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Brain-targeted drug delivery poses a great challenge due to the blood-brain barrier (BBB). In a previous study, we have developed a peptide-modified stealth liposome (SP-sLip) to enhance BBB penetration via the adsorption of apolipoproteins in plasma. SP is an 11-amino acid peptide derived from 25 to 35 of the Amyloid β peptide (Aβ 1-42 ), which is a nature ligand of apolipoproteins. Although freshly prepared SP-sLip exhibited efficient brain targeting performance, it occured self-aggregation and instability in storage. In this study, we developed a D-peptide ligand according to the reverse sequence of SP with D-amino acids, known as D SP, to improve the stability in storage. Notably, D SP exhibited a reduced tendency for self-aggregation and improved stability in comparison to the SP peptide. Furthermore, compared to SP-sLip, D SP-modified sLip ( D SP-sLip) demonstrated enhanced stability (>2 weeks), prolonged blood circulation (AUC increased 44.4%), reduced liver and spleen accumulation (reduced by 2.23 times and 1.86 times) with comparable brain-targeting efficiency. Similar to SP-sLip, D SP-sLip selectively adsorbed apolipoprotein A1, E, and J in the blood to form functionalized protein corona, thus crossing BBB via apolipoprotein receptor-mediated transcytosis. These findings underscored the importance of ligand stability in the in vitro and in vivo performance of brain-targeted liposomes, therefore paving the way for the design and optimization of efficient and stable nanocarriers., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Nanomedicines are of increasing scrutiny due to their improved efficacy and/or mitigated side effects. They can be integrated with many other therapeutics to further boost the clinical benefits. Among those, herbal medicines are arousing great interest to be combined with nanomedicines to exert synergistic effects in multifaceted mechanisms. The in vivo performance of nanomedicines which determines the therapeutic efficacy and safety is believed to be heavily influenced by the physio-pathological characters of the body. Activation of multiple immune factors, e.g., complement system, phagocytic cells, lymphocytes, and among many others, can affect the fate of nanomedicines in blood circulation, biodistribution, interaction with single cells and intracellular transport. Immunomodulatory effects and metabolic regulation by herbal medicines have been widely witnessed during the past decades, which alter the physio-pathological conditions and dramatically affect in vivo delivery of nanomedicines. In this review, we summarize recent progress of understanding on the in vivo delivery process of nanomedicines and analyze the major affecting factors that regulate the interaction of nanomedicines with organisms. We discuss the immunomodulatory roles and metabolic regulation by herbal medicines and their effects on in vivo delivery process of nanomedicines, as well as the prospective clinical benefits from the combination of nanomedicines and herbal medicines., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

With significantly decreased light scattering and tissue autofluorescence, fluorescence imaging in the second near infrared (NIR-II, 1000-1700 nm) region has been heavily explored in biomedical field recently. Silver sulfide quantum dots (Ag 2 S QDs) with unique optical properties were one of the most classic NIR-II imaging probes. However, the Ag 2 S QDs for in vivo purpose were mainly obtain by oil phase-based high-temperature route at present. Here, we proposed a mild aqueous route to prepare NIR-II emissive Ag 2 S QDs for in vivo tumor imaging. Original Ag 2 S QDs was obtained by mixing sodium sulfide and silver nitrate in a thiol-terminated polyethylene glycol (mPEG-SH) solution. Treating the original Ag 2 S QDs with extra mPEG-SH ligands produced highly PEGyalted Ag 2 S QDs. These re-PEGylated Ag 2 S QDs exhibited much better blood circulation and tumor accumulation in vivo comparing with the original ones, which can serve as excellent tumor imaging probes. The whole-body blood vessel imaging of living mice was achieved with high resolution, the bio-distribution of these QDs were studied by NIR-II imaging as well. This work also highlighted the importance of ligand density for tumor targeting., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Nanosized lipodisks with flat circular phospholipid bilayers surrounded by PEGylated edges have demonstrated promise in drug delivery. In the present work, a lipodisk-based paclitaxel and melittin co-delivery system functionalized with glycopeptide 9G-A7R (9G-A7R-Disk/PTX/melittin) was successfully constructed, in which melittin which was fully protected from proteolysis and hemolysis was effectively reduced. The ratio of paclitaxel to melittin in lipodisks could be accurately controlled through a film hydration-adsorption method. Paclitaxel combined with melittin showed synergism against U87 cells in vitro, and 9G-A7R-Disk/PTX/melittin demonstrated an enhanced anti-glioma effect in vivo, significantly prolonging the survival time of glioma-bearing mice. The results suggested a promising formulation for the co-delivery of paclitaxel/melittin and glioma-targeted therapy.

