超临界CO2抗溶剂法制备紫杉醇缓释微球

采用超临界流体强制分散溶液技术,以D,L-聚乳酸和D,L-聚乳酸-聚乙二醇共聚物为载体材料,分别制备了紫杉醇缓释微球.通过扫描电镜、激光粒度仪检测微球外形及粒径分布;紫外吸光度法测量其载药量和包封率,恒温振荡透析法检测药物的体外释放性能;MTT法检测载药微球对Hela细胞的抑制作用.实验表明,两种载体的缓释微球球形度均较好,表面光滑,平均粒径较小,且粒径分布较窄.以聚乳酸和共聚物为载体的缓释微球载药量分别为5.4%±0.3%和5.3%±0.4%,包封率分别为51%±3%和45%±3%;药物释放呈缓释模式,共聚物载药微球药物释放速率较快.MTT法检测结果表明,载药微球对Hela细胞的增殖有明显抑制,共聚物载药微球对细胞增殖抑制更为明显.     

Use of top-down and bottom-up Fourier transform ion cyclotron resonance mass spectrometry for mapping calmodulin sites modified by platinum anticancer drugs

Calmodulin (CaM) is a highly conserved, ubiquitous, calcium-binding protein; it binds to and regulates many different protein targets, thereby functioning as a calcium sensor and signal transducer. CaM contains 9 methionine (Met), 1 histidine (His), 17 aspartic acid (Asp), and 23 glutamine acid (Glu) residues, all of which can potentially react with platinum compounds; thus, one-third of the CaM sequence is a possible binding target of platinum anticancer drugs, which represents a major challenge for identification of specific platinum modification sites. Here, top-down electron capture dissociation (ECD) was used to elucidate the transition metal-platinum(II) modification sites. By using a combination of top-down and bottom-up mass spectrometric (MS) approaches, 10 specific binding sites for mononuclear complexes, cisplatin and [Pt(dien)Cl]Cl, and dinuclear complex [{cis-PtCl(2)(NH(3))}(2)(μ-NH(2)(CH(2))(4)NH(2))] on CaM were identified. High resolution MS of cisplatin-modified CaM revealed that cisplatin mainly targets Met residues in solution at low molar ratios of cisplatin-CaM (2:1), by cross-linking Met residues. At a high molar ratio of cisplatin:CaM (8:1), up to 10 platinum(II) bind to Met, Asp, and Glu residues. [{cis-PtCl(2)(NH(3))}(2)(μ-NH(2)(CH(2))(4)NH(2))] forms mononuclear adducts with CaM. The alkanediamine linker between the two platinum centers dissociates due to a trans-labilization effect. [Pt(dien)Cl]Cl forms {Pt(dien)}(2+) adducts with CaM, and the preferential binding sites were identified as Met51, Met71, Met72, His107, Met109, Met124, Met144, Met145, Glu45 or Glu47, and Asp122 or Glu123. The binding of these complexes to CaM, particularly when binding involves loss of all four original ligands, is largely irreversible which could result in their failure to reach the target DNA or be responsible for unwanted side-effects during chemotherapy. Additionally, the cross-linking of cisplatin to CaM might lead to the loss of the biological function of CaM or CaM-Ca(2+) due to limiting the flexibility of the CaM or CaM-Ca(2+) complex to recognize target proteins or blocking the binding region of target proteins to CaM.     

Interfacial properties and in vitro cytotoxic effects of surface-modified near infrared absorbing Au-Au2S nanoparticles

Near infrared (NIR) absorbing Au-Au₂S nanoparticles were modified with surfactants of different hydrocarbon chain lengths to allow loading of anticancer drug, cisplatin. The interfacial interactions and surfactant chain length effects on drug loading, optical properties and cytotoxicity were discussed in this work. Short-chain surfactants were oriented closer to the surface normal and were adsorbed at higher densities. Surface modification also changed the optical properties of the particles. Notably, particles modified with short-chain surfactants exhibited a red shift, whereas particles modified with long-chain surfactants showed a blue shift. The in vitro cytotoxicity of drug-loaded surface-modified particles was dependent on the surfactants’ chain length. Significant cytotoxicity was observed for 1 mg/ml of drug-loaded particles using surfactants with the shortest chain length. After NIR triggered drug release, the released Pt compounds were observed to be cytotoxic, while remaining nanoparticles did not exhibit any cytotoxicity. Also, the released Pt compounds upon NIR irradiation of drug-loaded particles were observed to be more toxic and had a different molecular structure from cisplatin.     

