Luis Quintero

University of Puerto Rico at Cayey, Cayey, Cayey, Puerto Rico

Are you Luis Quintero?

Claim your profile

Publications (9)16.6 Total impact

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Nanotechnology is playing an increasing role in targeted drug delivery into pathological tissues. Drug-loaded pharmaceutical nanocarriers can be delivered into diseased sites by passive targeting (spontaneous accumulation of nanocarriers in the areas with affected vasculature) or by active targeting (via site-specific ligands attached to the surface of drug-loaded nanocarriers). Subsequent level of targeting requires cellular internalization of nanocarriers and their specific association with certain individual cell organelles. The control over intracellular distribution of pharmaceutical nanocarriers requires effective and noninvasive methods of their visualization inside cells. In an attempt to enhance cellular internalization of pharmaceutical nanocarriers and their association with mitochondria specifically, we have prepared three types of cationic liposomes and investigated their intracellular distribution. The analysis was performed using Raman microspectroscopy in order to provide morphological information as well as biochemical signatures of the sample. It was demonstrated that Raman microscopy allows evaluation of the extent of mitochondrial association depending on the liposome composition.
    Molecular Pharmaceutics 02/2012; 9(4):930-6. · 4.57 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Raman spectroscopy in combination with optical microscopy provides a new non-invasive method to examine and image cellular processes. Based on the spectral parameters of a cell’s components it is possible to image cellular organelles, such as the nucleus, chromatin, mitochondria, or lipid bodies, at the resolution of conventional microscopy. Several multivariate or spectral de-mixing algorithms, for example, hierarchical cluster analysis or orthogonal subspace projection, may be used to reconstruct an image of a cell. The non-invasive character of the technique as well as the associated chemical information may offer advantages over other imaging techniques such as fluorescence microscopy. Currently of particular interest are the uptake and intracellular fate of various pharmaceutical nanocarriers, which are widely used for drug delivery purposes, including intracellular drug and gene delivery. We have imaged the uptake and distribution patterns of several carrier systems over time. In order to distinguish the species of interest from their cellular environment spectroscopically, the carrier particles or the drug load itself may be labeled with deuterium. The first part of the chapter will briefly introduce the concept of Raman imaging in combination with multivariate data analysis on some simple cell models, after which the results of the uptake studies are discussed.
    01/2011: pages 137-163;
  • 08/2010;
  • Article: BiOS
    [Show abstract] [Hide abstract]
    ABSTRACT: Noise reduction algorithms for improving Raman spectroscopy signals while preserving signal information were implemented. Algorithms based on Wavelet denoising and Kalman filtering are presented in this work as alternatives to the well-known Savitky-Golay algorithm. The Wavelet and Kalman algorithms were designed based on the noise statistics of real signals acquired using CCD detectors in dispersive spectrometers. Experimental results show that the random noise generated in the data acquisition is governed by sub-Poisson statistics. The proposed algorithms have been tested using both real and synthetic data, and were compared using Mean Squared Error (MSE) and Infinity Norm (L∞) to each other and to the standard Savitky-Golay algorithm. Results show that denoising based on Wavelets performs better in both the MSE and (L∞) the sense.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
    02/2010;
  • [Show abstract] [Hide abstract]
    ABSTRACT: Charge-Coupled Device (CCD) detectors are becoming more popular in spectroscopy instrumentation. In spite of technological advances, spurious signals and noise are unavoidable in Raman spectroscopes. In general, the noise comes from two major sources, impulsive noise caused by high energy radiation from local or extraterrestrial sources (cosmic rays), and noise produced in Raman backscattering estimation. In this work, two algorithms for impulsive noise removal are presented, based in spectral and spatial features of the noise. The algorithms combine pattern recognition and classical filtering techniques to identify the impulses. Once an impulse has been identified, it is removed and substituted with data points having similar statistical properties as the surrounding data.
    Proc SPIE 02/2010;
  • [Show abstract] [Hide abstract]