The safe and efficient delivery of chemotherapeutic agents remains critical to anticancer therapy. Herein, we report on a targeted drug delivery system based upon a modified cell membrane coating technique and drug nanocrystals (NCs). Specifically, red blood cell (RBC) membrane was modified with targeting peptides through a facile insertion method involving avidin-biotin interactions. The RBC membrane-coated drug NCs (RBC-NCs) exhibited high drug loading, long-term stability, excellent biocompatibility, and prolonged retention time, all of which make them suitable for effective drug delivery. When modified with the tumor-targeting peptide c(RGDyK), the resulting RGD-RBC-NCs showed superior tumor accumulation and therapeutic efficacy both in mice bearing a subcutaneous tumor as well as orthotropic glioma. RBC-NC therapeutics can be readily generalized to the delivery of various drugs and for the treatment of a wide range of cancers.

Targeted drug delivery is emerging as a promising strategy to achieve better clinical outcomes. Actively targeted drug delivery that utilizes overexpressed receptors or antigens on diseased tissues is receiving increasing scrutiny, especially due to the uncertainty of existence of the enhanced permeability and retention (EPR) effect in cancer patients. Peptide ligands are advantageous over other classes of targeting ligands due to their accessibility of high-throughput screening, ease of synthesis, high specificity and affinity, etc. In this review, we briefly summarize the resources of peptide ligands and discuss the pitfalls and perspectives of peptide ligand-mediated targeted delivery of nanomedicines.

Targeting ligands are anticipated to facilitate the precise delivery of therapeutic agents to diseased tissues; however, they may also severely affect the interaction of nanocarriers with plasma proteins. Here, we study the immunocompatibility of brain-targeted liposomes, which inversely correlates with absorbed natural IgM. Modification of long, stable positively charged peptide ligands on liposomes is inclined to absorb natural IgM, leading to rapid clearance and enhanced immunogenicity. Small peptidomimetic D8 developed by computer-aided peptide design exhibits improved immunocompatibility by attenuating natural IgM absorption. The present study highlights the effects of peptide ligands on the formed protein corona and in vivo fate of liposomes. Stable positively charged peptide ligands play double-edged roles in targeted delivery, preserving in vivo bioactivities for binding receptors and long-term unfavorable interactions with the innate immune system. The development of D8 provides insights into how to rationally design immunocompatible drug delivery systems by modulating the protein corona composition.