Optimization of carboxylate-terminated poly(amidoamine) dendrimer-mediated cisplatin formulation

Cisplatin is mainly used in the treatment of ovarian, head and neck and testicular cancer. Poor solubility and non-specific interactions causes hurdles in the development of successful cisplatin formulation. There were few reports on poly(amidoamine) (PAMAM) dendrimer–cisplatin complexes for anticancer treatment. But the earlier research was mainly focused on therapeutic effect of PAMAM dendrimer–cisplatin complex, with less attention paid on the formulation development of these complexes. Objective of the present study is to optimize and validate the carboxylate-terminated, EDA core PAMAM dendrimer-based cisplatin formulation with respect to various variables such as dendrimer core, generation, drug entrapment, purification, yield, reproducibility, stability, storage and in-vitro release. Dendrimer–cisplatin complex was prepared by an efficient method which significantly increases the % platinum (Pt) content along with the product yield. Dendrimers showed reproducible (～27%) platinum loading by weight. Variation in core and generations does not produce significant change in the % Pt content. Percentage Pt content of dendrimeric formulation increases with increase in drug/dendrimer mole ratio. Formulation with low drug/dendrimer mole ratio showed delayed release compared to the higher drug/dendrimer mole ratio; these dendrimer formulations are stable in room temperature. In vitro release profiles of the stored dendrimer–cisplatin samples showed comparatively slow release of cisplatin, which may be due to formation of strong bond between cisplatin and dendrimer. This study will contribute to create a fine print for the formulation development of PAMAM dendrimer–cisplatin complexes.     

Development of a cyclodextrin-based nasal delivery system for lorazepam

A new drug delivery system containing hydroxypropyl-beta-cyclodextrin (HP-beta-CD) and a mucoadhesive polymer was developed with the aim to overcome the limitations connected with the nasal application of drugs with low water solubility. Lorazepam, free or as cyclodextrin inclusion complex, was loaded into mucoadhesive microparticles by spray drying, using hydroxypropylmethyl cellulose (HPMC), carbomer, and HPMC/carbomer interpolymer complex (IPC) as mucoadhesive components. Differential scanning calorimetry (DSC) indicated the presence of drug crystalline areas in microparticles loaded with free lorazepam, whereas in those loaded with HP-beta-CD inclusion complex, the drug was amorphous. Zeta potential measurement revealed that the polymer was the main component on the surface of the microparticles. The swelling rate and mucoadhesive properties of the microparticles were determined by the polymer type used in formulation. IPC- and carbomer-based microparticles showed superior swelling rate and mucoadhesion compared with the HPMC-based microparticles (p < .05). Drug loading into the polymer matrix decreased the swelling rate as well as the mucoadhesive properties of microparticles (p < .05), whereas the presence of HP-beta-CD in the matrix did not induce any additional reduction of those parameters (p > .05). The in vitro dissolution studies demonstrated that the microparticles containing the lorazepam inclusion complex displayed 1.8-2.5 times faster drug release compared with those containing free lorazepam. The change in the drug release rate could be connected with improved drug solubility inside the polymer matrix due to inclusion complex formation, as well as to the reduction in crystallinity following complexation, as confirmed by DSC studies.     

Inhibition of 3‐D Tumor Spheroids by Timed‐Released Hydrophilic and Hydrophobic Drugs from Multilayered Polymeric Microparticles

First‐line cancer chemotherapy necessitates high parenteral dosage and repeated dosing of a combination of drugs over a prolonged period. Current commercially available chemotherapeutic agents, such as Doxil and Taxol, are only capable of delivering single drug in a bolus dose. The aim of this study is to develop dual‐drug‐loaded, multilayered microparticles and to investigate their antitumor efficacy compared with single‐drug‐loaded particles. Results show hydrophilic doxorubicin HCl (DOX) and hydrophobic paclitaxel (PTX) localized in the poly(dl ‐lactic‐co‐glycolic acid, 50:50) (PLGA) shell and in the poly(l ‐lactic acid) (PLLA) core, respectively. The introduction of poly[(1,6‐bis‐carboxyphenoxy) hexane] (PCPH) into PLGA/PLLA microparticles causes PTX to be localized in the PLLA and PCPH mid‐layers, whereas DOX is found in both the PLGA shell and core. PLGA/PLLA/PCPH microparticles with denser shells allow better control of DOX release. A delayed release of PTX is observed with the addition of PCPH. Three‐dimensional MCF‐7 spheroid studies demonstrate that controlled co‐delivery of DOX and PTX from multilayered microparticles produces a greater reduction in spheroid growth rate compared with single‐drug‐loaded particles. This study provides mechanistic insights into how distinctive structure of multilayered microparticles can be designed to modulate the release profiles of anticancer drugs, and how co‐delivery can potentially provide better antitumor response.     

