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TRACK 6 TRACK 6 Technical Program

modification, and robust optical properties. While drug molecules can be moiety, selectively based on the combinatorial approach and conjugated to
covalently immobilized on the nanoparticles’ surface, non-covalent interac- discoidal silicon mesoporous particles (SMP) nanovectors. ESTA-SMP and
tions are particularly appealing because they minimize modification of the CD44TA-SMP were tested in vitro for targeting human macrophages infect-
drug molecules, whose efficacy is then largely retained upon release. In ed with M.smegmatis, M.avium and M.tuberculosis were analyzed for the
this work, we have developed a controlled-release system for delivery of particle uptake, resulting macrophage mortality, and the cytokine release.
antibiotics based on gold nanoconstructs and demonstrated the synergistic Further, the formulations were tested on balb/c mice pre-infected with M.
effect of photothermal and antibiotic therapies. The gold nanoconstructs tuberculosis for 14 days, and mice were sacrificed 2 hour and 8 hours after
are capable of converting light into heat and triggering the release of the treatment. Silicon particle disposition was analyzed by inductively coupled
encapsulated antibiotics. Upon light irradiation, the photothermal effect of plasma atomic emission spectroscopy (AES-ICP) as well as by fluorescence
gold nanoconstructs can initiate an instantaneous release, and thus control microscopy of tissue sections. Colony forming units (CFU) of M. tuberculosis
of the release kinetics, demonstrating on-demand drug release. The surface were assessed by growing tissue homogenized on Middlebrook 7H11 agar
of these gold nanoconstructs can be readily functionalized with specific plates and counting after 2 weeks of growth.
moieties for targeting biomarkers at the pathological sites. We have demon-
strated that an appropriate antibiotic (daptomycin) can be incorporated into In vitro, the uptake and killing efficacy increased along with increasing
gold nanoconstructs and that daptomycin-loaded gold nanoconstructs can pathogenicity of Mycobacterium strains. 40 and 25 pSi-ESTA and pSi-CD-
be conjugated to antibodies targeting a species-specific surface protein 44TA were taken up, respectively, by M. tuberculosis-infected macrophages.
(staphylococcal protein A) as a means of achieving selective delivery of the In control macrophages and M. smegmatis-infected macrophages, the
nanoconstructs directly to the bacterial cell surface. We demonstrated that numbers were significantly lower, ranging below 10, while M. avium-infected
laser irradiation at levels within the current safety standard for use in humans macrophages ingested around 10 and 15 particles. Higher number of ingest-
can be used to achieve both a lethal photothermal effect and controlled ed particles led to higher cell death, where less than 50% of M. tuberculo-
release of the antibiotic, thus resulting in a degree of therapeutic synergy sis- and M. avium-infected macrophages survived the treatment with both
capable of eradicating viable bacteria. The use of this nanoconstruct to syn- formulations. Furthermore, in vivo results showed a 4-fold and almost 2-fold
ergize these therapeutic modalities was successfully demonstrated for the accumulation of pSi-ESTA and pSi-CD44TA in the lung of infected mice, but
methicillin-sensitive S. aureus strain UAMS-1 in planktonic culture and more no increased accumulation in uninfected mice. Further analysis of the lung
importantly for the methicillin-resistant S. aureus strain LAC in both plank- tissue also revealed an increased T-cell accumulation with the treatment,
tonic culture and a clinically-relevant biofilm model. The system was initially where 2-times and 4-times amount of T-cells were found in pSi-ESTA- and
validated using planktonic bacterial cultures and was subsequently shown to pSi-CD44TA-treated lung of infected mice after 8 hours, respectively, when
be effective in the context of an established biofilm, thus indicating that this compared to the control infected mice. Additionally, the treatment, even
approach could be used to resolve intrinsically-resistant biofilm infections. without any drug content, was proven to be able to reduce the number of
Further utilizing the optical properties of gold nanoconstructs, these systems live M. tuberculosis found in the lung of the infected mice by 70% within 8h.