The receptor associated protein (RAP) is a 39 kDa chaperone protein, binding tightly to low-density lipoprotein receptor-related protein-1 (LRP1) that is overexpressed in glioma, tumor neovasculature, vasculogenic mimicry (VM), the blood-brain barrier (BBB) and the blood-brain tumor barrier (BBTB). Herein, we miniaturized the RAP protein into a short peptide RAP12 (EAKIEKHNHYQK) aiding by computer-aided peptide design technique. RAP12 contained the essential lysines at the positions 253 and 256. The binding affinity of RAP12 to LRP1 was theoretically and experimentally evaluated. In cellular level, RAP12 could effectively internalize into U87, HUVEC and bEnd.3 cells. When modified on the surface of PEG-PLA micelles (RAP12-PEG-PLA), RAP12 could effectively facilitate the penetration of micelles through the BBB/BBTB in vitro/vivo. Paclitaxel-loaded RAP12-PEG-PLA could remarkably inhibit the growth of glioma cells and the formation of tumor neovasculature and VM, significantly prolong the median survival time of nude mice bearing intracranial glioma in comparison to model mice treated with plain micelles or Taxol. These results suggested that the RAP12 held the potential for multifunctional glioma-targeted drug delivery., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The current prognosis of glioma patients remains poor after intensive multimodal treatments, which is partially due to the existence of the blood-brain tumor barrier (BBTB). In the present study, a novel "bifunctional ligand" (termed D VS) was developed by retro-inverso isomerization. D VS is a ligand of integrins highly expressed on glioma cells and tumor neovasculature. D VS exhibited exceptional stability in serum and demonstrated significantly higher targeting efficiency for glioma and HUVEC cells compared with the parent L-peptide. As a result, D VS modified micelles ( D VS-MS) exhibited high encapsulation efficiency of doxorubicin, ideal size distribution, and sustained release behavior of the payload. In vivo studies showed that D VS-MS could target and efficiently deliver fluorescence to tumor cells and tumor vasculature not only in the mice bearing subcutaneous tumors but also in those bearing intracranial tumors. Moreover, doxorubicin loaded D VS modified micelles exerted potent tumor growth inhibitory activity against subcutaneous and intracranial human glioma in comparison to drug loaded plain micelles and L VS modified micelles. Therefore, D VS appears to be a suitable targeting ligand with potential applications for glioma targeted drug delivery.

Glioma is among the most formidable brain cancers due to location in the brain. Cholera toxin subunit B (CTB) is investigated to facilitate multifunctional glioma-targeted drug delivery by targeting the glycosphingolipid GM1 expressed in the blood-brain barrier (BBB), neovasulature, and glioma cells. When modified on the surface of poly(lactic-co-glycolic acid) (PLGA) nanoparticles (CTB-NPs), CTB fully retains its bioactivity after 24 h incubation in the fresh mouse plasma. The formed protein corona (PC) of CTB-NP and plain PLGA nanoparticles (NP) after incubation in plasma is analyzed using liquid chromatography tandem massspectrometry (nano-LC-MS/MS). CTB modification does not alter the protein components of the formed PC, macrophage phagocytosis, or pharmacokinetic profiles. CTB-NP can efficiently penetrate the in vitro BBB model and target glioma cells and human umbilical vascular endothelial cells. Paclitaxel is loaded in NP (NP/PTX) and CTB-NP (CTB-NP/PTX), and their antiglioma effects are assessed in nude mice bearing intracranial glioma. CTB-NP/PTX can efficiently induce apoptosis of intracranial glioma cells and ablate neovasulature in vivo, resulting in significant prolongation of survival of nude mice bearing intracranial glioma (34 d) in comparison to those treated with NP/PTX (29 d), Taxol (24 d), and saline (21 d). The present study suggests a potential multifunctional glioma-targeted drug delivery system enabled by cholera toxin subunit B., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

On-demand pain relief systems would be very helpful additions to the armamentarium of pain management. Near-infrared triggered drug delivery systems have demonstrated the potential to provide such care. However, challenges remain in making such systems as stimulus-sensitive as possible, to enhance depth of tissue penetration, repeatability of triggering, and safety. Here we developed liposomes containing the local anesthetic tetrodotoxin and also containing a photosensitizer and gold nanorods that were excitable at the same near-infrared wavelength. The combination of triggering mechanisms enhanced the photosensitivity and repeatability of the system in vitro when compared with liposomes with a single photoresponsive component. In vivo, on-demand local anesthesia could be induced with a low irradiance and short irradiation duration, and liposomes containing both photosensitizer and gold nanorods were more effective than those containing just one photoresponsive component. Tissue reaction was benign.

