparticle drug delivery system, but their fate in vivo has not been fully understood due to lack of reliable bioanalytical methods, which seriously limits the development of liposomal drugs. Hence, an overview of currently used bioanalytical methods is imperative to lay the groundwork for the need of developing a bioanalytical method for liposome measurements in vivo. Currently, major analytical methods for nanoliposomes measurement in vivo include fluorescence labeling, radiolabeling, magnetic resonance imaging（MRI）, mass spectrometry and computed tomography. In this review, these bioanalytical methods are summarized, and the advantages and disadvantages of each are discussed. We provide insights into the applicability and limitations of these analytical methods in the application of nanoliposomes measurement in vivo, and highlight the recent development of instrumental analysis techniques. The review is devoted to providing a comprehensive overview of the investigation of nanoliposomes design and associated fate in vivo, promoting the development of bioanalytical techniques for nanoliposomes measurement, and understanding the pharmacokinetic behavior, effectiveness and potential toxicity of nanoliposomes in vivo.

Effect of physicochemical properties on in vivo fate of nanoparticle-based cancer immunotherapies

Current advances of immunotherapy have greatly changed the way of cancer treatment.At the same time,a great number of nanoparticle-based cancer immunotherapies(NBCIs)have also been explored to elicit potent immune responses against tumors.However,few NBCIs are nearly in the clinical trial which is mainly ascribed to a lack understanding of in vivo fate of nanoparticles(NPs)for cancer immunotherapy.NPs for cancer immunotherapy mainly target the immune organs or immune cells to enable effcient antitumor immune responses.The physicochemical properties of NPs including size,shape,elasticity and surface properties directly affect their interaction with immune systems as well as their in vivo fate and therapeutic effect.Hence,systematic analysis of the physicochemical properties and their effect on in vivo fate is urgently needed.In this review,we frst recapitulate the fundamentals for the in vivo fate of NBCIs including physio-anatomical features of lymphatic system and strategies to modulate immune responses.Moreover,we highlight the effect of physicochemical properties on their in vivo fate including lymph nodes(LNs)drainage,cellular uptake and intracellular transfer.Challenges and opportunities for rational design of NPs for cancer immunotherapy are also discussed in detail.

Insight into the in vivo fate of intravenous herpetrione amorphous nanosuspensions by aggregation-caused quenching probes

Intravenous nanosuspensions are attracted growing attention as a viable strategy for development of intravenous formulations of poorly water-soluble drugs.However,only few information about the biological fate of intravenous nanosuspensions is currently known,especially amorphous nanosuspensions are not reported yet.In this study,the in vivo fate of herpetrione(HPE)amorphous nanosuspensions following intravenous administration was explored by using an aggregation-caused quenching(ACQ)probe and HPLC methods.The ACQ probe is physically embedded into HPE nanoparticles via anti-solvent method to form HPE hybrid nanosuspensions(HPE-HNSs)for bioimaging.HPE-HNSs emit strong and stable fluorescence,but fluorescence quenches immediately upon the dissolution of HPE-HNSs,confirming the selfdiscrimination of HPE-HNSs.Following intravenous administration of HPE-HNSs,integral HPE-HNSs and HPE show similar degradation and biodistribution,with rapid clearance from blood circulation and obvious accumulation in liver and lung.Due to the slower dissolution and enhanced recognition by reticuloendothelial system,450 nm HPE-HNSs accumulate more in liver,lung and spleen than that of 200 nm HPE-HNSs.These results demonstrate that integral HPE-HNSs determine the in vivo performance of HPEHNSs.This study provides insight into the in vivo fate of intravenous amorphous nanosuspensions.

Investigating the crucial roles of aliphatic tails in disulfide bond-linked docetaxel prodrug nanoassemblies

Disulfide bond-bridging strategy has been extensively utilized to construct tumor specificity-responsive aliphatic prodrug nanoparticles(PNPs) for precise cancer therapy. Yet, there is no research shedding light on the impacts of the saturation and cis-trans configuration of aliphatic tails on the self-assembly capacity of disulfide bond-linked prodrugs and the in vivo delivery fate of PNPs. Herein, five disulfide bond-linked docetaxelfatty acid prodrugs are designed and synthesized by using stearic acid, elaidic acid, oleic acid, linoleic acid and linolenic acid as the aliphatic tails, respectively. Interestingly, the cistrans configuration of aliphatic tails significantly influences the self-assembly features of prodrugs, and elaidic acid-linked prodrug with a trans double bond show poor self-assembly capacity. Although the aliphatic tails have almost no effect on the redox-sensitive drug release and cytotoxicity, different aliphatic tails significantly influence the chemical stability of prodrugs and the colloidal stability of PNPs, thus affecting the in vivo pharmacokinetics, biodistribution and antitumor efficacy of PNPs. Our findings illustrate how aliphatic tails affect the assembly characteristic of disulfide bond-linked aliphatic prodrugs and the in vivo delivery fate of PNPs, and thus provide theoretical basis for future development of disulfide bond-bridged aliphatic prodrugs.

