Jose M. Rivera

Jose M. Rivera
University of Puerto Rico at Rio Piedras | UPR-RP · Department of Chemistry

Ph.D.

About

48
Publications
2,084
Reads
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976
Citations
Citations since 2016
10 Research Items
268 Citations
20162017201820192020202120220102030405060
20162017201820192020202120220102030405060
20162017201820192020202120220102030405060
20162017201820192020202120220102030405060
Additional affiliations
August 2002 - present
University of Puerto Rico at Rio Piedras
Position
  • Professor (Full)
Education
August 1995 - May 2000
Massachusetts Institute of Technology
Field of study
  • Organic Chemistry

Publications

Publications (48)
Preprint
The encapsulation of therapeutic agents, like drugs and vaccines, into colloidal particles, offers an attractive strategy to enhance their efficacy. Previously, we reported the development of guanosine-based supramolecular colloidal particles suitable for encapsulating a broad array of guests ranging from small molecule drugs, like doxorubicin, to...
Preprint
Full-text available
The encapsulation of therapeutic agents, like drugs and vaccines, into colloidal particles, offers an attractive strategy to enhance their efficacy. Previously, we reported the development of guanosine-based supramolecular colloidal particles suitable for encapsulating a broad array of guests ranging from small molecule drugs, like doxorubicin, to...
Article
Full-text available
Immunogenicity of DNA vaccines can be efficiently improved by adding adjuvants into their formulations. In this regard, the application of nano- and microparticles as vaccines adjuvants, or delivery systems, provides a powerful tool in designing modern vaccines. In the present study, we examined the role of “Supramolecular Hacky Sacks” (SHS) partic...
Article
Full-text available
Most drugs are small molecules because of their attractive pharmacokinetics, manageable development and manufacturing, and effective binding into the concave crevices of bio-macromolecules. Despite these features, they often fall short when it comes to effectively recognizing the surfaces of bio-macromolecules. One way to overcome the challenge of...
Article
Guanosine and related derivatives self-assemble in the presence of cations like potassium into supramolecular G-quadruplexes (SGQs), where four guanine moieties form planar tetrads (T) that coaxially stack into columnar aggregates with broad size distributions. However, SGQs made from 8-aryl-2'-deoxyguanosine derivatives (8ArGs), form mostly octame...
Article
Full-text available
We report the synthesis and self-assembly of two lipophilic 2'-deoxyguanosine (G) derivatives whose fluorescence intensity is modulated by self-assembly into supramolecular G-quadruplexes (SGQs). Whereas both derivatives self-assemble isostructurally, one shows up to 100% emission enhancement while the other shows an initial enhancement, followed b...
Article
Self-assembly is a powerful tool for the construction of complex nanostructures. Despite the advances in the field, the development of precise self-assembled structures remains a challenge. We have shown that in the presence of suitably sized cations like K+, 8-aryl-2'-deoxyguanosine (8ArG) derivatives self-assemble into sets of coaxially stacked p...
Article
Nanoflowers (NFs) are flowered-shaped particles with overall sizes or features in the nano-scale. Beyond their pleasing aesthetics, NFs have found a number of applications ranging from catalysis, sensing to drug delivery. Compared to inorganic based NFs, their organic and hybrid counterparts are relatively underdeveloped mostly because of the lack...
Article
Full-text available
Supramolecular G-quadruplexes (SGQs) are formed via the cation promoted self-assembly of guanine derivatives into stacks of planar hydrogen-bonded tetramers. Here, we present results on the formation of SGQs made from the 8-(m-acetylphenyl)-2′-deoxyguanosine (mAGi) derivative in the presence of various mono- and divalent cations. NMR and HR ESI-MS...
Article
Thermoresponsive systems are attractive due to their suitability for fundamental studies as well as their practical uses in a wide variety of applications. While much progress have been achieved using polymers, alternative strategies such as the use of well-defined non-polymeric supramolecules are still underdeveloped. Here we report three 8-aryl-2...
Article
Photoirradiation of a hexadecameric supramolecular G-quadruplex leads to a diastereoselective [2 + 2] cyclodimerization of half of its constituent subunits, which in turn shifts the equilibrium toward the formation of a precise heteromeric octamer.
Article
We describe precise supramolecules that enable the evaluation of the effective hydrophobicity of amphiphilic or "patchy" nanoglobular systems. These supramolecules exhibit the lower critical solution temperature phenomenon, which provides a quantitative measure of their effective hydrophobicity. Specifically, two isomeric 8-aryl-2'-deoxyguanosine d...