The blood brain barrier separates the circulating blood from the extracellular fluid in the central nervous system and thus presents an essential obstacle to brain transport of therapeutics. Herein, we report on an effective brain-targeted drug delivery system that combines a robust red blood cell membrane-coated nanoparticle (RBCNP) with a unique neurotoxin-derived targeting moiety. The RBCNPs retain the complex biological functions of natural cell membranes while exhibiting physicochemical properties that are suitable for effective drug delivery. CDX peptide is derived from candoxin and shows high binding affinity with nicotinic acetylcholine receptors (nAChRs) expressed on the surface of brain endothelial cells. Through a facile yet robust approach, we successfully incorporate D CDX peptides onto the surface of RBCNPs without compromising the peptide's brain targeting ability. The resulting D CDX-RBCNPs show promising brain targeting efficiency both in vitro and in vivo. Using a glioma mouse model, we demonstrate that doxorubicin-loaded D CDX-RBCNPs have superior therapeutic efficacy and markedly reduced toxicity as compared to the nontargeted drug formulations. While RBCNPs are used as a model system to evaluate the surface modification approach, the reported method can be readily generalized to various types of cell membrane-derived nanocarriers for broad medical applications., (Copyright © 2017 Elsevier B.V. All rights reserved.)

GRP78, a specific cancer cell-surface marker, is implicated in cancer cells proliferation, apoptosis resistance, metastasis and drug resistance. l-VAP (SNTRVAP) is a tumor homing peptide exhibiting high binding affinity in vitro to GRP78 protein overexpressed on glioma, glioma stem cells, vasculogenic mimicry and neovasculature. Even though short peptides are often non-immunogenic and demonstrate high affinity to tumor cells, their targeting efficacy is always undermined by rapid blood clearance and enzymatic degradation. In the present study, two d peptides RI-VAP (retro inverso isomer of l-VAP) and d-VAP (retro isomer of l-VAP) were developed by structure-guided peptide design and retro-inverso isomerization technique for glioma targeting. RI-VAP and d-VAP were predicted to bind their receptor GRP78 protein with similar binding affinity, which was experimentally confirmed. The results of in vivo imaging demonstrated that RI-VAP and d-VAP had remarkably advantage over l-VAP for tumor accumulation. In addition, RI-VAP and d-VAP modified paclitaxel-loaded polymeric micelle had better anti-tumor efficacy in comparison to taxol, paclitaxel-loaded plain micelles and l-VAP modified micelles. Overall, the VAP modified micelles suggested in the present study could effectively achieve glioma-targeted drug delivery, validating the potential of the stable VAP peptides in improving the therapeutic efficacy of paclitaxel for glioma., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The rapid proliferation of glioma relies on vigorous angiogenesis for the supply of essential nutrients; thus, a radical method of antiglioma therapy should include blocking tumor neovasculature formation. A phage display selected heptapeptide, the glioma-initiating cell peptide GICP, was previously reported as a ligand of VAV3 protein (a Rho GTPase guanine nucleotide exchange factor), which is overexpressed on glioma cells and tumor neovasculature. Therefore, GICP holds potential for the multifunctional targeting of glioma (tumor cells and neovasculature). We developed GICP-modified micelle-based paclitaxel delivery systems for antiglioma therapy in vitro and in vivo. GICP and GICP-modified PEG-PLA micelles (GICP-PEG-PLA) could be significantly taken up by U87MG cells, a human cell line derived from malignant gliomas and human umbilical vein endothelial cells (HUVECs). Furthermore, GICP-PEG-PLA micelles demonstrated enhanced penetration in a tumor spheroid model in vitro in comparison to unmodified micelles. In vivo, DiR-loaded GICP-PEG-PLA micelles exhibited superior accumulation in the tumor region by targeting neovasculature and glioma cells in nude mice bearing subcutaneous glioma. When loaded with paclitaxel, GICP-PEG-PLA micelles could more effectively suppress tumor growth and neovasculature formation than unmodified micelles in vivo. Our results indicated that GICP could serve as a promising multifunctional ligand for glioma targeting.