Development of a Cyclodextrin-Based Nasal Delivery System for Lorazepam

A new drug delivery system containing hydroxypropyl-β-cyclodextrin (HP-β-CD) and a mucoadhesive polymer was developed with the aim to overcome the limitations connected with the nasal application of drugs with low water solubility. Lorazepam, free or as cyclodextrin inclusion complex, was loaded into mucoadhesive microparticles by spray drying, using hydroxypropylmethyl cellulose (HPMC), carbomer, and HPMC/carbomer interpolymer complex (IPC) as mucoadhesive components. Differential scanning calorimetry (DSC) indicated the presence of drug crystalline areas in microparticles loaded with free lorazepam, whereas in those loaded with HP-β-CD inclusion complex, the drug was amorphous. Zeta potential measurement revealed that the polymer was the main component on the surface of the microparticles. The swelling rate and mucoadhesive properties of the microparticles were determined by the polymer type used in formulation. IPC- and carbomer-based microparticles showed superior swelling rate and mucoadhesion compared with the HPMC-based microparticles (p < .05). Drug loading into the polymer matrix decreased the swelling rate as well as the mucoadhesive properties of microparticles (p < .05), whereas the presence of HP-β-CD in the matrix did not induce any additional reduction of those parameters (p > .05). The in vitro dissolution studies demonstrated that the microparticles containing the lorazepam inclusion complex displayed 1.8–2.5 times faster drug release compared with those containing free lorazepam. The change in the drug release rate could be connected with improved drug solubility inside the polymer matrix due to inclusion complex formation, as well as to the reduction in crystallinity following complexation, as confirmed by DSC studies.     

Cross-linked cationic polymer microparticles: effect of N-trimethyl chitosan chloride on the release and permeation of ibuprofen

Microparticles made by cross-linking hydrophilic polymers, such as chitosan, have been used to modify the release rate of a loaded drug. In this study a polymer with fixed positive charges, N-trimethyl chitosan chloride (TMC), was used in combination with chitosan to formulate microparticles to investigate its effects on drug release rate and transport across intestinal epithelial cells. The microparticles were prepared by cross-linking these cationic polymer(s) using sodium citrate as the ionic cross-linker. This process was done under homogenization and ultrasonication to control the size of the particles. The addition of TMC to the chitosan microparticles resulted in an increase in particle size of the microparticles and an increase in ibuprofen release rate as compared to the microparticles containing chitosan alone. Permeation of ibuprofen across Caco-2 cell monolayers, after administration of a suspension of the microparticles to the apical side, was not significantly different for the microparticles containing TMC as compared to those consisting of chitosan alone. It was concluded that release of TMC molecules from the microparticles was probably not sufficient to interact with the intestinal epithelial cells in order to change the permeation of the released drug.     

Quercetin loading on mesoporous magnetic MnFe2O4@ hydroxyapatite core-shell nanoparticles for treating cancer cells

Despite the availability of various nanostructure for cancer cells therapeutic, caring hydrophobic drugs to the target site is still one of the great challenges in chemotherapy. In this study, quercetin (QC), a poorly water-soluble natural anticancer agent, was used as a model drug to evaluate the efficiency of mesoporous magnetic MnFe₂O₄ core-shell nanocomposite particles. A simple co-precipitation method was employed to synthesis MnFe₂O₄ as core of nanostructure. Then, the obtained MnFe₂O₄ nanoparticles were coated with mesoporous hydroxyapatite (HA) shell as a new perspective for drug loading. The magnetic mesoporous nanostructure had specific surface area and mean pore size of 165.44 m²/g and 11.561 nm, respectively. In QC loading process, the MnFe₂O₄@HA nanostructure demonstrated loading capacity of 123 µg/mg with pH-depended release manner. In compare with free QC, loaded QC on MnFe₂O₄ core-shell nanocomposite particles exhibited 55% higher antioxidant activities against free 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals. Moreover, comparative in-vitro anticancer studies on Michigan cancer foundation (MCF)-7 cells, breast cancer cell line, demonstrated more reduction in number of viable cells (35.6%) using loaded QC than that of free QC (50.76%), suggesting improvement in the solubility of QC by loading onto mesoporous magnetic nanocomposite particles compared to free QC.     