Article
Full-text available
We describe the synthesis of a fluorescent deoxyguanosine derivative that co-assembles (in water) with an unlabeled analogue into a heteromeric supramolecular G-quadruplex, which forms a host-guest complex with doxorubicin as evidenced by FRET experiments.
Conference Paper
Guanosine forms planar tetramers known as G-tetrads which can further stack and yield supramolecules known as G-quadruplexes (GQs). The main goal is to design reliable GQ-nanostructures with different molecularity (e.g., octamers, dodecamers, hexadecamers) for their use in applications as self-assembled drugs, dendrimers, or cellular imaging probes...
Article
Full-text available
We report the metallo-responsive high fidelity switching between hexadecameric and octameric supramolecular G-quadruplexes triggered by a change in the metal cation promoter from potassium to strontium, respectively.
Article
We have developed the 8-(m-acetylphenyl)-2'-deoxyguanosine (mAG) scaffold for the self-assembly of supramolecules in water and for the synthesis of self-assembled dendrimers (SADs) in organic media. Previously, reported mAG assemblies showed promising characteristics for the construction of SADs. Yet, none of these SADs had large enough dendrons to...
Article
Full-text available
We have previously reported that 8-phenyl-2'-deoxyguanosine derivatives (8PhGs) are able to extract metal cations from an aqueous phase into an organic phase. Herein we report on the ability of 8PhGs to transport metal cations across a bulk lipophilic liquid membrane. The experiments were performed using lithium, sodium, potassium, and strontium pi...
Article
Full-text available
An 8-(phenyl)-2'-deoxyguanosine derivative self-assembles in aqueous media into discrete hexadecamers that further self-assemble above 32 °C into microglobules that encapsulate the drug doxorubicin.
Article
Here we show 2'-deoxyguanosine derivatives that self-assemble in aqueous media into discrete supramolecular hexadecamers and exhibit the lower critical solution temperature (LCST) phenomenon. Spectroscopic, calorimetric, and electron microscopy studies support the fact that above the transition temperature (T(t)) the supramolecules further assemble...
Conference Paper
Guanosine is a self-complementary nucleoside that forms planar tetramers known as G-tetrads. Further stacking of these, aided by the complexation of metal cations, yield supramolecules known as G-quadruplexes (GQs). The solvent, anions, templating metal cation, and structural modifications of the monomeric subunits affect the supramolecular propert...
Conference Paper
Dendrimers are monodisperse polymers with unique globular shape where all repeating units or branching pattern emerge radially from a central core. We will present the construction and preliminary encapsulation studies of water-soluble and discrete self-assembled dendrimers (SADs) using dendronized 8-(m-acetylphenyl)-2'-deoxyguanosine (mAG) scaffol...
Conference Paper
Smart materials can sense environmental changes and respond to them accordingly. In the case of thermosensitive materials, when an increase in temperature induces a phase separation or precipitate the system is said to have a Lower Critical Solution Temperature (LCST). Besides being a curious phenomenon, this inverse temperature solubility is a ver...
Conference Paper
The development of self-assembled discrete structures of intermediate molecularity remains a challenge that must be overcome if self-assembly is to become a viable tool for the construction of bio and nanomaterials. A full understanding of the interactions among the individual subunits must be obtain in order to fully control the outcome of the sel...
Conference Paper
G-quadruplexes (GQs) are formed through the self-assembly of guanine bases to form planar hydrogen-bonded tetramers that stack on each other, templated by a metal cation. The cation, the anion and/or the solvent can modulate the thermodynamic and kinetic stability of such GQs. We will present results on the formation of GQs made from 8-Aryl-2'-deox...
Conference Paper
Synthesis and Supramolecular Properties of Fluorescent 8-Chalcone-2-deoxyguanosine Derivatives Diana Silva Brenes & Jos M. Rivera University of Puerto Rico at Ro Piedras, College of Natural Sciences, Department of Chemistry, San Juan, Puerto Rico 00931 dianavsilva@gmail.com, jmrivortz@mac.com Recently we have reported the construction of discrete a...
Conference Paper
Self-assembly offers a convenient strategy for the development of multifunctional nanostructures. Our group has developed a series of 8-aryl-2'-deoxyguanosine (8ArG) mononucleoside derivatives, which are useful in the construction of self-assembled dendrimers (SADs) in organic and aqueous media. Such dendrimers are composed of sixteen subunits held...