Light has many desirable properties as the stimulus for triggerable drug delivery systems. Inorganic nanomaterials are often key components in transducing light into drug delivery events. The nature of the light and the inorganic materials can affect the efficacy and safety of the drug delivery system.

Peptide ligands consisting of l-amino acids are subject to proteolysis in vivo. When modified on the surface of nanocarriers, those peptide ligands would readily degrade and the targeting efficacy is significantly attenuated. It has received increasing scrutiny to design stable peptide ligands for targeted drug delivery. Here, we present the design of a stable peptide ligand by the formation of a head-to-tail amide bond as an example. Even though the linear l-peptide A7R (termed L A7R) can bind specifically to vascular endothelial growth factor receptor 2 (VEGFR2) and neuropilin-1 (NRP-1) that are overexpressed on glioma cells, neovasculature and glioma vasculogenic mimicry (VM), the tumor-homing capacity of L A7R is greatly impaired in vivo due to proteolysis (e.g. in the serum). A cyclic A7R (cA7R) peptide was identified by computer-aided peptide design and synthesized with high yield by combining solid phase peptide synthesis and native chemical ligation. The binding of cA7R to both receptors was theoretically and experimentally assessed. In our simulated model hydrophobic and ionic interactions dominated the binding of L A7R to receptors. It is very interesting that cA7R adopting a different structure from L A7R retained high binding affinities to receptors without affecting the hydrophobic and ionic interactions. After head-to-tail cyclization by the formation of an amide bond, cA7R exhibited exceptional stability in mouse serum. Either cA7R or L A7R was conjugated on the surface of doxorubicin (DOX) loaded liposomes (cA7R-LS/DOX or L A7R-LS/DOX). The results of in vitro cellular assays indicated that cA7R-LS/DOX not only displayed stronger anti-proliferative effect against glioma cells, but also demonstrated to be more efficient in destruction of VM and HUVEC tubes in comparison to L A7R-LS/DOX and plain liposomes (LS/DOX, without peptide conjugation). cA7R conjugation could achieve significantly higher accumulation of liposomes in glioma than did L A7R conjugation, which in turn, cA7R-LS/DOX could substantially suppress subcutaneous tumor growth when compared with other DOX formulations (free DOX, LS/DOX and L A7R-LS/DOX). The designed cyclic A7R exhibited the capability of targeting glioma cells, neovasculature and VM simultaneously in vivo. Considering the ease of synthesis, high binding affinity to receptors and increased stability of cA7R peptide in the present study, the design of head-to-tail cyclized peptides by the formation of amide bond based on computer-aided peptide design presents an alternative method to identify proteolytically stable peptide ligands., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A large proportion of the payload delivered by nanoparticulate therapies is deposited not in the desired target destination but in off-target locations such as the liver and spleen. Here, we demonstrate that phototargeting can improve the specific targeting of nanoparticles to tumors. The combination of efficient triplet-triplet annihilation upconversion (TTA-UC) and Förster resonance energy transfer (FRET) processes allowed in vivo phototargeting at a safe irradiance (200 mW/cm(2)) over a short period (5 min) using green light.

Polyketals, which can be biodegradable, have good biocompatibility, and are pH-sensitive, could have broad applicability in drug delivery and other biomedical applications. However, facile synthesis of high molecular weight polyketals is challenging, and short durations of drug release from polyketal particulate formulations limit their application in drug delivery. Here we report the synthesis of a di-isopropenyl ether monomer and its use to synthesize high molecular weight estradiol-polyketal conjugates by addition polymerization. Microparticles were prepared from the estradiol-polyketal conjugate, where estradiol was incorporated into the polymer backbone. The particles had high drug loading and significantly prolonged drug release. Release of estradiol from the drug-polyketal conjugate microparticles was acid-responsive, as evidenced by faster drug release at low pH and with co-incorporation of PLGA. Tissue reaction to the microparticles was benign in vivo. Polyketal drug conjugates are promising candidates for long-acting drug delivery systems to treat chronic diseases.