Corrosion‐Activated Chemotherapeutic Function of Nanoparticulate Platinum as a Cisplatin Resistance‐Overcoming Prodrug with Limited Autophagy Induction

Despite nanoparticulate platinum (nano‐Pt) has been validated to be acting as a platinum‐based prodrug for anticancer therapy, the key factor in controlling its cytotoxicity remains to be clarified. In this study, it is found that the corrosion susceptibility of nano‐Pt can be triggered by inducing the oxidization of superficial Pt atoms, which can kill both cisplatin‐sensitive/resistance cancer cells. Direct evidence in the oxidization of superficial Pt atoms is validated to observe the formation of platinum oxides by X‐ray absorption spectroscopy. The cytotoxicity is originated from the dissolution of nano‐Pt followed by the release of highly toxic Pt ions during the corrosion process. Additionally, the limiting autophagy induction by nano‐Pt might prevent cancer cells from acquiring autophagy‐related drug resistance. With such advantages, the possibility of further autophagy‐related drug resistance could be substantially reduced or even eliminated in cancer cells treated with nano‐Pt. Moreover, nano‐Pt is demonstrated to kill cisplatin‐resistant cancer cells not only by inducing apoptosis but also by inducing necrosis for pro‐inflammatory/inflammatory responses. Thus, nano‐Pt treatment might bring additional therapeutic benefits by regulating immunological responses in tumor microenvironment. These findings support the idea that utilizing nano‐Pt for its cytotoxic effects might potentially benefit patients with cisplatin resistance in clinical chemotherapy.     

Preparation and optimization of monodisperse polymeric microparticles using modified vibrating orifice aerosol generator for controlled delivery of letrozole in breast cancer therapy

Abstract

Letrozole (LTZ) is effective for the treatment of hormone-receptor-positive breast cancer in postmenopausal women. In this work, and for the first time, using vibrating orifice aerosol generator (VOAG) technology, monodisperse poly-ε-caprolactone (PCL), and poly (D, L-Lactide) (PDLLA) LTZ-loaded microparticles were prepared and found to elicit selective high cytotoxicity against cancerous breast cells with no apparent toxicity on healthy cells in vitro. Plackett–Burman experimental design was utilized to identify the most significant factors affecting particle size distribution to optimize the prepared particles. The generated microparticles were characterized in terms of microscopic morphology, size, zeta potential, drug entrapment efficiency, and release profile over one-month period. Long-term cytotoxicity of the microparticles was also investigated using MCF-7 human breast cancer cell lines in comparison with primary mammary epithelial cells (MEC). The prepared polymeric particles were monodispersed, spherical, and apparently smooth, regardless of the polymer used or the loaded LTZ concentration. Particle size varied from 15.6 to 91.6?µm and from 22.7 to 99.6?µm with size distribution (expressed as span values) ranging from 0.22 to 1.24 and from 0.29 to 1.48 for PCL and PDLLA based microparticles, respectively. Upon optimizing the manufacture parameters, span was reduced to 0.162–0.195. Drug entrapment reached as high as 96.8%, and drug release from PDLLA and PCL followed a biphasic zero-order release using 5 or 30% w/w drug loading in the formulations. Long-term in vitro cytotoxicity studies indicated that microparticles formulations significantly inhibited the growth of MCF-7 cell line over a prolonged period of time but did not have toxic effects on the normal breast epithelial cells.     