The intragastrointestinal fate of paclitaxel-loaded micelles:Implications on oral drug delivery

The goal of the present study is to elucidate the intragastrointestinal fate of micellar delivery systems by monitoring fluorescently labeled different micelles and the model drug paclitaxel(PTX).Both in vitro and ex vivo leakage studies showed fast PTX release in fluids while micelles remained intact,except in fedstate simulated intestinal fluid and fasted-state pig intestinal fluid,thus referring to the intact absorption of micelles and PTX leakage in the gastrointestinal tract with D-a-tocopherol polyethylene glycol 1000 succinate(TPGS)micelles showing higher stability than other micelles.All groups of micelles were absorbed intact in Caco-2 and Caco-2/HT29-MTX cell models and the absorption of TPGS micelles was found to be higher than other micelles.The transport of the micelles across Caco-2/Raji(1.6%-3.5%),Caco-2(0.8%-1%),and Caco-2/HT29-MTX(0.58%-1%)cell monolayers further verified the absorption of micelles and their subsequent transport;however,more TPGS micelles transported across cell monolayers than other groups.Moreover,the histological examination also confirmed that micelles ente red the enterocytes and were transported to basolateral tissues and TPGS showed the stronger ability of penetration than other groups.Thus,these results are succinctly presenting the absorption of intact micelles in GIT confirmed by imaging evidence with prior leakage of the drug,upta ke by enterocytes and the transport of micelles that survive the digestion by enterocytes and mainly by microfold cells in material nature dependent way with TPGS showing better results than other groups.In conclusion,these results identify the mechanism by which the gastrointestinal tract processes micelles and point to the likely use of this approach in the design of micelles-based therapies.

Current research trends of nanomedicines

Owing to the inherent shortcomings of traditional therapeutic drugs in terms of inadequate therapeutic efficacy and toxicity in clinical treatment,nanomedicine designs have received widespread attention with significantly improved efficacy and reduced non-target side effects.Nanomedicines hold tremendous theranostic potential for treating,monitoring,diagnosing,and controlling various diseases and are attracting an unfathomable amount of input of research resources.Against the backdrop of an exponentially growing number of publications,it is imperative to help the audience get a panorama image of the research activities in the field of nanomedicines.Herein,this review elaborates on the development trends of nanomedicines,emerging nanocarriers,in vivo fate and safety of nanomedicines,and their extensive applications.Moreover,the potential challenges and the obstacles hindering the clinical translation of nanomedicines are also discussed.The elaboration on various aspects of the research trends of nanomedicines may help enlighten the readers and set the route for future endeavors.

Gastrointestinal lipolysis and trans-epithelial transport of SMEDDS via oral route

Self-microemulsifying drug delivery systems(SMEDDSs)have recently returned to the limelight of academia and industry due to their enormous potential in oral delivery of biomacromolecules.However,information on gastrointestinal lipolysis and trans-epithelial transport of SMEDDS is rare.Aggregation-caused quenching(ACQ)fuorescent probes are utilized to visualize the in vivo behaviors of SMEDDSs,because the released probes during lipolysis are quenched upon contacting water.Two SMEDDSs composed of medium chain triglyceride and different ratios of Tween-80 and PEG-400 are set as models,meanwhile Neoral?was used as a control.The SMEDDS droplets reside in the digestive tract for as long as 24 h and obey frst order kinetic law of lipolysis.The increased chain length of the triglyceride decreases the lipolysis of the SMEDDSs.Ex vivo imaging of main tissues and histological examination confrm the trans-epithelial transportation of the SMEDDS droplets.Approximately 2%-4%of the given SMEDDSs are transported via the lymph route following epithelial uptake,while liver is the main termination.Caco-2 cell lines confrm the cellular uptake and trans-epithelial transport.In conclusion,a fraction of SMEDDSs can survive the lipolysis in the gastrointestinal tract,permeate across the epithelia,translocate via the lymph,and accumulate mainly in the liver.