Protein and peptide toxins offer an invaluable source for the development of actively targeted drug delivery systems. They avidly bind to a variety of cognate receptors, some of which are expressed or even up-regulated in diseased tissues and biological barriers. Protein and peptide toxins or their derivatives can act as ligands to facilitate tissue- or organ-specific accumulation of therapeutics. Some toxins have evolved from a relatively small number of structural frameworks that are particularly suitable for addressing the crucial issues of potency and stability, making them an instrumental source of leads and templates for targeted therapy. The focus of this review is on protein and peptide toxins for the development of targeted drug delivery systems and molecular therapies. We summarize disease- and biological barrier-related toxin receptors, as well as targeted drug delivery strategies inspired by those receptors. The design of new therapeutics based on protein and peptide toxins is also discussed., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Lysosomes of brain capillary endothelial cells are implicated in nicotine acetylcholine receptor (nAChR)-mediated transcytosis and act as an enzymatic barrier for the transport of peptide ligands to the brain. A D-peptide ligand of nAChRs (termed (D)CDX), which binds to nAChRs with an IC50 value of 84.5 nM, was developed by retro-inverso isomerization. (D)CDX displayed exceptional stability in lysosomal homogenate and serum, and demonstrated significantly higher transcytosis efficiency in an in vitro blood-brain barrier monolayer compared with the parent L-peptide. When modified on liposomal surface, (D)CDX facilitated significant brain-targeted delivery of liposomes. As a result, brain-targeted delivery of (D)CDX modified liposomes enhanced therapeutic efficiency of encapsulated doxorubicin for glioblastoma. This study illustrates the importance of ligand stability in nAChRs-mediated transcytosis, and paves the way for developing stable brain-targeted entities., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The blood-brain barrier (BBB) prevents most drugs from reaching the site of central nervous system (CNS) diseases, intensively confining the therapeutic efficiency. Angiopep-2 (here termed (L)Angiopep), which is a 19-mer peptide derived from human Kunitz domain, can trigger transcytosis and traverse the BBB by recognizing low density lipoprotein-related protein 1 (LRP-1) expressed on the brain capillary endothelial cells. Various enzymes in the blood and the BBB, however, present multiple metabolic barriers to peptide-inspired brain-targeted drug delivery. Here we designed a retro-inverso isomer of (L)Angiopep, termed (D)Angiopep, to inspire brain-targeted drug delivery. Both (D)Angiopep and (L)Angiopep displayed high uptake capacity in LRP-1 overexpressed cells, including bEnd.3 and U87 cells. (D)Angiopep demonstrated lower uptake efficiency in both cell lines than did (L)Angiopep, suggestive of lower binding affinity to LRP-1 of the d-peptide. (D)Angiopep was resistant to proteolysis in fresh rat blood serum, while more than 85% of (L)Angiopep disappeared within 2 h. Endocytosed (D)Angiopep and (L)Angiopep were found to be colocalized with lysosomal compartments of bEnd.3 cells, indicating that susceptibility to proteolysis of (L)Angiopep in the BBB may further attenuate its transcytosis efficiency. In vivo, (D)Angiopep modified PEG-DSPE micelles displayed high distribution in normal brain and intracranial glioblastoma. Due to the expression of LRP-1 on the BBB and glioblastoma cells, proteolytically stable (D)Angiopep holds much potential for designing two-order brain tumor targeted delivery systems.