Preparation of Monodisperse Biodegradable Polymer Microparticles Using a Microfluidic Flow‐Focusing Device for Controlled Drug Delivery

Degradable microparticles have broad utility as vehicles for drug delivery and form the basis of several therapies approved by the US Food and Drug Administration. Conventional emulsion‐based methods of manufacturing produce particles with a wide range of diameters (and thus kinetics of release) in each batch. This paper describes the fabrication of monodisperse, drug‐loaded microparticles from biodegradable polymers using the microfluidic flow‐focusing (FF) devices and the drug‐delivery properties of those particles. Particles are engineered with defined sizes, ranging from 10 µm to 50 µm. These particles are nearly monodisperse (polydispersity index = 3.9%). A model amphiphilic drug (bupivacaine) is incorporated within the biodegradable matrix of the particles. Kinetic analysis shows that the release of the drug from these monodisperse particles is slower than that from conventional methods of the same average size but a broader distribution of sizes and, most importantly, exhibit a significantly lower initial burst than that observed with conventional particles. The difference in the initial kinetics of drug release is attributed to the uniform distribution of the drug inside the particles generated using the microfluidic methods. These results demonstrate the utility of microfluidic FF for the generation of homogenous systems of particles for the delivery of drugs.     

Mesoporous silica particles induce size dependent effects on human dendritic cells

The effects of mesoporous silica nano- (270 nm) and microparticles (2.5 microm) with surface areas above 500 m2/g were evaluated on human monocyte-derived dendritic cells (MDDC). Size- and concentration-dependent effects were seen where the smaller particles and lower concentrations affected MDDC to a minor degree compared to the larger particles and higher concentrations, both in terms of viability, uptake, and immune regulatory markers. Our findings support the further development of mesoporous silica particles in drug and vaccine delivery systems.     

Preparation and in vitro characteristics of lactoferrin-loaded chitosan microparticles

In order to achieve the delivery and controlled release of lactoferrin (LF), a biologically multifunctional protein, chitosan microparticles loaded with LF were prepared. Several types of chitosan microparticles containing LF were prepared by the w/o emulsification-solvent evaporation method, and the particle characteristics and release properties in JP 2nd fluid, pH 6.8, were examined. All kinds of microparticles were obtained at a yield of more than 75% (w/w). LF-loaded microparticles prepared by nonsonication and nonaddition of sulfate, named Ch-LF(N), showed high drug content, small particle size and spherical particle shape. Also, for release properties, Ch-LF(N) exhibited gradual drug release over 7 hr with less remaining in the microparticles. Considering the mucoadhesive properties of chitosan microparticles, Ch-LF(N) are suggested to be useful for gradual supply to topical diseased sites or for effective delivery to intestinal areas with abundant LF receptors.     

盐酸小檗碱/介孔二氧化硅载体的制备与缓释行为研究

采用水热合成法制备了SBA-15和SBA-16两种介孔SiO₂载体材料,利用浸渍法将盐酸小檗碱(BBH)原料药负载于载体上,制备了载药BBH/SBA-15和BBH/SBA-16。通过多种表征方法对载药后材料的晶体结构、孔道结构等进行了测试,并研究了材料的载药、释药规律。结果表明,SBA-15和SBA-16的载药量分别为13.50%和3.45%。与BBH原料药相比,两种介孔SiO₂载体均能够延长药物的释放,具有缓释效果。但SBA-15的孔径(5.77nm)较大,释药存在突释现象;而SBA-16的孔径(3.95nm)较小,能够缓慢释放药物。     

Study of mesoporous silica/magnetite systems in drug controlled release

Ordered mesoporous materials like SBA-15 have a network of channels and pores with well-defined size in the nanoscale range. This particular silica matrix pore architecture makes them suitable for hosting a broad variety of compounds in very promising materials in a range of applications, including drug release magnetic carriers. In this work, magnetic nanoparticles embedded into mesoporous silica were prepared in two steps: first, magnetite was synthesized by oxidation-precipitation method, and next, the magnetic nanoparticles were coated with mesoporous silica by using nonionic block copolymer surfactants as structure-directing agents. The materials were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), N(2) adsorption, and scanning electron microscopy (SEM). The influence of magnetic nanoparticles on drug release kinetics was studied with cisplatin, carboplatin, and atenolol under in vitro conditions in the absence and in the presence of an external magnetic field (0.25 T) by using NdFeB permanent magnet. The constant external magnetic field did not affect drug release significantly. The low-frequency alternating magnetic field had a large influence on the cisplatin release profile.     