Whole-body PET tracking of a D-dodecapeptide and its radiotheranostic potential for PD-L1 overexpressing tumors

Peptides that are composed of dextrorotary(D)-amino acids have gained increasing attention as a potential therapeutic class.However,our understanding of the in vivo fate of D-peptides is limited.This highlights the need for whole-body,quantitative tracking of D-peptides to better understand how they interact with the living body.Here,we used mouse models to track the movement of a programmed death-ligand 1(PD-L1)-targeting D-dodecapeptide antagonist(DPA)using positron emission tomography(PET).More specifically,we profiled the metabolic routes of[^(64)Cu]DPA and investigated the tumor engagement of[^(64)Cu/^(68)Ga]DPA in mouse models.Our results revealed that intact[^(64)Cu/^(68)Ga]DPA was primarily eliminated by the kidneys and had a notable accumulation in tumors.Moreover,a single dose of[^(64)Cu]DPA effectively delayed tumor growth and improved the survival of mice.Collectively,these results not only deepen our knowledge of the in vivo fate of D-peptides,but also underscore the utility of D-peptides as radiopharmaceuticals.

The long-circulating effect of pegylated nanoparticles revisited via simultaneous monitoring of both the drug payloads and nanocarriers

The long-circulating effect is revisited by simultaneous monitoring of the drug payloads and nanocarriers following intravenous administration of doxorubicin(DOX)-loaded methoxy polyethylene glycol-polycaprolactone(mPEG-PCL) nanoparticles. Comparison of the kinetic profiles of both DOX and nanocarriers verifies the long-circulating effect, though of limited degree, as a result of pegylation. The nanocarrier profiles display fast clearance from the blood despite dense PEG decoration;DOX is cleared faster than the nanocarriers. The nanocarriers circulate longer than DOX in the blood, suggesting possible leakage of DOX from the nanocarriers. Hepatic accumulation is the highest among all organs and tissues investigated, which however is reversely proportionate to blood circulation time. Pegylation and reduction in particle size prove to extend circulation of drug nanocarriers in the blood with simultaneous decrease in uptake by various organs of the mononuclear phagocytic system. It is concluded that the long-circulating effect of mPEG-PCL nanoparticles is reconfirmed by monitoring of either DOX or the nanocarriers, but the faster clearance of DOX suggests possible leakage of a fraction of the payloads. The findings of this study are of potential translational significance in design of nanocarriers towards optimization of both therapeutic and toxic effects.

The feasibility of oral targeted drug delivery: Gut immune to particulates?

Targeted drug delivery is constantly updated with a better understanding of the physiological and pathological features of various diseases. Depending on high safety, good compliance and many other undeniable advantages, attempts have been undertaken to complete an intravenous-to-oral conversion of targeted drug delivery. However, oral delivery of particulates to systemic circulation is highly challenging due to the biochemical aggressivity and immune exclusion in the gut that restrain absorption and access to the bloodstream. Little is known about the feasibility of targeted drug delivery via oral administration(oral targeting) to a remote site beyond the gastrointestinal tract. To this end, this review proactively contributes to a special dissection on the feasibility of oral targeting. We discussed the theoretical basis of oral targeting, the biological barriers of absorption, the in vivo fate and transport mechanisms of drug vehicles, and the effect of structural evolution of vehicles on oral targeting as well. At last, a feasibility analysis on oral targeting was performed based on the integration of currently available information. The innate defense of intestinal epithelium does not allow influx of more particulates into the peripheral blood through enterocytes. Therefore, limited evidence and lacking exact quantification of systemically exposed particles fail to support much success with oral targeting. Nevertheless, the lymphatic pathway may serve as a potentially alternative portal of peroral particles into the remote target sites via M-cell uptake.

Ionic co-aggregates(ICAs)based oral drug delivery:Solubilization and permeability improvement

Due to the overwhelming percentage of poorly water-soluble drugs,pharmaceutical industry is in urgent need of efficient approaches for solubilization and permeability improvement.Salts consisting of lipophilic fatty acid anions and hydrophilic choline cations are found to be surface active and able to form ionic co-aggregates(ICAs)in water.Choline oleate-based ICAs significantly enhance oral absorption of paclitaxel(PTX)as compared with cremophor EL-based micelles(MCs).Aggregation-caused quenching probes enable tracking of intact ICAs in in vivo transport and cellular interaction.Prolonged intestinal retention of ICAs than MCs implies stronger solubilizing capability in vivo.Ex vivo imaging of major organs and intestinal tracts suggests transepithelial transport of intact ICAs.Cellular studies support the enhanced absorption of PTX and transmembrane transport of intact ICAs.In conclusion,ICAs,consisting of lipophilic ions and hydrophilic counter-ions,are of great potential in delivery of poorly water-soluble drugs by enhancing solubility and permeability.