can achieve theranostics through diagnosis via gold nanoconstructs as con- The nanovectors developed in this study were proven to enhance accumu-
trast-enhanced molecular imaging and multi-modal treatment via photother- lation to alveolar macrophages based on targeting moieties and preferential
mal and antibiotic therapies. localization in the lungs based on their geometry. The mechanism of the de-
signed system may include a combination of increased uptake of particles
leading to the infected macrophage death, as well as activation of immune
Combinatorial Approach for Targeting Anti-Tuberculosis Treat- response to TA, causing an increased T-cell accumulation in the treated
ment via Geometry-Based Nanovectors and Thioaptamers lungs. Ongoing studies with TA-SMP with anti-TB agents can open new ave-
nues in the TB management. This can potentially reduce the length of treat-
ment and increasing the drug concentration, thus avoiding multi-drug-resis-
Poster Presentation. NEMB2016-6148 tance due to long-term exposure to antibiotics.

Fransisca Leonard, Ngan Ha, Houston Methodist Research Insti-
tute, Houston, TX, United States, Preeti Sule, Texas A&M Health Mathematical Modeling for Dual Ligand Conjugated Micro/Nano
Science Center, Bryan, TX, United States, Jenolyn F. Alexander, Particle Adhesion for Targeted Drug Delivery
Houston Methodist Research Institute, Houston, TX, United States,
David E. Volk, Ganesh L. R. Lokesh, University of Texas Health Poster Presentation. NEMB2016-6135
Science Center at Houston, Houston, TX, United States, Jeffrey D.
Cirillo, Texas A&M Health Science Center, Bryan, TX, United States, Jung Hyun Yoon, Yonsei University, Wonju-si, Korea (Republic), Sei
David G. Gorenstein, University of Texas Health Science Center at Young Lee, Yonsei University, Wonju, Korea (Republic)
Houston, Houston, TX, United States, Edward A. Graviss, Biana
Godin, Houston Methodist Research Institute, Houston, TX, United Drug delivery system based on micro/nano particles is one of the promising
States techniques for targeting cardiovascular diseases or cancers (Ferrari, 2005).
To avoid side effects and toxicities of the drug, it is important for the particles
Tuberculosis (TB) remains the most frequent and important infectious dis- to be attached to the diseased cells specifically. To enhance the efficiency
ease causing morbidity and death worldwide. One-third of world’s popula- and specificity of the drug delivery, many studies on the surface modified
tion is infected with Mycobacterium tuberculosis (MTB), the etiologic agent particle have been performed by several research groups through attaching
of TB, which usually resides in the alveolar macrophages. The major prob- adhesion-related ligand or antibody (Farokhzad et al., 2004, 2005, Paulis et
lem in eradicating TB is caused by the ability of Mycobacterium to survive al., 2012, Kolhar et al., 2013). The ligands conjugated onto the surface of the
and replicate inside macrophage phagosomes, and current tuberculosis particle specifically bind to their receptors expressed on the inflammatory
treatment regimen requires at least 6 months of chemotherapy. The long cells. Moreover, multiple molecules are expressed on the diseased cell and
course of treatment causes low compliance and often leads to the selection it is possible to choose several adhesion-related molecules for targeting.
of multidrug resistant strains. The scientific community generally agrees For example, for leukocyte binding to the inflammatory endothelium, the ad-
that the key to improving TB therapy relies on shortening its duration and hesion procedure is related to two types of molecule, i.e. ICAM and selectin
making it more effective. In this study we propose for the first time, that he- family. Thus, dual ligand-receptor interaction model for the specific targeting
modynamics in the lung and the pathological changes in the infected cells of the particle to the cell needs to be considered for particulate system
and inflamed vascular structures result in the alteration of the macrophage/ design. The stochastic approach of the adhesion of two different ligands
vascular endothelium phenotype (e.g., surface receptor expression), causing conjugated particle to the cell under the hydrodynamic flow is derived math-
the selective targeting of the nanovectors to the infected tissue. ematically, assuming that each ligand-receptor interacts specifically and in- 75
dependently. It is verified that there are several parameters affecting on the
We used thioaptamers (TA) with E-selectin (ESTA) and a CD44 targeting adhesion of the particle to the cell. First, a separation distance determined