    ABSTRACT: Noise reduction algorithms for improving Raman spectroscopy signals while preserving signal information were implemented. Algorithms based on Wavelet denoising and Kalman filtering are presented in this work as alternatives to the well-known Savitky-Golay algorithm. The Wavelet and Kalman algorithms were designed based on the noise statistics of real signals acquired using CCD detectors in dispersive spectrometers. Experimental results show that the random noise generated in the data acquisition is governed by sub-Poisson statistics. The proposed algorithms have been tested using both real and synthetic data, and were compared using Mean Squared Error (MSE) and Infinity Norm (L∞) to each other and to the standard Savitky-Golay algorithm. Results show that denoising based on Wavelets performs better in both the MSE and (L∞) the sense.
    Proc SPIE 02/2010;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Novel optical imaging methods, such as Raman microspectroscopy, have been gaining recognition in their ability to obtain noninvasively the distribution of biochemical components of a sample. Raman spectroscopy in combination with optical microscopy provides a label-free method to assess and image cellular processes, without the use of extrinsic fluorescent dyes. The submicrometer resolution of the confocal Raman instrumentation allows us to image cellular organelles on the scale of conventional microscopy. We used the technique to monitor subcellular degradation patterns of two biodegradable nanocarrier systems-poly(epsilon-caprolactone) (PCL) and poly(lactic-co-glycolic acid) (PLGA). Our results suggest that both drug-delivery systems eventually are incorporated into Golgi-associated vesicles of late endosomes. These processes were monitored via the decrease of the molecule-characteristic peaks of PCL and PLGA. As the catabolic pathways proceed, shifts and variations in peak intensities and intensity ratios in the rendered Raman spectra unequivocally delineate their degradation patterns.
    ACS Nano 10/2009; 3(11):3552-9. · 12.03 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Raman spectroscopy, in combination with optical microscopy provides a new non-invasive method to asses and image cellular processes. Based on the spectral signatures of a cell's components, it is possible to image cellular organelles such as the nucleus, chromatin, mitochondria or lipid bodies, at the resolution of conventional microscopy. Several multivariate algorithms, for example hierarchical cluster analysis or orthogonal subspace projection, may be used to reconstruct an image of a cell. The noninvasive character of the technique, as well as the associated chemical information, may offer advantages over other imaging techniques such as fluorescence microscopy. Currently of particular interest are uptake and intracellular fate of various pharmaceutical nanocarriers, which are widely used for drug delivery purposes, including intracellular drug and gene delivery. We have imaged the uptake and distribution patterns of several carrier systems over time. In order to distinguish the species of interest from their cellular environment spectroscopically, the carrier particles or the drug load itself may be labeled with deuterium. Here, we introduce the concept of Raman imaging in combination with vertex component data analysis to follow the uptake of nanocarriers based on phospholipids as well as biodegradable polymers.
    Proc SPIE 01/2008;
  • Source
    Luis A. Quintero, Shawn Hunt, Max Diem
    [Show abstract] [Hide abstract]
    ABSTRACT: Raman spectroscopy measurements are affected by various types of spurious signals or noise. These spurious signals in the detection system are mainly produced by cosmic rays, read-out noise and thermal noise. Because of the very different nature of the various noise signals, the procedure to estimate a desired materials spectral response from the measured signal is generally divided into two sequential stages. The first stage removes the impulsive noise caused by cosmic rays, and the second attempts to remove the rest of the noise. In this work, the algorithm for removing the impulsive noise is based on a system which uses both a median filter and classic pattern recognition techniques. The algorithm not only removes the impulse, but replaces the missing values with the best estimates including system noise. In addition, spectrum denoising to minimize the loss of information is studied. The implemented algorithms are tested with synthetic and real spectrums, real spectrums are from Raman Imaging of biological materials which were provided by the research group led by professor Max Diem at Northeastern University. The algorithms are useful for all software tools that analyze Raman spectroscopy data.
    Research Thrust R2 Presentations.

Publication Stats

32 Citations
16.60 Total Impact Points

Top Journals

Institutions

  • 2011
    • University of Puerto Rico at Cayey
      Cayey, Cayey, Puerto Rico
  • 2010
    • University of Puerto Rico at Mayagüez
      Mayagüez, Mayaguez, Puerto Rico
  • 2009
    • Northeastern University
      • Department of Chemistry and Chemical Biology
      Boston, MA, United States