Treatment of malignant gliomas remains a challenge irrespective of the recent improvements. Chemotherapeutic agents for malignant gliomas have been particularly inefficient for the existence of blood-tumor barrier (BTB), which hampers the accumulation and uptake in tumor. Moreover, even though blood-brain barrier (BBB) is compromised to some extent under the situation of malignant gliomas, it remains to be the obstacle influencing the therapeutic efficacies via systemic administration. Fortunately, there are many receptors over-expressed on the BTB (glioma cells and/or tumor microvessels) that can mediate ligand modified drug delivery systems targeting to gliomas and enhance tumor uptake. On the other hand, numerous routes have also been explored to circumvent the BBB. In this manuscript, we elucidate the BBB/BTB status under the situation of malignant gliomas and review the receptors over-expressed on BTB and the malignant gliomas targeted drug delivery strategies. We also discuss the perspective of malignant gliomas targeted drug delivery systems with new concepts.

10-Hydroxycamptothecin (HCPT) loaded PLA microbubbles, used as an ultrasound-triggered drug delivery system, were fabricated by a double emulsion-solvent evaporation method. The obtained microbubbles were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and confocal laser scanning microscope (CLSM). In addition, the effect of diagnostic ultrasound exposure on BEL-7402 cells combined with HCPT-loaded PLA microbubbles was evaluated using cytotoxicity assay, CLSM and flow cytometry (FCM). It was found that the HCPT-loaded PLA microbubbles showed smooth surface and spherical shape, and the drug was amorphously dispersed within the shell and the drug loading content reached up to 1.69%. Nearly 20% of HCPT was released upon exposure to diagnostic ultrasound at frequency of 3.5MHz for 10min. Moreover, HCPT fluorescence in the cells treated only with the HCPT-loaded PLA microbubbles was discernible, but less intense, while those treated with the microbubbles in conjunction with ultrasound exposure was evident and intense, indicating an increased cellular uptake of HCPT by ultrasound exposure. Cytotoxicity test on BEL-7402 cells indicated that the HCPT-loaded PLA microbubbles combined with ultrasound exposure were more cytotoxic than the microbubbles alone. The results suggest that the combination of drug loaded PLA microbubbles and diagnostic ultrasound exposure exhibit an effective intracellular drug uptake by tumor cells, indicating their great potential for antitumor therapy., (Copyright © 2011. Published by Elsevier B.V.)

Three-finger snake neurotoxins have been widely investigated for their high binding affinities with nicotinic acetylcholine receptors (nAChRs), which are widely expressed in the central nervous system including the blood-brain barrier and thus mediate intracranial drug delivery. The loop 2 segments of three-finger snake neurotoxins are considered as the binding domain with nAChRs, and thus, they may have the potential to enhance drug or drug delivery system intracranial transport. In the present work, binding of the synthetic peptides to the neuronal nAChRs was assessed by measuring their ability to inhibit the binding of (125)I-α-bungarotoxin to the receptor. The loop 2 segment of Ophiophagus hannah toxin b (KC2S) showed high binding affinity, and the competitive binding IC(50) value was 32.51 nM. Furthermore, the brain targeting efficiency of KC2S had been investigated in vitro and in vivo. The specific uptake by brain capillary endothelial cells (BCECs) demonstrated that KC2S could be endocytosized after binding with nAChRs. In vivo, the qualitative and quantitative biodistribution results of fluorescent dyes (DiR or coumarin-6) indicated that KC2S modified poly(ethylene glycol)-poly(lactic acid) micelles (KC2S-PEG-PLA micelles) could enhance intracranial drug delivery. Furthermore, intravenous treatment with paclitaxel-encapsulated KC2S-PEG-PLA micelles (KC2S-PEG-PLA-PTX micelles) afforded robust inhibition of intracranial glioblastoma. The median survival time of KC2S-PEG-PLA-PTX-micelle-treated mice (47.5 days) was significantly longer than that of mice treated by mPEG-PLA-PTX micelles (41.5 days), Taxol (38.5 days), or saline (34 days). Compared with the short peptide derived from rabies virus glycoprotein (RVG29) that has been previously reported as an excellent brain targeting ligand, KC2S has a similar binding affinity with neuronal nAChRs but fewer amino acid residues. Thus, we concluded that the loop 2 segment of Ophiophagus hannah toxin b could bind with neuronal nAChRs and thus enhance intracranial drug delivery for the treatment of central nervous system diseases.