Preparation and In Vitro Characteristics of Lactoferrin-loaded Chitosan Microparticles

ABSTRACT

In order to achieve the delivery and controlled release of lactoferrin (LF), a biologically multifunctional protein, chitosan microparticles loaded with LF were prepared. Several types of chitosan microparticles containing LF were prepared by the w/o emulsification-solvent evaporation method, and the particle characteristics and release properties in JP 2nd fluid, pH 6.8, were examined. All kinds of microparticles were obtained at a yield of more than 75% (w/w). LF-loaded microparticles prepared by nonsonication and nonaddition of sulfate, named Ch-LF(N), showed high drug content, small particle size and spherical particle shape. Also, for release properties, Ch-LF(N) exhibited gradual drug release over 7 hr with less remaining in the microparticles. Considering the mucoadhesive properties of chitosan microparticles, Ch-LF(N) are suggested to be useful for gradual supply to topical diseased sites or for effective delivery to intestinal areas with abundant LF receptors.     

Self-assembled mesoporous carbon films for platinum metal catalyst loading

This work demonstrates the use of self-assembled carbon films in designing fuel cell electrode. Well-dispersed mesoporous carbon particles were prepared based on the spontaneous and strong chemisorption of polyoxometalate (POM) solution on carbon surface. Electrostatically self-assembled films of the POM stabilized carbon interlaced with cationic polyelectrolyte binding layer were useful for confining electrodeposition of platinum (Pt) catalyst. The structure and morphology of the resulting films were characterized by X-ray diffraction and scanning electron microscopy respectively. The electrocatalytic activities of Pt deposited on the self-assembled carbon films toward the degradation of small organic molecules are largely dependent on the quantity of Pt and carbon. This work represents a simply controlled test-bed for fundamental studies on loading metal catalysts on ordered mesoporous carbon films for catalysis.     

Accelerated ketoprofen release from spray-dried polymeric particles: importance of phase transitions and excipient distribution

HPMC-, PVPVA- and PVP-based microparticles loaded with 30% ketoprofen were prepared by spray drying suspensions or solutions in various water:ethanol blends. The inlet temperature, drying gas and feed flow rates were varied. The resulting differences in the ketoprofen release rates in 0.1?M HCl could be explained based on X-ray diffraction, mDSC, SEM and particle size analysis. Importantly, long term stable drug release could be provided, being much faster than: (i) drug release from a commercial reference product, (ii) the respective physical drug:polymer mixtures, as well as (iii) the dissolution of ketoprofen powder as received. In addition, highly supersaturated release media were obtained, which did not show any sign for re-crystallization during the observation period. Surprisingly, spraying suspensions resulted in larger microparticles exhibiting faster drug release compared to spraying solutions, which resulted in smaller particles exhibiting slower drug release. These effects could be explained based on the physico-chemical characteristics of the systems.     

Cellular Association and Assembly of a Multistage Delivery System

The realization that blood‐borne delivery systems must overcome a multiplicity of biological barriers has led to the fabrication of a multistage delivery system (MDS) designed to temporally release successive stages of particles or agents to conquer sequential barriers, with the goal of enhancing delivery of therapeutic and diagnostic agents to the target site. In its simplest form, the MDS comprises stage‐one porous silicon microparticles that function as carriers of second‐stage nanoparticles. Cellular uptake of nontargeted discoidal silicon microparticles by macrophages is confirmed by electron and atomic force microscopy (AFM). Using superparamagnetic iron oxide nanoparticles (SPIONs) as a model of secondary nanoparticles, successful loading of the porous matrix of silicon microparticles is achieved, and retention of the nanoparticles is enhanced by aminosilylation of the loaded microparticles with 3‐aminopropyltriethoxysilane. The impact of silane concentration and reaction time on the nature of the silane polymer on porous silicon is investigated by AFM and X‐ray photoelectron microscopy. Tissue samples from mice intravenously administered the MDS support co‐localization of silicon microparticles and SPIONs across various tissues with enhanced SPION release in spleen, compared to liver and lungs, and enhanced retention of SPIONs following silane capping of the MDS. Phantom models of the SPION‐loaded MDS display negative contrast in magnetic resonance images. In addition to forming a cap over the silicon pores, the silane polymer provides free amines for antibody conjugation to the microparticles, with both VEGFR‐2‐ and PECAM‐specific antibodies leading to enhanced endothelial association. This study demonstrates the assembly and cellular association of a multiparticle delivery system that is biomolecularly targeted and has potential for applications in biological imaging.