Article
Controlling the properties of self-assembled supramolecules via intrinsic parameters (i.e., structural information in the subunits) enables the reliable construction of assemblies of well-defined size and composition. Here we show that an optimum balance between repulsive (e.g., steric) and attractive (e.g., pi-pi, dipole-dipole) noncovalent intera...
Article
Full-text available
Here we show the reversible high fidelity switching between two discrete self-assembled supramolecules made from a lipophilic 8-phenyl-2'-deoxyguanosine derivative induced by an indirect solvent effect. A hexadecameric supramolecule containing four stacked tetramers is formed in acetonitrile aided by higher potassium concentrations. When the amount...
Article
Full-text available
We report the self-assembly of a hydrophilic 8-(m-acetylphenyl)-2'-deoxyguanosine (mAG) derivative into a discrete and thermally stable hexadecameric supramolecule in aqueous media. We demonstrate that this hexadecamer is isostructural to the one formed by a related lipophilic derivative in organic media. This mAG moiety represents a rare example o...
Article
Herein we describe the construction of hexadecameric self-assembled dendrimers (SADs) using a series of dendronized 8-(m-acetylphenyl)-2'-deoxyguanosine (mAG) subunits. The azido-substituted mAG subunits were covalently linked to alkynyl polyester dendrons using a copper-catalyzed 1,3-dipolar cycloaddition reaction. Discrete SADs are formed with hi...
Article
Full-text available
We describe the synthesis of 8-heteroaromatic-2'-deoxyguanosine analogues using Suzuki-Miyaura or Stille conditions. Unprotected and protected 8-bromo-2'-deoxyguanosine was coupled with commercially available heteroarylboronic acids or the trialkyltin derivatives of 2-pyridylbromides either with or without microwave irradiation in good yields.
Article
Full-text available
Guanine and G-rich oligonucleotides are known to self-assemble in the presence of a variety of cations to form higher ordered structures known as Gquadruplexes. We have synthesized a library of 8-aryl/heteroaryl-2'-deoxyguanosine derivatives (8ArGs) that are also able to self-assemble into quadruplex structures. We demonstrate that the properties o...
Article
Novel base-modified G-analogues act as self-assembled ionophores for various metal cations. Their extracting efficiency can be modulated by the presence and substitution pattern of a functionalized phenyl group that replaces the H8 in the guanine base.
Article
Full-text available
Extended abstract of a paper presented at Microscopy and Microanalysis 2005 in Honolulu, Hawaii, USA, July 31--August 4, 2005.
Article
[structure: see text] The synthesis and self-assembling properties of 8-aryl-2'-deoxyguanosine derivatives are described. Our studies suggest that a properly placed acetyl group can increase the stability and specificity of the resulting G-quadruplex supramolecules by enhancing noncovalent interactions such as hydrogen bonds and pi-stacking.
Article
Studies on the different congeners of the softball were undertaken to explore structural variants for enantioselective encapsulation. Two different spacer elements in the monomeric subunit render the dimeric softball chiral although the monomer itself is achiral. The dimers represent capsules with dissymmetric cavities with volumes ranging from 190...
Article
Achiral building blocks form nonracemic, chiral capsular hosts with enantioselective molecular recognition properties. The chirality is imprinted by a chiral guest template, and persists for hours in organic solvents after the guest has been removed. The exchange equilibria are depicted, with the guest exchanges shown by the horizontal equilibria a...
Article
Reversibly self-assembling host–guest complexes of the softball type are characterized by electrospray ionization mass spectrometry. Quaternary ammonium ions serve simultaneously as guests and ion labels. Isotope pattern analysis, inclusion of labeled guests, heterodimer experiments, size and shape dependence, and collision-induced fragmentation re...
Article
Full-text available
Molecules with self-complementary surfaces interact through weak intermolecular forces to form assemblies, and the assembled states frequently exhibit distinctive properties. Described here are systems in which symmetrical molecules assemble through hydrogen bonding to produce capsules with dissymmetric cavities. The capsules form and dissipate on...
Article
Molecules with self-complementary surfaces interact through weak intermolecular forces to form assemblies, and the assembled states frequently exhibit distinctive properties. Described here are systems in which symmetrical molecules assemble through hydrogen bonding to produce capsules with dissymmetric cavities. The capsules form and dissipate on...

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