In this study, folate-conjugated polymer micelles were synthesized by mixing folate-poly(ethylene glycol)-distearoylphosphatidylethanolamine (FA-PEG-DSPE) and methoxy-poly(ethylene glycol)-distearoylphosphatidylethanolamine (MPEG-DSPE) to encapsulate anticancer agent 9-nitro-camptothecin (9-NC). Formulations were characterized by critical micellization concentration (CMC) values of copolymers, micelle particle size, zeta-potential, encapsulation efficiency and drug loading efficiency. The molar ratio of FA-PEG-DSPE and MPEG-DSPE was chosen to avoid the macrophages and at the same time express highly active targeting ability. The targeting ability of folate-conjugated polymer micelles was investigated against three kinds of tumor cell lines (HeLa, SGC7901 and BXPC3). The drug efficacy in vitro of folate-conjugated polymer micelles was evaluated by using the methylthiazoletetrazolium (MTT) method. The results showed that the CMC values of MPEG-DSPE and FA-PEG-DSPE were 0.97 x 10(-5)M and 1.0 x 10(-5)M, respectively. The average size of folate-conjugated micelle was about 21-24 nm and the micelle size distribution of both empty and drug-loaded micelles were rather narrow. The encapsulation efficiency and drug loading efficiency were 97.6% and 4.64%, respectively. The drug-loaded micelles were stable during storage at 4 degrees C for 4 weeks. Micelles maintain the similar size and did not show 9-NC leakage. The best molar ratio of FA-PEG-DSPE and MPEG-DSPE in folate-conjugated micelles was 1:100 which can effectively solubilize 9-NC, avoid the macrophages in vitro and has a higher anti-tumor activity than both drug-loaded MPEG-DSPE micelles and free anticancer agents. The folate-conjugated polymer micelle which can avoid the macrophages is a kind of promising carrier for poorly soluble anticancer agents via folate receptor (FR) that mediated endocytosis to target tumor cells.

Alginate-chitosan (ALG-CS) blend gel beads were prepared based on Ca2+ or dual crosslinking with various proportions of alginate and chitosan. The homogeneous solution of alginate and chitosan was dripped into the solution of calcium chloride; the resultant Ca2+ single crosslinked beads were dipped in the solution of sodium sulfate sequentially to prepare dual crosslinked beads. The dual crosslinkage effectively promoted the stability of beads under gastrointestinal tract conditions. The sustained release profiles of single and dual crosslinked gel beads loaded bovine serum albumin (BSA), a model protein drug, were investigated in simulated gastric fluid (SGF), simulated intestinal fluid (SIF) and simulated colonic fluid (SCF). In SGF, compared to Ca2+ single crosslinked beads, from which BSA released fast and the cumulative drug release percentages were about 80% of all formations in 4 h, the BSA total release from dual crosslinked gel beads was no more than 3% in 8 h. In SIF and SCF, Ca2+ single crosslinked beads were disrupted soon associating with the fast drug release. As to the dual crosslinked beads, the BSA total release from the ALG-CS mass ratio 9:1 (81.24%) was higher than that of 7:3 and 5:5 (less than 60%) in 8 h in SIF; the BSA release from all beads was much faster in SCF than in SIF. The dual crosslinked beads incubated in gastrointestinal tract conditions, the BSA cumulative release of ALG-CS mass ratios 9:1, 7:3 and 5:5 were respectively 2.35, 1.96, 1.76% (in SGF 4 h), 82.86, 78.83, 52.91% (in SIF 3 h) and 97.84, 96.81, 87.26% (in SCF 3 h), which suggested that the dual crosslinked beads have potential small intestine or colon site-specific drug delivery property.